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9322462d14b31c38b92376dab6e672f367eb5db86b8c9d740d2fbfcb9071af73
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2026-02-02T00:00:00-05:00
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Missing links prediction: comparing machine learning with physics-rooted approaches
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arXiv:2601.23061v1 Announce Type: new Abstract: An active research line within the broader field of network science is the one concerning link prediction. Close in scope to network reconstruction, link prediction targets specific connections with the aim of uncovering the missing ones, as well as predicting those most likely to emerge in the future, from the available information. In this paper, we consider two families of methods, i.e. those rooted in statistical physics and those based upon machine learning: the members of the first family identify missing links as the most probable non-observed ones, the probability coefficients being determined by solving maximum-entropy benchmarks over the accessible network structure; the members of the second family, instead, associate the presence of single edges to explanatory node-specific variables. Running likelihood-based models such as the Configuration Model, or one of its many fitness-based variants, in parallel with the Gradient Boosting Decision Tree algorithm reveals that the former's accuracy is comparable to (and sometimes slightly higher than) the latter's. Such a result confirms that white-box algorithms are viable competitors to the currently available black-box ones, being computationally faster and more interpretable than the latter.
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https://arxiv.org/abs/2601.23061
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Academic Papers
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7dcab8c58972586d2cb19c8e4d86408dbc1c083e05899a3a0852d31f664923f9
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2026-02-02T00:00:00-05:00
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Magnetic Skyrmion Encoding by Structured Light
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arXiv:2601.23067v1 Announce Type: new Abstract: Structured light fields, featuring unique topological properties and high tunability, have opened new frontiers in light-matter interactions with magnetic systems. However, the ultrafast and reconfigurable optical encoding of various types of topological magnetic textures remains a significant challenge. Here, we systematically investigate the encoding mechanism of structured light in magnets via the higher-order Poincar\'e sphere. By uncovering the precise relationship between the winding number of structured light and the topological charge of magnetic textures, we establish a fundamental topological connection between light and magnetism. This framework enables ultrafast, all-optical encoding of diverse topological spin textures in magnetic media, including skyrmions, antiskyrmions and skyrmion bags. Our work advances the fundamental understanding and all-optical control of topological magnetism, offering a promising route for designing skyrmion-based devices.
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https://arxiv.org/abs/2601.23067
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Academic Papers
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82c42ca334ffffe8ddaee0d9e29d658c78d5c298e6f04414db47f1a42b12b877
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2026-02-02T00:00:00-05:00
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ThermoLIB -- A Python Library for Constructing and Post-Processing Free Energy Surfaces to Extract Thermodynamic and Kinetic Properties
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arXiv:2601.23071v1 Announce Type: new Abstract: ThermoLIB is Python/Cython library designed to be used as a post-processing tool for constructing free energy surfaces from the output of molecular simulations, transforming them between different collective variables (CVs) and extracting thermodynamic and kinetic information. ThermoLIB is available for download on GitHUB and comes with extended documentation as well as many tutorials. The implementation is based on the theory of maximum likelihood estimators and includes error bars on and full covariance matrix between all points on the free energy surface using the Fisher information matrix. The free energy surfaces can be transformed a posteriori to other collective variables, projected towards lower dimensional CV-spaces and even deprojected towards higher dimensional CV-spaces if additional information from the simulation is provided in the form of a conditional probability. Finally, one can extract usefull thermodynamic and kinetic properties such as the reaction free energy and kinetic rate constant. Error bars on the free energy surfaces are propagated throughout al these operations. We briefly illustrate the capabilities of ThermoLIB by means of some tutorials and case studies.
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https://arxiv.org/abs/2601.23071
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Academic Papers
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44e0012483f5e0eb74e84aa1129e89f06fd33db7c95cdde8676e09f4ad71a1c1
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2026-02-02T00:00:00-05:00
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A Universal Convolution-Based Pre-processor to Correct the Prevalence-Incidence Gap in SIR, SEIR, and SIRS Modeling
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arXiv:2601.23077v1 Announce Type: new Abstract: Traditional compartmental models, including SIR, SEIR, and SIRS frameworks, remain the analytical standard for epidemic forecasting. However, real-world data validation consistently reveals significant predictive failures, such as peak underestimations of up to 50%. This research identifies a persistent fundamental methodological error: the calibration of prevalence-based (stock) models using raw daily incidence (flow) data without proper transformation. We propose an integrated protocol utilizing an exponentially weighted convolution to reconstruct active cases from reported incidence: $I(t) \approx \frac{1}{p} \int_{0}^{t} NDC(\tau) e^{-\gamma(t-\tau)} d\tau$. This transformation accounts for the recovery rate $\gamma$ and the ascertainment rate $p$. We demonstrate that increasing structural complexity, such as adding latency (SEIR) or waning immunity (SIRS), fails to resolve the incidence-prevalence gap. Simulation results show that without the proposed universal pre-processor, these advanced models inherit the systematic biases of misaligned data types, leading to significant errors in estimating latent periods and the "heavy tail" of endemicity. The proposed convolution transformation must serve as a universal prerequisite for any compartmental framework, bridging the gap between clinical reporting and mechanistic modeling.
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https://arxiv.org/abs/2601.23077
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Academic Papers
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5bfadf09d1dd1e64a5a97dc79e5f92dd4766a800950f0ec9bdf91966a74a3e6b
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2026-02-02T00:00:00-05:00
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Stability prediction of vortex induced vibrations of multiple freely oscillating bodies
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arXiv:2601.23097v1 Announce Type: new Abstract: The vortex-induced vibration of multiple spring-mounted bodies free to move in the orthogonal direction of the flow is investigated. In a first step, we derive a Linear Arbitrary Lagrangian Eulerian (L-ALE) method to solve the fluid-structure linear problem as well as a forced problem where a harmonic motion of the bodies is imposed. We then propose a low computational-cost impedance-based criterion to predict the instability thresholds. A global stability analysis of the fluid-structure system is then performed for a tandem of cylinders and the instability thresholds obtained are found to be in perfect agreement with the predictions of the impedance-based criterion. An extensive parametric study is then performed for a tandem of cylinders and the effects of mass, damping and spacing between the bodies are investigated. Finally we also apply the impedance-based method to a three-body system to show its validity to a higher number of bodies.
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https://arxiv.org/abs/2601.23097
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Academic Papers
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02d5aa13a4c6ecab0913ff21c8a0d16a9738bf65a1080042409da16735169ce0
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2026-02-02T00:00:00-05:00
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High-bandwidth frequency domain multiplexed readout of transition-edge sensors for neutrinoless double beta decay searches
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arXiv:2601.23106v1 Announce Type: new Abstract: The next-generation of cryogenic neutrinoless double-beta decay experiments require increasingly fast readout in order to improve background discrimination. These experiments, operated as cryogenic calorimeters at $\sim$10 mK, are usually read out by high-impedance neutron transmutation doped (NTD) thermistors, which provide good energy resolution, but are limited by $\sim$1 ms response times. Superconducting detectors, such as transition-edge sensors (TESs) with a time resolution of $\sim$100 $\mu$s, offer superior timing performance over NTD semiconductor bolometers. To make this technology viable for an application to a thousand or more channels, multiplexed readout is necessary in order to minimize the thermal load and radioactive contamination induced by the readout. Frequency-domain multiplexing readout (fMux) for TESs, previously developed at Berkeley Lab and McGill University, is currently in use for mm-wave telescopes with detector sampling rates in the order of 100 Hz. We demonstrate a new readout system, based on the McGill/Berkeley digital fMux readout, to satisfy the higher bandwidth and noise requirements of the next generation of TES-instrumented cryogenic calorimeters. The new readout samples detectors at 156 kHz, three orders of magnitude faster than its cosmology-oriented predecessor. Each multiplexing readout module comprises ten superconducting resonators in the MHz range and a superconducting quantum interference device (SQUID), interfaced to high-bandwidth field programmable gate array (FPGA)-based electronics for digital signal processing and low-latency feedback.
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https://arxiv.org/abs/2601.23106
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Academic Papers
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76763c6ccd530236685b01c0946366f31b2d546d42e0c485ab3c1432848cc2f6
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2026-02-02T00:00:00-05:00
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A centimeter-sized gas pressure sensor for high-vacuum measurements at cryogenic temperatures
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arXiv:2601.23117v1 Announce Type: new Abstract: Gas pressure sensors based on nanomechanical membranes have recently demonstrated an ultra-wide ten-decade measurement range, a gas-type-independent response, and a self-calibrating operation with uncertainties of approximately $1\,\%$. The readout relied on tabletop free-space laser interferometers. Here we present a centimeter-sized, portable implementation in which a square Si$_3$N$_4$ membrane is read out via a fiber-based laser interferometer. We perform pressure measurements between $5\times10^{-5}$ and $10^{-1}$~mbar in a confined $0.7$~L volume cooled to $78$~K. Because no suitable commercial pressure sensor exists for direct cryogenic comparison, we benchmark our device against room-temperature commercial gauges connected to the cold volume through a pipe of limited conductance. The measured relationship between the two sensors is compared with models accounting for temperature- and pumping-induced pressure gradients within the measurement chamber. These models agree with the measurements to within $<10\,\%$ for helium and $<13\,\%$ for nitrogen. The achieved readout sensitivity of $S_x = 8\times10^{-14}\,\mathrm{m}/\sqrt{\mathrm{Hz}}$ theoretically enables resolving the thermal displacement noise spectrum of a trampoline membrane at atmospheric pressure, with a peak response of $48\,S_x$ $\left(25\,S_x\right)$ at $295\,\mathrm{K}$ $\left(78\,\mathrm{K}\right)$. Our results suggest that the previously achieved pressure measurement range of ten decades with trampoline membranes is compatible with fiber-based optical readout. This paves the way for widely applicable pressure sensors in the centimeter size range in cryogenic environments.
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https://arxiv.org/abs/2601.23117
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Academic Papers
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b0d46a3a4dd98efb8ca1030ddfe8806b9f2674ca2586481c200336b1052535b6
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2026-02-02T00:00:00-05:00
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Spontaneous four-wave mixing in a thin layer with second-order nonlinearity
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arXiv:2601.23137v1 Announce Type: new Abstract: Pairs of entangled photons are crucial for photonic quantum technologies. The demand for integrability and multi-functionality suggests 'flat' platforms - ultrathin layers and metasurfaces - as sources of photon pairs. With the success in demonstrating spontaneous parametric down-conversion (SPDC) from such sources, an alternative process to generate photon pairs, spontaneous four-wave mixing (SFWM), also starts to attract interest. In materials with nonzero second-order nonlinear susceptibility $\chi^{(2)}$, SFWM can generate photon pairs both directly, through the third-order nonlinear susceptibility $\chi^{(3)}$, and in a cascaded way, through second harmonic generation (SHG) followed by SPDC. Usually, the cascaded process is more efficient. Here, we show that in a thin layer, direct SFWM dominates, because the wavevector mismatch for SFWM is much smaller than for SHG or SPDC. To demonstrate it, we implement the photon pair generation via SFWM in a second-order nonlinear material - a thin layer of lithium niobate (LN). The existence of both second- and third-order nonlinear processes offers broader opportunities for quantum state engineering.
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https://arxiv.org/abs/2601.23137
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Academic Papers
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2655427cd84017bf3e4841bcea0ed9fa0dcae97057ac964879f80f45002ad02d
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2026-02-02T00:00:00-05:00
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A predictive formula for the H-mode electron separatrix density: Bridging regression and physics-based models across C-Mod, AUG and JET tokamaks
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arXiv:2601.23140v1 Announce Type: new Abstract: The electron density at the separatrix ($n_{e,\mathrm{sep}}$) plays a central role in balancing energy confinement, detachment achievement, and ELM suppression in tokamaks, thereby influencing core-edge integration. To study what determines this key parameter, a database of H-mode separatrix density measurements from Alcator C-Mod, ASDEX Upgrade, and JET tokamaks has been assembled using a consistent analysis method across all devices. This dataset is used to derive a regression scaling expression based solely on engineering parameters, and the results are compared to predictions from the two-point model. The agreement found is remarkable: both the regression and model provide similar parameter dependencies and tokamak-specific multiplicative constants. Building on this agreement, a fully predictive formula that combines the regression dependencies and the two-point model multiplicative constant is proposed. This formula is able to estimate $n_{e,\mathrm{sep}}$ across the three machines within a factor of 1.5, and provides projections to next-step devices (ITER, SPARC, DTT, JT-60SA and COMPASS-U) that are in agreement with available SOLPS simulations.
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https://arxiv.org/abs/2601.23140
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Academic Papers
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06452f6f074914fcc3cf981e16fbaada00bab9dc6ad91a6812ac5d0b6affc613
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2026-02-02T00:00:00-05:00
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Forward and Inverse Mantle Convection with Neural Operators
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arXiv:2601.23178v1 Announce Type: new Abstract: Thermal state reconstruction -- reversing convection to recover the thermal structure of the mantle at an earlier geologic time -- is an important tool to understand the evolution of mantle convection and its relation to seismic tomographic images and observations at the surface. Thermal state reconstructions are computationally expensive. Here we transformed the basic computational element, numerical solvers, into neural operators, a class of machine learning models for learning mappings between function spaces. Focusing on a specific architecture, Fourier Neural Operators, we demonstrate that they can represent not only a surrogate model like the Stokes system of equations using a purely physics informed approach, but also discover operators without explicit mathematical formulations or even ill-posedness from data, including the direct mapping between two convecting thermal states separated by a long time interval much larger than the Courant Fredrich Lewy condition and its reversal. These neural operators significantly accelerate forward and inverse convection modeling by transforming forward physical processes into surrogate models with lower complexity while utilizing auto-differentiation to calculate gradients. With this framework, we demonstrate the strength and weaknesses of four methods for thermal state reconstructions: Reverse buoyancy, reverse convection operator, an inversion with only the terminal thermal state, and a joint inversion with the terminal thermal state and surface velocity evolution. The reverse convection operator is shown to perform poorly in the presence of observational noise, but the joint inversion overcomes this limitation. The joint technique could probably become a solution to large-scale thermal state inversion problems using seismic tomography and plate tectonic reconstructions.
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https://arxiv.org/abs/2601.23178
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Academic Papers
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eab54bdb9b62144b3c619dd40a08aa40b75f51551465ca6f7d3954d219ed9069
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2026-02-02T00:00:00-05:00
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Hybrid physics-data-driven modeling for sea ice thermodynamics and transfer learning
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arXiv:2601.23190v1 Announce Type: new Abstract: This study explores a physics-data driven hybrid approach for sea-ice column physics models, in which a machine learning (ML) component acts as a state-dependent parameterization of forecast errors. We examine how perturbations in snow thermodynamics and sea-ice radiative properties affect forecast errors, and train dedicated neural networks (NNs) for each model configuration. The performance of the hybrid models is evaluated for long lead-time forecasts and compared against a benchmark system based on climatological forecast-error estimates. The NN-based hybrids prove to be stable, robust to initial condition and atmospheric forcing errors, and consistently outperform their climatology-based counterpart. To derive guiding principles for efficiently handling possible physical model updates, we perform transfer learning experiments to test whether pretrained NNs optimized for one model configuration can be successfully adapted to another. Results indicate that direct evaluation of pretrained networks on the target task provides useful insights into their adaptability, recommending transfer learning whenever performance exceeds a trivial baseline. Finally, a feature-importance analysis shows that atmospheric forcing inputs have negligible influence on NN predictive skill, while ice-layer enthalpies play a key role in achieving satisfactory performance.
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https://arxiv.org/abs/2601.23190
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Academic Papers
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5904171eb0a14d360331b4e41fe9c79355c2ed5203fd99af993ddeb7f0bc7e5a
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2026-02-02T00:00:00-05:00
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High-Efficiency Hexagonal Nanowire MAPbI3 Perovskite Solar Cell with Broadband Light Trapping
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arXiv:2601.23191v1 Announce Type: new Abstract: Perovskite solar cells (PSCs) have emerged as strong contenders for the next generation of photovoltaic (PV) technologies due to their exceptional light absorption properties, tunability, and affordability in manufacturing. Here, we presented an ingenious hexagonal nanowire (HNW)-based PSC that achieves broadband absorption, minimizes reflectance, and offers robust polarization insensitivity by improving light-matter interaction and increasing charge-collection efficiency. The rotational symmetry of the HNW configuration yielded polarization-independent absorbance under both TE and TM illumination across the visible and near-infrared spectra. The optimization of the geometrical parameters of CH3NH3PbI3-based HNW structure, including diameter, period, and fill ratio, offered a wide rangeof variations that influenced both optical properties and device performance. To further intensify photon confinement, a dielectric SiO2 sphere is partially embedded in the ITO layer, improving long-wavelength absorbance and increasing electron-hole pair generation near the active region. We analyzed the finite-difference time-domain (FDTD) method to examine the optical properties of our proposed structure. This study demonstrates that our proposed structure has achieved a higher generation rate, enhanced absorbance, and a higher optical short-circuit current density (Jsc) of 29.53 mA/cm2. Electrical performance is assessed by solving the coupled drift-diffusion and Poisson equations for the dynamics of carrier transport. The optimized HNW structure achieved a notable power conversion efficiency of 24.2%, highlighting a strong connection between optical confinement and effective carrier transport. These attributes render the proposed HNW PSC a viable option for high-performance PV systems and scalable thin-film solar technologies.
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https://arxiv.org/abs/2601.23191
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Academic Papers
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6ebec671f7778967c2749e1f4ce1cec073ea4723589d5005035c19a17b9106c4
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2026-02-02T00:00:00-05:00
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Characterizing the Backscattered Spectrum of Mie Spheres
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arXiv:2601.23194v1 Announce Type: new Abstract: This study describes both experimentally and theoretically an important hitherto undiscovered feature of the scattering of micron_sized spherical objects when illuminated with highly focused circularly polarized light. This is a regime of high experimental relevance which has not been described in full detail. The experiments are complemented with the analytical formulas explaining the field scattered directed toward the backward hemispace. In particular, it is proven that this field shows a very regular oscillatory dependency with the optical size. This phenomenon is typically hidden in the total scattered field, as the field is scattered much less toward the backward hemisphere than toward the forward one. These regular oscillations are measured experimentally. It is proven that, by analyzing them, it is possible to determine the index of refraction of isolated micron_sized particles, opening new paths for applications in sensing and metrology.
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https://arxiv.org/abs/2601.23194
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Academic Papers
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bfd047a4b6288857331baa1644220f7267d046d322e7bbe4e35bd2639eeb888d
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2026-02-02T00:00:00-05:00
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Detection of Hybrid Optical Anapoles in Dielectric Microspheres
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arXiv:2601.23202v1 Announce Type: new Abstract: Nonradiating optical anapoles are special configurations of charge_current distributions that do not radiate. It was theoretically predicted that, for microspheres, electric and magnetic dipolar coefficients can simultaneously vanish by engineering the incident light, leading to the excitation of nonradiating hybrid optical anapoles. In this work, the experimental detection of hybrid optical anapoles in dielectric microspheres (TiO2) is reported using dual detection optical spectroscopy, developed to enable sequential measurement of forward and backward scattering under tightly_focused Gaussian beam (TFGB) illumination. The results show that the excitation of TiO2 microspheres (diameter, d approx. 1 um) under TFGB illumination leads to the appearance of scattering minima in both the forward and backward directions within specific wavelength ranges. These scattering minima are found to be due to vanishing electric and magnetic dipolar coefficients associated with hybrid optical anapoles. The ability to confine electromagnetic fields associated with hybrid optical anapoles can give rise to several novel optical phenomena and applications.
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https://arxiv.org/abs/2601.23202
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Academic Papers
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3ca653ed922e1c501125c93c515adec402f897e55494bc8c8c172c8494674fa9
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2026-02-02T00:00:00-05:00
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Optical forces, helicity, angular momentum and how they are all intertwined
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arXiv:2601.23214v1 Announce Type: new Abstract: The theoretical description of optical forces and torques on micron_sized particles is a crucial area of research and has formed the foundation for advancements in optical trapping and manipulation technologies. In this study, we derive analytical expressions for optical forces and torques on micron_sized spherical particles illuminated by focused Laguerre_Gaussian (LG) beams, employing the well_defined helicity multipolar decomposition of electromagnetic fields and Mie theory. We developed a multifunctional program, Multipolar Optical Forces Toolbox, based on this theoretical framework. The program, available on GitHub, was used to generate optical trapping stability maps. These maps predict trap stability across a wide range of system parameters and serve as a practical tool for designing advanced optical trapping experiments. Our analysis reveals the important role of helicity p and orbital angular momentum l on the dynamics of particles trapped off_axis in LG beams and demonstrates the unique nature of the tangential torque. Our findings also highlight notable differences in longitudinal optical forces resulting from pure helicity modifications in Gaussian beams. Furthermore, we showcase the ability of LG beams to isolate Mie resonances, offering a novel approach to locate the spectral positions of the resonances of high multipolar modes. These insights deepen the understanding of helicity in LG optical traps and pave the way for the development of more advanced optical manipulation techniques.
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https://arxiv.org/abs/2601.23214
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Academic Papers
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f03aac5a1724002bf973f53720fa9f3ef2151cfbfb7faac3dac28c325bf4819b
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2026-02-02T00:00:00-05:00
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Leveraging configuration interaction singles for qualitative descriptions of ground and excited states: state-averaging, linear-response, and spin-projection
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arXiv:2601.23270v1 Announce Type: new Abstract: While configuration interaction singles (CIS) provides a computationally efficient description of excited states, it systematically overestimates excitation energies and performs poorly for strongly correlated systems, partially due to the lack of orbital relaxation and the strong ground-state bias of Hartree-Fock orbitals. To address these limitations, we present a unified variational framework that extends CIS by incorporating orbital optimization (state-specific and state-averaged), linear-response orbital relaxation via double-CIS schemes, and spin-symmetry breaking and restoration. In spin-projected state-averaged formulations, standard multistate parametrizations are no longer valid because the projection operator breaks the unitary invariance of orbital rotations and induces nonorthogonal couplings among states. By formulating a rigorous state-averaged objective in the projected subspace, we derive analytic gradients and Hessians and enable robust optimization using a trust-region augmented Hessian algorithm. Benchmark calculations show that spin projection alone significantly exacerbates the CIS overestimation in weakly correlated systems, whereas combining spin projection with state averaging or double-CI corrections substantially reduces errors, particularly for Rydberg excitations. We further demonstrate that state averaging and spin projection provide complementary and essential benefits in strongly correlated regimes, as illustrated by the bond dissociation of hydrogen fluoride.
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https://arxiv.org/abs/2601.23270
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Academic Papers
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d684dbd81b4adaa015af97f9fa839ac35c8c618479fe15cc42165b0f7803f4b7
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2026-02-02T00:00:00-05:00
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Time-Resolved Interferometric Measurements of Plasma Density Evolution in Laser-Driven Capacitor-Coil Targets
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arXiv:2601.23271v1 Announce Type: new Abstract: Laser-driven capacitor-coil targets provide a compact platform for generating strong magnetic fields and are widely used in magnetized high-energy-density plasma experiments. In addition to magnetic-field generation, these targets also produce plasma in the coil region, which can influence the subject physical processes, interact with secondary targets or external plasmas in their applications. However, direct, time-resolved measurements of the plasma density surrounding the coil remain limited. Here, we report interferometric measurements of the plasma density evolution in laser-driven capacitor-coil targets irradiated by the University of Osaka LFEX laser. Two-dimensional electron density maps reveal two distinct plasma sources loading the coil region: plasma generated in the coil itself and plasma produced by laser ablation of the target plates. These results provide quantitative information on plasma loading and evolution in capacitor-coil targets and are directly relevant to the design and modeling of magnetized high-energy-density plasma experiments.
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https://arxiv.org/abs/2601.23271
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Academic Papers
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6861d123633e57c836e8b87bf168536700f15f6bbada67c9064f5ff541ad2099
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2026-02-02T00:00:00-05:00
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The two-positron gluonic bond as a manifestation of "super" van der Waals interactions
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arXiv:2601.23275v1 Announce Type: new Abstract: Recently, it has been demonstrated theoretically that the interaction of two PsH atoms, each being a stable bound state of a hydrogen atom and a positronium atom, is attractive, leading to the formation of a molecular complex denoted as (PsH)2. However, the physical nature of this interaction has remained elusive. In the present study, we show that the stabilizing mechanism is entirely encoded in the quantum correlations between the two positrons and, to a lesser extent, in the electron-positron correlations. Notably, the interaction cannot be recovered at the mean-field (Hartree-Fock) level, nor by computational models that include only electron-electron correlation effects. Accordingly, the bond formed between PsH units, termed here a two-positron gluonic bond to emphasize its fundamentally distinct character from the two-positron covalent bonds present in pure antimatter molecules, emerges only when matter and antimatter particles form a common bound state. When classified within the framework of known bonding mechanisms, this gluonic bond falls into the category of stabilizing dispersion interactions, giving rise to a van der Waals complex. However, its remarkably large bond dissociation energy, compared with those of strongly bonded van der Waals complexes of similar size, reveals an anomalously strong interaction. For this reason, we propose that (PsH)2 is most appropriately described as a "super" van der Waals complex stabilized by a "super" van der Waals bond.
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https://arxiv.org/abs/2601.23275
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Academic Papers
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611377046edad0562dc2713fb756ae44a3682a49ff1e2b22162a700d57ee449c
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2026-02-02T00:00:00-05:00
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The Initial Mass Function as the Equilibrium State of a Variational Process: why the IMF cannot be sampled stochastically
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arXiv:2601.20998v1 Announce Type: cross Abstract: The stellar initial mass function (sIMF) is often treated as a stochastic probability distribution, yet such an interpretation implies Poisson noise that is inconsistent with growing observational evidence. In particular, the observed relation between the mass of the most massive star formed in an embedded cluster and the cluster's total stellar mass supports a deterministic sampling process, known as optimal sampling. However, the physical origin of optimal sampling has not been formally established in the literature. In this work, we show that the stellar mass distribution implied by optimal sampling emerges from applying the Maximum Entropy principle to the fragmentation of star-forming clumps, whose structure is set by density-dependent cooling in the optically thin regime. Here, the maximum entropy leads to unbiased distributions. By applying calculus of variations to minimize the entropy functional obtained assuming fragmentation, we recover the power-law form of the sIMF, and we show that any distribution deviating from the sIMF violates the Maximum Entropy principle. This work provides a first-principles foundation for the deterministic nature of star formation. Thus, the sIMF is the distribution resulting from a maximally unbiased system.
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https://arxiv.org/abs/2601.20998
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5f5406d638d8ea6e6af6f088166ad1d0c4c4800c56eede552a7618d0261a1b0a
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2026-02-02T00:00:00-05:00
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Learning to Advect: A Neural Semi-Lagrangian Architecture for Weather Forecasting
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arXiv:2601.21151v1 Announce Type: cross Abstract: Recent machine-learning approaches to weather forecasting often employ a monolithic architecture, where distinct physical mechanisms (advection, transport), diffusion-like mixing, thermodynamic processes, and forcing are represented implicitly within a single large network. This representation is particularly problematic for advection, where long-range transport must be treated with expensive global interaction mechanisms or through deep, stacked convolutional layers. To mitigate this, we present PARADIS, a physics-inspired global weather prediction model that imposes inductive biases on network behavior through a functional decomposition into advection, diffusion, and reaction blocks acting on latent variables. We implement advection through a Neural Semi-Lagrangian operator that performs trajectory-based transport via differentiable interpolation on the sphere, enabling end-to-end learning of both the latent modes to be transported and their characteristic trajectories. Diffusion-like processes are modeled through depthwise-separable spatial mixing, while local source terms and vertical interactions are modeled via pointwise channel interactions, enabling operator-level physical structure. PARADIS provides state-of-the-art forecast skill at a fraction of the training cost. On ERA5-based benchmarks, the 1 degree PARADIS model, with a total training cost of less than a GPU month, meets or exceeds the performance of 0.25 degree traditional and machine-learning baselines, including the ECMWF HRES forecast and DeepMind's GraphCast.
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https://arxiv.org/abs/2601.21151
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Academic Papers
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10e26b190aca9bd0bae0ad6b5bee8878eca7cc6d9707a0f8e356914d6b7203a5
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2026-02-02T00:00:00-05:00
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Physically-motivated priors in the local distance ladder significantly reduce the Hubble tension
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arXiv:2601.22215v1 Announce Type: cross Abstract: Determinations of the Hubble constant based on the local distance ladder remain in significant tension with early-Universe inferences from the cosmic microwave background. While this tension is often discussed in terms of new physics or unmodeled systematics, the role of the assumed priors on the model parameters has received comparatively little attention. Recently, Desmond et al. (2025) pointed out that the commonly adopted flat prior on distance moduli upweights smaller distances and systematically favors high inferred values of the Hubble constant. Motivated by this observation, we perform a comprehensive Bayesian recalibration of the distance ladder, applying physically motivated priors uniformly to all distances, including the Milky Way Cepheids, which are incorporated directly into the joint fit. Together with a conservative treatment of the Gaia EDR3 residual parallax offset, the Hubble constant shifts from $H_0 = 73.0 \pm 1.0 \, \mathrm{km/s/Mpc}$ to $H_0 = 70.6 \pm 1.0 \, \mathrm{km/s/Mpc}$, reducing the Hubble tension from $5 \, \sigma$ to $2 \, \sigma$. Our results show that the assumed priors -- often treated as innocuous defaults -- may play a central role in the Hubble tension. Because all local distance ladders rely on the calibration of distances, similar prior-driven effects are expected to arise across distance-ladder methods.
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https://arxiv.org/abs/2601.22215
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66dd0271a5c9e6414b59939ad36b84ee47ddf20cd2005c7dbcd0a41eaef7a94b
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2026-02-02T00:00:00-05:00
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Three-dimensional squeezing of optically levitated nanospheres
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arXiv:2601.22283v1 Announce Type: cross Abstract: We propose a protocol to measure impulses beyond the standard quantum limit. The protocol reduces noise in all three spatial dimensions and consists of squeezing a mechanical system's state via a series of jumps in the frequency of the harmonic potential. We quantify how decoherence in a realistic system of an optically levitated, dielectric nanoparticle limits the ultimate sensitivity. We predict that $\sim$10 dB of squeezing is achievable with current technology, enabling quantum-enhanced detection of weak impulses.
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https://arxiv.org/abs/2601.22283
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b6f0c9c9a7ce2709d5ed4eb0c9388a6fb4566574aeb6ea5457c7d6599c208547
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2026-02-02T00:00:00-05:00
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A Generalized Analytical Heat Transfer Model for Enhanced Geothermal Systems: Capturing Fracture Interactions and Correcting Classical Optimistic Predictions
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arXiv:2601.22316v1 Announce Type: cross Abstract: Numerical analytical heat transfer models play a critical role in geothermal design and feasibility studies. Classical solutions, such as those proposed by Gringarten et al. 1975, rely on simplified assumptions and systematically overestimate thermal performance, which can lead to unrealistic engineering decisions. This study presents a generalized analytical model for enhanced geothermal systems that explicitly captures thermal interactions between fractures while preserving analytical tractability. The formulation is based on Green\'s functions and reproduces realistic thermal behavior under conditions representative of fractured geothermal reservoirs. The resulting solution is computationally efficient and sufficiently simple to be implemented directly in standard spreadsheets, without requiring Laplace space transformations or numerical inversion algorithms. The model is validated against numerical simulations performed using CMG STARS and Volsung software, showing close agreement in temperature evolution, including the effects of interacting fractures. Compared with classical analytical approaches, the proposed model corrects optimistic bias and provides more reliable predictions of production temperature and energy recovery. These results have direct implications for geothermal feasibility studies, well design, and power forecasting, effectively bridging the gap between legacy analytical models and numerical or commercial engineering tools. Building on the analytical framework originally introduced by Gringarten et al. 1975, the proposed formulation generalizes classical heat transfer solutions to account for fracture interaction while retaining analytical simplicity and practical applicability.
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https://arxiv.org/abs/2601.22316
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acffc1fc2e3926d760fbfb5a605181af789b4619a926ffdb70e05bd509e54330
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2026-02-02T00:00:00-05:00
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Conversion Layer Controls the Evolution of Magnetic Deflections Near the Alfven Surface
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arXiv:2601.22321v1 Announce Type: cross Abstract: We examine the statistics of Alfvenic deflections in both sub-Alfvenic and super-Alfvenic solar wind with particular focus on a common parameter that underlies the definition of switchbacks: the magnetic deflection angle. Our findings are in general agreement with earlier studies that suggest magnetic deflection angles > 90 degrees are very unlikely to occur in sub-Alfvenic regimes. We find that their upper limit exhibits an identifiable trend with the Alfven Mach number Ma, suggesting that gradual steepening of Alfvenic deflections with increasing Ma is a plausible mechanism controlling deflection angles in the young solar wind. Further analysis reveals that large velocity fluctuations tend to be important in the largest sub-Alfvenic magnetic deflections with increasing contributions from the parallel component very close to Ma = 1, while virtually no magnetic deflections in the super-Alfvenic regime exhibit such large velocity perturbations. We also determine the local ratio of radial Poynting flux SR to kinetic energy flux KR and find that large sub-Alfvenic deflection angles tend to be dominated by SR, while super-Alfvenic deflections are eventually dominated by the KR associated with the radial solar wind flow. Our results show that within the vicinity of the Alfven surface (where Ma = 1), there is a critical region of parameter space within which velocity deflections approach the Alfven velocity and KR/SR is close to unity. We refer to this region (where | log10(Ma)| < 0.2) as the conversion layer. The conversion layer may play a significant role in the evolution of magnetic defections by providing the medium for converting magnetic energy to particle energy and likely driving the formation of magnetic switchbacks in super-Alfvenic solar wind.
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https://arxiv.org/abs/2601.22321
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d2f73cfa3e5dec31c8dd8d1b9579fbf0786163379d53ab477559dfca44d62fd0
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2026-02-02T00:00:00-05:00
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Revisiting the energy-momentum squared gravity
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arXiv:2601.22333v1 Announce Type: cross Abstract: In this paper we have revisited the energy-momentum squared gravity theory, by taking into account the second derivative of the matter Lagrangian with respect to the metric, encapsulating relations originated from thermodynamical grounds. After obtaining the scalar tensor representation of the energy-momentum squared gravity with the new corrections, we have analyzed the physical implications by relying on the linear stability theory. The results show that the current cosmological system is compatible with the expansion of the Universe for some specific matter Lagrangians, explaining the emergence of matter domination era, approaching the late time accelerated expansion era close to the de-Sitter phenomenology.
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https://arxiv.org/abs/2601.22333
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ebefd657782dcf896bdc5e1f5a35fd48cce632a99de1dff5a40994612501ae0a
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2026-02-02T00:00:00-05:00
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Enhanced Yield Rate of \textsuperscript{229m}Th via Cascade Decay in Storage Rings and Electron Beam Ion Traps
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arXiv:2601.22417v1 Announce Type: cross Abstract: The low-energy nuclear isomeric state of \textsuperscript{229m}Th provides a unique bridge between nuclear and atomic physics, enabling applications such as nuclear clocks and precision metrology. However, efficient and controllable production of \textsuperscript{229m}Th remains a major experimental challenge. We propose an efficient scheme to produce the $^{229\mathrm{m}}$Th in storage rings (SRs) and electron beam ion traps (EBITs), using a cascade decay pathway. Highly charged ions are excited to higher nuclear states via nuclear excitation by inelastic electron scattering (NEIES) and nuclear excitation by electron capture (NEEC), followed by radiative or internal conversion cascades that populate the isomer. Our calculations demonstrate that, under typical SRs and EBITs conditions, optimized indirect excitation pathways significantly enhance \textsuperscript{229m}Th production rate. In particular, NEIES can provide an enhancement of up to four orders of magnitude through cascade de-excitation at high energies, while NEEC can contribute an additional enhancement of up to several tens of times. Such a significant increase in the \textsuperscript{229m}Th yield rate would facilitate its application in various nuclear photonics fields, especially in the development of atomic nuclear clocks.
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https://arxiv.org/abs/2601.22417
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f83bec410a2635661b88807a95dc989757ebedcc864ced71212870c6bdd84866
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2026-02-02T00:00:00-05:00
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Synthesis of Monolayer Ice on a Hydrophobic Metal Surface
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arXiv:2601.22460v1 Announce Type: cross Abstract: Understanding water-metal interactions is central to disciplines spanning catalysis, electrochemistry, and atmospheric science. Monolayer ice phases are well established on hydrophilic surfaces, where strong water-substrate interactions stabilize ordered hydrogen-bond networks. In contrast, their formation on hydrophobic metals has been deemed ther-modynamically unfavourable, with water typically assembling into amorphous films, three-dimensional crystallites, or interlocked bilayer ice. Here, we demonstrate the synthesis of a monolayer ice phase on the hydrophobic Au(111) surface using a low-energy-electron-assisted growth method. Combined experimental characterizations including low-energy electron diffraction, angle-resolved photoemission spectroscopy, and X-ray photoelectron spectroscopy, complemented by first-principles calculations, prove that the monolayer ice phase composes of intact water molecules. This approach provides a generalizable strategy for stabilizing ordered two-dimensional ice on inert substrates and offers new insight into the interplay between water and low-energy electrons at hydrophobic interfaces.
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https://arxiv.org/abs/2601.22460
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63df748e259bdb8c3d619075246ee87254750f2c20af88837af23ac765f83b1a
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2026-02-02T00:00:00-05:00
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Understanding the sign problem from an exact Path Integral Monte Carlo model of interacting harmonic fermions
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arXiv:2601.22559v1 Announce Type: cross Abstract: This work shows that the recently discovered operator contraction identity for solving the discreet Path Integral of the harmonic oscillator can be applied equally to fermions in any dimension. This then yields an exactly solvable model for studying the sign problem where the Path Integral Monte Carlo energy at any time step for any number of fermions is known analytically, or can be computed numerically. It is found that repulsive/attractive pairwise interaction shifts the sign problem to larger/smaller imaginary time, but does not make it more severe than the non-interacting case. More surprisingly, for closed-shell number of fermions, the sign problem goes away at large imaginary time. Fourth-order and newly found variable-bead algorithms are used to compute ground state energies of quantum dots with up to 110 electrons and compared to results obtained by modern neural networks.
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https://arxiv.org/abs/2601.22559
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fd61713a15c8e5cd8fa2770998473cd87e8591e0e10299ebc33366d580ca890b
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2026-02-02T00:00:00-05:00
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Unconventional Distance Scaling of Casimir-Polder Force between Atomic Arrays
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arXiv:2601.22640v1 Announce Type: cross Abstract: Conventionally, dispersion forces mediated by quantum vacuum fluctuations are known to exhibit universal distance scalings, with retardation typically leading to a faster decay of the interaction. Here, we show that this expectation fails for intrinsically discrete systems. Using the microscopic scattering approach, we study the Casimir-Polder interaction between two atomic arrays, and uncover an unconventional distance scaling in which the force crosses over from a faster decay at short separations to a slower decay in the retarded regime. This behavior originates from the discrete lattice structure and can be consistently understood within the scattering picture. Extending our analysis to Rydberg atomic arrays, we predict an even stronger deviation from conventional scaling and propose an experimentally feasible scheme for direct measurement. Our results provide a new platform for exploring dispersion forces beyond the continuum limit.
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https://arxiv.org/abs/2601.22640
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6cadaa64389f6b531e11ceb5b906b8821d3c3ac9bab50677c1351388283a4893
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2026-02-02T00:00:00-05:00
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Scattering of Squeezed Light by a Dielectric Slab
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arXiv:2601.22798v1 Announce Type: cross Abstract: We develop a quantum theory for the scattering of squeezed coherent light by a dissipative dielectric slab. Using the Green-function quantization approach, we derive the transformation of the field quadratures and show how dispersion, absorption, and multiple reflections distort the incident squeezing. We find that the slab can selectively attenuate or amplify quadrature noise depending on the slab parameters and provide expressions for the output power spectra.
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https://arxiv.org/abs/2601.22798
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05d92b53901f6dd8ba2e3a4d55506ae65276435da6289d90949411452dace5cf
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2026-02-02T00:00:00-05:00
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Ground Level Enhancement (GLE#77) in the gamma-ray component: First observation from Arctic and Antarctic stations
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arXiv:2601.22807v1 Announce Type: cross Abstract: This article presents the observations of the extreme ground-level enhancement (GLE #77) of Solar Cycle 25 that occurred on 11 November 2025, using ground-based NaI(Tl) gamma-ray detectors deployed at Arctic and Antarctic stations, together with neutron monitor data and particle measurements from the GOES-18 satellite. The event was associated with an intense X-class solar flare and a strong solar energetic proton event. This paper reports the first ground-based detection of a GLE using gamma-ray detectors operating simultaneously in both polar regions, which are concurrent with increases in neutron monitor counts. Thus highlights the capability of polar gamma-ray detectors to complement traditional neutron monitor observations during extreme solar proton events. A detailed analysis revealed distinct prompt and delayed responses during the event evolution. Interestingly, the signature of the prompt peak of GLE#77 (at 10:38 UT) was observed up to high-rigidity neutron monitors (low latitudes). However, the delayed peak (at 13:08 UT) was not seen at the stations with rigidity > 6 GV. The timing of the prompt and delayed peaks coincided with the proton flux peaks observed by the GOES-18 satellite at energies > 150 MeV and 12-99 MeV, respectively. It is observed that the GLE amplitude has a strong dependence on geomagnetic cutoff rigidity and has a weak solar zenith angle dependence.
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https://arxiv.org/abs/2601.22807
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2b5e91d433663ffb8888964aa6246b3d2397472396c0f96ae078d305118f52b8
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2026-02-02T00:00:00-05:00
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Rotational Spectroscopy as a Tool to Study Vibration-Rotation Interaction: Investigations of $^{13}$CH$_3$CN and CH$_3$$^{13}$CN up to $v_8 = 2$ and a Search for $v_8 = 2$ Transitions toward Sagittarius B2(N)
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arXiv:2601.22824v1 Announce Type: cross Abstract: Methyl cyanide, CH$_3$CN, is present in diverse regions in space, in particular in the warm parts of star-forming regions where it is a common molecule. Rotational transitions of $^{13}$CH$_3$CN and CH$_3$$^{13}$CN in their $v_8 = 1$ lowest excited vibrational states ($E_{\rm vib} \approx 520$ K) are quite prominent in Sagittarius B2(N). In order to be able to search for transitions of the next higher vibrational state $v_8 = 2$, we recorded spectra of samples enriched in $^{13}$CH$_3$CN and CH$_3$$^{13}$CN up to $v_8 = 2$ in the 35 to 1091~GHz region and reinvestigated existing spectra of CH$_3$CN in its natural isotopic composition between 1085 and 1200 GHz. Perturbations caused by near-degeneracies in $K = 4$ of $v_8 = 2^0$ and $K = 2$ of $v_8 = 2^{-2}$ yielded accurate information on the energy spacing of 22.93 and 21.79 cm$^{-1}$ between the $l$-components of $^{13}$CH$_3$CN and CH$_3$$^{13}$CN, respectively. Fermi-type interaction between $K = 13$ and 14 of $v_8 = 1^{-1}$ and $v_8 = 2^{+2}$ probe the energy differences between the two states of both isotopomers. In addition, a $\Delta K \pm2$, $\Delta l \mp1$ interaction between the ground vibrational state of $^{13}$CH$_3$CN and $v_8 = 1^{+1}$ provides information on their energy spacing. Furthermore, we obtained improved or extended ground state rotational transition frequencies of $^{13}$CH$_3$$^{13}$CN and extensive data for $^{13}$CH$_3$C$^{15}$N and CH$_3$$^{13}$C$^{15}$N. Finally, we report the results of our search for transitions of $^{13}$CH$_3$CN and CH$_3$$^{13}$CN in their $v_8 = 2$ states toward Sagittarius B2(N).
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https://arxiv.org/abs/2601.22824
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b700034960c6b6afcde913f8e9161b7c02a3377bde487fcdb00a423d41942656
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2026-02-02T00:00:00-05:00
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Millimeter and submillimeter spectroscopy of methylallene, CH$_3$CHCCH$_2$
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arXiv:2601.22872v1 Announce Type: cross Abstract: Small polycyclic aromatic hydrocarbons and somewhat larger cyano derivatives were detected in the cold dark cloud TMC-1 recently. Their formation from smaller hydrocarbons is not well understood, in part because abundances of many species are not known. Methylallene, CH$_3$CHCCH$_2$, may be one of the building blocks, but its rotational spectrum was characterized only to a very limited extent. We recorded rotational transitions in the 36$-$501 GHz region to extend the existing line list of methylallene and thus enable searches for the molecule in space. Quantum-chemical calculations were carried out to evaluate initial spectroscopic parameters. We obtained transition frequencies with $J \le 61$ and $K_a \le 21$ and resolved the internal rotation splitting of the CH$_3$ group at least partially. As a result, a full set of distortion parameters up to sixth order along with two octic ones were determined, as well as parameters describing the internal rotation of the methyl group. The spectroscopic parameters are accurate enough to identify methylallene up to 720 GHz, sufficient for searches even in the warm interstellar medium.
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https://arxiv.org/abs/2601.22872
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a55526464e27498d44e5b51d7881e37bdd910d63f897d7efc17f63eb8ec49328
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2026-02-02T00:00:00-05:00
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Leveraging Interactions for Efficient Swarm-Based Brownian Computing
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arXiv:2601.22874v1 Announce Type: cross Abstract: Drawing inspiration from swarm intelligence, we show that short-range attractive interactions between thermally driven Brownian quasiparticles enable energy-efficient optimization. As quasiparticles can be generated directly within a material, the swarm size can be adjusted with minimal energy overhead. Using an optimization task defined by a spatially varying temperature landscape, we quantitatively show that interacting swarms reliably identify global optima and significantly outperform non-interacting searchers within a well-defined regime of interaction strength and swarm size. This improvement arises from emergent cooperative behavior, where local interactions guide the swarm toward high-quality solutions without central coordination. To link our physical model to experimental realizations, we coarse-grain the quasiparticle dynamics onto a sensor lattice and generate trajectories emulating particle-tracking measurements. We further show that the interacting swarm adapts robustly to landscapes that evolve over time. These findings establish interacting Brownian quasiparticles as a physical platform for scalable and energy-efficient unconventional computing.
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https://arxiv.org/abs/2601.22874
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3d69fba01837f137c55587a1c7b4b7d1ef854a1582c97c83fbfe3a30eaf6d148
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2026-02-02T00:00:00-05:00
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How adaptation to food resources and death rates shape oscillatory dynamics in a microbial population
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arXiv:2601.22967v1 Announce Type: cross Abstract: Microbes constantly interact with their environment by depleting and transforming food sources. Theoretical studies have mainly focused on Lotka-Volterra models, which do not account for food source dynamics. In contrast, consumer-resource models, which consider food source dynamics, are less explored. In particular, it is still unclear what physical mechanisms control oscillatory dynamics at a single population level, a phenomenon which can only be captured by a consumer-resource model. Here, we present a minimalistic consumer-resource model of a single microbial population with growth and death dynamics, consuming a continuously replenishing substrate. Our model reveals that decaying oscillations can occur around steady state if and only if the timescale of microbial adaptation to food supply changes exceeds the death timescale. This interplay of timescales allows us to rationalize the emergence of oscillatory dynamics when adding various biophysical ingredients to the model. We find that microbial necromass recycling or complementary use of multiple food sources reduces the parameter range for oscillations and increases the decay rate of oscillations. Requiring multiple simultaneous food sources has the opposite effect. Essentially, facilitating growth reduces the likelihood of oscillations around a fixed point. We further demonstrate that such damped oscillatory behavior is correlated with persistent oscillatory behavior in a noisy environment. We hope our work will motivate further investigations of consumer-resource models to improve descriptions of environments where food source distributions vary in space and time.
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https://arxiv.org/abs/2601.22967
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ff5f435542deb7e956a01c2700883ce419594ab0b1691806f2cab61725fdc362
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2026-02-02T00:00:00-05:00
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Role of quasi-Fermi levels in Si- and Mg-related optical absorption in nitride laser diodes (LDs): material context
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arXiv:2601.22973v1 Announce Type: cross Abstract: Optical absorption and reabsorption of light emitted from active regions in nitride laser diodes (LDs) have been shown to reduce the light extraction efficiency of these devices. It was proven that the presence of Si and Mg may considerably increase the optical absorption. This effect is much stronger in the high-energy (short-wavelength) range of the spectrum. The absorption increase is directly related to the ionization of the Si donor and Mg acceptor levels, which are controlled by the electron and hole quasi-Fermi levels. It is shown that the absorption may be increased because of the higher ionization of Mg caused by the compensation in the p-type region and the high ionization of Si in the n-type region. It was explained theoretically why optical efficiency is increased by removal of doping in waveguides. It was also shown that good material quality leads to a low absorption level, especially in the Mg-doped p-type part of the device.
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https://arxiv.org/abs/2601.22973
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f22c9cad1a94e9126504a1793e2f8d45226e192976a3c0dc52c260c2f34ad12f
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2026-02-02T00:00:00-05:00
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Unlocking the Power of Orbital-Free Density Functional Theory to Explore the Electronic Structure Under Extreme Conditions
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arXiv:2601.23002v1 Announce Type: cross Abstract: Recent advances in X-ray free-electron laser diagnostics have enabled direct probing of the electronic structure under extreme pressures and temperatures, such as those encountered in stellar interiors and inertial confinement fusion experiments, challenging theoretical models for interpreting experimental data. Kohn-Sham density functional theory (KSDFT) has been successfully applied to analyze experimental X-ray scattering measurements, but its high computational cost renders routine application impractical. Orbital-free DFT (OFDFT) is a substantially more efficient alternative, with computational cost scaling linearly with system size and a weak temperature dependence, yet it often lacks the accuracy required for electronic structure description. Overcoming this limitation, we present a non-empirical Kohn-Sham-assisted orbital-free density functional framework for calculations at extreme conditions, which enables efficient OFDFT simulations with KSDFT-level accuracy for electron densities, electron-ion structure factors, and equations of state across a broad range of conditions. Benchmark comparisons with quantum Monte Carlo data for dense hydrogen and validation against Rayleigh weight measurements of hot dense beryllium demonstrate the reliability of the framework and speedups of up to several hundred times compared with KSDFT. We further show that even at temperatures on the order of 100 eV, quantum non-locality remains essential for correctly describing the electronic structure of dense hydrogen.
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https://arxiv.org/abs/2601.23002
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2c16e2eebe0980bc9490e5a51e70f3bfe5bbaef21519c561151208d79b0ccc6c
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2026-02-02T00:00:00-05:00
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High-resolution tunable frequency beamsplitter enabled by an integrated silicon pulse shaper
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arXiv:2601.23028v1 Announce Type: cross Abstract: We demonstrate high-fidelity, tunable, and ultrafine-resolution on-chip frequency beamsplitters using a quantum frequency processor based on an integrated pulse shaper with six spectral channels. Near-ideal Hadamard gate performance is achieved, with fidelity F > 0.9995 and modified success probability P > 0.9621 maintained across frequency spacings from 2-5 GHz and down to as few as four spectral pulse shaper channels. The system's support of frequency spacings as narrow as 2 GHz significantly surpasses prior bulk demonstrations and enables arbitrary splitting ratios via spectral phase or modulation index control. These results establish a scalable and resource-efficient platform for integrated frequency-bin quantum photonics, opening new directions in quantum information processing, including densely parallel single-qubit operations and multidimensional gate implementations.
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https://arxiv.org/abs/2601.23028
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14da1f65d7b58b578161625c779c1785b7e9bcfe3eb8e01fbbe047a1019b9d75
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2026-02-02T00:00:00-05:00
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Scalable Memory Sharing in Photonic Quantum Memristors for Reservoir Computing
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arXiv:2601.23044v1 Announce Type: cross Abstract: Although photons are robust, room-temperature carriers well suited to quantum machine learning, the absence of photon-photon interactions hinder the realization of memory functionalities that are critical for capturing long-range context. Recently, measurement-based implementations of photonic quantum memristors (PQMRs) have enabled tunable non-Markovian responses. However, their memory remains confined to local elements, in contrast to biological or artificial networks where memory is shared across the system. Here, we propose a scalable PQMR network that enables measurement-based memory sharing. Each memristive node updates its internal state using the history of its own and neighbouring quantum states, thereby realizing distributed memory. By modelling each node as a photonic quantum memtransistor, we demonstrate pronounced enhancements in both classical and quantum hysteresis at the device level, as well as enhanced network-level quantum hysteresis. Implemented as a quantum reservoir, the architecture achieves improved Fashion-MNIST classification accuracy and confidence via increased data separability. Our approach paves the way toward high-capacity quantum machine learning using memristive devices compatible with linear-optical quantum computing.
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https://arxiv.org/abs/2601.23044
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3092133f058c3499e3605e73fcbc193f0528a1a306c00f24b689e4c7c43258cb
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2026-02-02T00:00:00-05:00
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Establishing Earth's Matter Effect in Atmospheric Neutrino Oscillations at IceCube DeepCore
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arXiv:2601.23047v1 Announce Type: cross Abstract: The discovery of the non-zero value of $\theta_{13}$ has opened an exciting opportunity to probe the Earth's matter effects in three-flavor oscillations of atmospheric neutrinos. These matter effects depend on both neutrino energy and the electron density distributions encountered during their propagation through Earth. In this contribution, we present preliminary sensitivities from the DeepCore detector, a densely instrumented sub-array of the IceCube neutrino observatory at the South Pole, demonstrating its ability to observe these matter effects in atmospheric neutrino oscillations. Using simulated data equivalent to 9.3 years of observations at IceCube DeepCore, we show the sensitivity of the DeepCore to reject the vacuum oscillation hypothesis and align with the Preliminary Reference Earth Model. Additionally, we present the expected improvement in sensitivity for rejecting the vacuum oscillations using the upcoming IceCube Upgrade, a low-energy extension of the IceCube detector.
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https://arxiv.org/abs/2601.23047
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8a26a70000e92b692052d1ab102db83a2b033d91887ead42abb947ecd0e6d8f9
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2026-02-02T00:00:00-05:00
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Rotating Magnetocaloric Effect in Sintered La(Fe,Mn,Si)$_{13}$H$_z$ Plates
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arXiv:2601.23056v1 Announce Type: cross Abstract: La-Fe-Si-based alloys are among the most application-ready magnetocaloric materials for room-temperature magnetic refrigeration. Powder metallurgy methods have been previously demonstrated to successfully produce structures with sub-mm features for magnetic refrigerators in a scalable method. In this work, we explore the rotating magnetocaloric effect (RMCE) present in a 0.27 mm thin plate of sintered and hydrogenated La(Fe,Mn,Si)$_{13}$. The high aspect ratio ($\sim$50) of the thin plate leads to an anisotropic magnetocaloric effect (MCE), dependent on the relative orientation of the external magnetic field, and an RMCE when the external field is rotated. We find a maximum rotating adiabatic temperature change ($\Delta T_{ad}^{rot}$) of 1.17 K with the rotation of a 1 T magnetic field and 1.12 K when rotating a 0.6 T magnetic field, a reduction of only 4% for a 40% reduction in applied field strength. Magnetostatic computations revealed a considerable rotating isothermal entropy change ($\Delta S_{iso}^{rot}$), comparable to the conventional MCE of Gd for similar fields, reaching 3.97 J K$^{-1}$ kg$^{-1}$ for 1 T and 3.68 J K$^{-1}$ kg$^{-1}$ for 0.6 T (7% reduction), highlighting La-Fe-Mn-Si alloys as high potential candidates for a magnetic refrigerator based on the RMCE utilizing relatively low external magnetic field amplitudes, such as 0.6 T.
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https://arxiv.org/abs/2601.23056
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ef6479ddb0ce79e4f45e20d3bae3ec71cc0cf41b3da550e799dcd1b49392d730
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2026-02-02T00:00:00-05:00
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Exploring Layered Structure Inside Earth Using Atmospheric Neutrino Oscillation at IceCube DeepCore
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arXiv:2601.23057v1 Announce Type: cross Abstract: The IceCube detector, using its densely instrumented center, called DeepCore, can detect multi-GeV atmospheric neutrinos. The oscillation pattern of neutrinos is altered due to interactions with ambient electrons as they pass through Earth. The changes in these patterns are influenced by the amount of matter and its specific arrangement. As neutrinos propagate, they retain information about the densities they encounter. Our study demonstrates that IceCube DeepCore can utilize the Earth's matter effects to distinguish between a homogeneous matter density profile and a layered structure density profile of Earth. In this contribution, we present that IceCube DeepCore data equivalent to 9.3 years of observation can reject the homogeneous matter density profile with a confidence level of 1.4$\sigma$.
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https://arxiv.org/abs/2601.23057
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7b3e5e5042e48912e235579f0351867c4a4028ede2e1e37c20fe39108ebd7978
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2026-02-02T00:00:00-05:00
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Study of the internal structure of the Earth using neutrino oscillations at IceCube DeepCore
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arXiv:2601.23079v1 Announce Type: cross Abstract: Earth's mass and internal structure have been primarily studied through gravitational and seismic methods. Neutrinos, however, offer an independent way to explore Earth's interior via matter effects in neutrino oscillations that depend on the electron distribution inside Earth, and hence its matter density. Our study uses atmospheric neutrinos at DeepCore, a densely instrumented sub-detector of the IceCube Neutrino Observatory, to estimate Earth's mass and layer densities. We also assess how the upcoming IceCube Upgrade, with denser instrumentation, could improve these measurements.
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https://arxiv.org/abs/2601.23079
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d1c12cae65f203f69b6a2433c09be874479e33e31c6a03166a1f23fb391595c4
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2026-02-02T00:00:00-05:00
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Exploring Long-Range Interactions in the Atmospheric Neutrino Oscillations at IceCube DeepCore
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arXiv:2601.23093v1 Announce Type: cross Abstract: The IceCube neutrino observatory consists of an array of Digital Optical Modules (DOMs) instrumenting one cubic-kilometer of deep glacial ice at the South Pole. DeepCore, a densely-spaced sub-array of DOMs at the bottom central region of IceCube, enables the detection of atmospheric neutrinos with an energy threshold in the GeV range. The high statistics data of DeepCore provides a unique opportunity to perform neutrino oscillation studies as well as explore various sub-leading Beyond the Standard Model (BSM) physics signatures. We consider a well-motivated minimal extension of the Standard Model by an additional anomaly-free, gauged lepton-number symmetry, such as $L_e - L_\mu$ or $L_e - L_\tau$. These symmetries give rise to flavor-dependent long-range interaction mediated through a very light neutral gauge boson. In this contribution, we present the sensitivity of the IceCube DeepCore detector to search for this flavor-dependent long-range interaction potential with a runtime of 9.3 years.
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https://arxiv.org/abs/2601.23093
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d4d5b14e1eb02d10062e8dc8a2773001e1e185c6c1e08fb5e1efa306fdf6c8e7
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2026-02-02T00:00:00-05:00
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Loop-gap resonators achieving strong magnon-photon coupling in magnetic insulator thin films
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arXiv:2601.23123v1 Announce Type: cross Abstract: Magnon-photon hybrid systems consisting of a three-dimensional electromagnetic resonator and a bulk magnetic insulator constitute the standard experimental platform in cavity magnonics. Here, we demonstrate a modular loop-gap resonator design optimized to couple with thin films of magnetic insulators. We achieve the strong-coupling regime using this loop-gap resonator coupled to a 75~nm-thick epitaxial film of yttrium iron garnet at room temperature. We further show how to perform field-differential spectroscopy of the hybrid magnon-photon system, which eliminates the unwanted signal from other loop-gap modes uncoupled to the magnetic film. In addition to the uniform ferromagnetic resonance mode, the loop-gap resonator enables an hybridization with the standing spin-wave modes forming across the thickness of the film. Our approach unlocks the use of epitaxial films and multilayers of magnetic insulators to tune the magnon band structure in cavity magnonics experiments.
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https://arxiv.org/abs/2601.23123
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81c3fef4353635725b57bac5c38ac1db9e79c15b873fcc174fe95e1ed03372f6
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2026-02-02T00:00:00-05:00
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Human versus Artificial Inteligence; a significant example in astrophysics, alas
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arXiv:2601.23205v1 Announce Type: cross Abstract: There are two well documented models of gamma ray bursts (GRBs), the "Standard' model and the "Cannonball" model. They have often been reviewed [1] and sometimes compared [2]. Here, to avoid understandable biases, I show below the results of an experiment: letting an AI compare the data and the two models. All of what follows (but two references, two footnotes and the next sentence) is the result of asking Perplexity.ai to perform this confrontational task. It should be easy for an impartial reader to reach very clear conclusions.
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https://arxiv.org/abs/2601.23205
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3b8170236d2e5b99b0177fb55ae45b2c2d3fc8792582935fc25ed5b8cf527cfd
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2026-02-02T00:00:00-05:00
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High-gain effects in broadband continuous-wave parametric down conversion sources and measurements with undetected photons
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arXiv:2601.23263v1 Announce Type: cross Abstract: We study theoretically how high-gain effects affect the measurement outcome of visible signal spectra in undetected photon measurement schemes. We consider two interferometric configurations: firstly, the SU(1,1) interferometer where the idler incurs loss and additional dispersion in between two identical, lossless, squeezers; secondly, the induced coherence interferometer where the idler incurs loss and additional dispersion in between two identical, lossless, squeezers and where the second squeezer is seeded by the idler and a vacuum ancilla mode. Furthermore, we consider a distributed loss configuration where the idler incurs loss as it propagates in the nonlinear medium. Motivated by experimental evidence and due to the fact that broadband sources are ideal for these measurement schemes, we use the dispersive data of a third-order dispersion engineered integrated waveguide parametric down conversion (PDC) source presented in New Journal of Physics 26, 123025 (2024) to model the PDC spectra in the three configurations. For each configuration we consider the case of idler-only (i) absorption, (ii) additional dispersion, and (iii) the combined effects. We obtain results which outline the strength and weaknesses of the different configurations at different operation points.
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https://arxiv.org/abs/2601.23263
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0c396e726d81f9b554df3571b20849d546c64fcb48ec91ac08fcc68ec856fbe9
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2026-02-02T00:00:00-05:00
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Self-Arresting and Runaway Earthquakes:Nucleation, Propagation, Gutenberg-Richter law and Dragon-King Events
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arXiv:2402.14626v2 Announce Type: replace Abstract: We develop a dissipation-based framework for earthquake rupture on homogeneous faults that explicitly separates the onset of unstable slip from the conditions required for self-sustained rupture propagation. This distinction explains the coexistence of self-arresting earthquakes and run-away ruptures (subshear and supershear events) observed in numerical simulations and empirical studies. We identify two distinct characteristic fault sizes: a nucleation radius controlling the instability of slip, and in general a larger propagation radius controlling whether an unstable rupture can be energetically sustained. Ruptures initiated above the nucleation scale but below the propagation scale spontaneously arrest. We further derive the Gutenberg-Richter law for self-arresting earthquakes by linking rupture physics to the fractal geometry of faulting. Finally, we interpret run-away ruptures as extreme events generated by an amplifying mechanism, consistent with the dragon-king concept. These results provide a unified physical basis for earthquake initiation, arrest, and seismicity statistics.
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https://arxiv.org/abs/2402.14626
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e291a92d42f1c41aafa7d8814d8bc83dfc8c867352bf0fcbbbb2377726364fe2
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2026-02-02T00:00:00-05:00
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Purcell-enhanced solid-state laser cooling
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arXiv:2407.19601v2 Announce Type: replace Abstract: We show that Purcell effect can lead to a substantial enhancement in the maximum cooling power for solid-state laser cooling. We numerically demonstrate such enhancement in a patterned slot-waveguide structure using ytterbium-doped silica as the active material. The enhancement arises primarily from the increase of saturation power density and the escape efficiency, and can persist in spite of the presence of parasitic absorption in the structure surrounding the active material. Our results point to a new opportunity in photonic structure design for optical refrigeration.
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https://arxiv.org/abs/2407.19601
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494b9df8ff1cbff4d5262d6376be98c260d0dc676e8e95b1425af71600b6f43b
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2026-02-02T00:00:00-05:00
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Modularity maximization and community detection in complex networks through recursive and hierarchical annealing in the D-Wave Advantage quantum processing units
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arXiv:2410.07744v3 Announce Type: replace Abstract: Quantum adiabatic optimization has long been expected to outperform classical methods in solving NP-type problems. While this has been proven in certain experiments, its main applications still reside in academic problems where the size of the system to be solved would not represent an obstacle to any modern desktop computer. Here we develop a systematic procedure to find the global optima of the modularity function to discover community structure in complex networks solely relying on pure annealers rather than hybrid solutions. We bypass the one-hot encoding constraints by hierarchically and recursively encoding binary instances of the problem that can be solved without the need to guess the exact penalties for the Lagrange multipliers. We study the variability, and robustness of the annealing process as a function of network size, directness of connections, topology, and the resolution of the communities. We show how our approach produces meaningful and at least equally optimal solutions to state-of-the-art community detection algorithms while maintaining tractable computing times. Lastly, due to its recursive nature, the annealing process returns intermediate subdivisions thus offering interpretable rather than black-box solutions. These \textit{dendrograms} can be used to unveil normal and pathological hidden hierarchies in brain networks hence opening the door to clinical workflows. Overall, this represents a first step towards an applicable practice-oriented usage of pure quantum annealing potentially bridging two segregated communities in modern science and engineering; that of network science and quantum computing.
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https://arxiv.org/abs/2410.07744
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3a1717cb835cddc5b3785fc742dcb7033c0acc1b20012a36b91429227da9e40a
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2026-02-02T00:00:00-05:00
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Navigating permanent underdetermination in dark energy and inflationary cosmology
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arXiv:2501.13521v2 Announce Type: replace Abstract: We identify troubling cases of so-called `permanent underdetermination' in both dark energy and inflationary cosmology. We bring to bear (a) a taxonomy of possible responses to underdetermination, and (b) an understanding of both dark energy and inflationary cosmology from an effective field theory point of view. We argue that, under certain conditions, there are viable responses which can arguably alleviate at least some of the concerns about underdetermination in the dark energy and inflationary sectors. However, the epistemic threat of permanent underdetermination remains a significant challenge.
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https://arxiv.org/abs/2501.13521
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41f0455560cf7503dba8776e9864239575036bcd42f15e48d39ae4d7a74b4ba1
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2026-02-02T00:00:00-05:00
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SPARKX: A Software Package for Analyzing Relativistic Kinematics in Collision Experiments
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arXiv:2503.09415v2 Announce Type: replace Abstract: SPARKX is an open-source Python package developed to analyze simulation data from heavy-ion collision experiments. By offering a comprehensive suite of tools, SPARKX simplifies data analysis workflows, supports multiple formats such as OSCAR2013, and integrates seamlessly with SMASH and JETSCAPE/X-SCAPE. This paper describes SPARKX's architecture, features, and applications and demonstrates its effectiveness through detailed examples and performance benchmarks. SPARKX enhances productivity and precision in relativistic kinematics studies.
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https://arxiv.org/abs/2503.09415
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6aa7d09ab5c96a6454da184b095743d94066166907185d30780ed759d7d92763
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2026-02-02T00:00:00-05:00
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CaloHadronic: a diffusion model for the generation of hadronic showers
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arXiv:2506.21720v2 Announce Type: replace Abstract: Simulating showers of particles in highly-granular calorimeters is a key frontier in the application of machine learning to particle physics. Achieving high accuracy and speed with generative machine learning models can enable them to augment traditional simulations and alleviate a major computing constraint. Recent developments have shown how diffusion based generative shower simulation approaches that do not rely on a fixed structure, but instead generate geometry-independent point clouds, are very efficient. We present a transformer-based extension to previous architectures which were developed for simulating electromagnetic showers in the highly granular electromagnetic calorimeter of the International Large Detector, ILD. The attention mechanism now allows us to generate complex hadronic showers with more pronounced substructure across both the electromagnetic and hadronic calorimeters. This is the first time that machine learning methods are used to holistically generate showers across the electromagnetic and hadronic calorimeter in highly granular imaging calorimeter systems.
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https://arxiv.org/abs/2506.21720
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2c8795c7040ab8338e61c09cc47c9836e66539c19446d2ffe3bfc0a5559c161b
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2026-02-02T00:00:00-05:00
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The Dynamics of the Transverse Optical Flux in Random Media
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arXiv:2507.13195v2 Announce Type: replace Abstract: We study the evolution of the kinetic energy (or gradient norm) of an incident linearly polarized monochromatic wave propagating in correlated random media. We explore the optical flux transverse to the mean Poynting flux at the paraxial-nonparaxial (vectorial) transition along with vortex counting. Here, by paraxial-nonparaxial transition we mean a gradual loss of validity of the paraxial approximation such that it is necessary to solve Maxwell-consistently employing the dyadic Green's function. The vortex number appears to increase approximately with a cubic root of the propagation distance for sufficiently small correlation length. Furthermore, a kink appears in nucleation rate at the position of maximum scintillation upon increasing correlation length. A driven steady state is reached due to the filtering of evanescent waves upon propagation. Finally, we present the spectrum of the incompressible kinetic energy and how it evolves from the paraxial case to that of a (nonparaxial) random field.
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https://arxiv.org/abs/2507.13195
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1281a4bd5c424b25ca74fbe99a1b5283d463fa312a781cb68d1c91f764f5929d
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2026-02-02T00:00:00-05:00
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SPIDER: Scalable Probabilistic Inference for Differential Earthquake Relocation
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arXiv:2508.12117v2 Announce Type: replace Abstract: Seismicity catalogs are larger than ever due to an explosion of techniques for enhanced earthquake detection and an abundance of high-quality datasets. Bayesian inference is an appealing framework for locating earthquakes due to its ability to propagate and quantify uncertainty into the inversion results, but traditional methods do not scale well to high-dimensional parameter spaces, making them unsuitable for double-difference relocation where the number of parameters can reach the millions. Here we introduce SPIDER, a scalable Bayesian inference framework for double-difference hypocenter relocation. SPIDER uses a physics-informed neural network Eikonal solver together with a highly efficient sampler called Stochastic Gradient Langevin Dynamics to generate posterior samples jointly for entire seismicity catalogs. We show that traditional double-difference relocation formulations neglect residual correlation between observations with common events, which biases uncertainty estimates. Our formulation is designed to whiten this residual correlation, and is readily parallelized over multiple GPUs for enhanced computational efficiency. We demonstrate the capabilities of SPIDER on a rigorous synthetic seismicity catalog and three real data catalogs from California and Japan. We introduce several ways to analyze high-dimensional posterior distributions to aid in scientific interpretation and evaluation.
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https://arxiv.org/abs/2508.12117
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921893929b8be6bfcd4fc90ae666c3712fe225b20e668bcccd63aa180aae6a8c
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2026-02-02T00:00:00-05:00
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Towards a better understanding of abdominal wall biomechanics: in vivo relationship between dynamic intra-abdominal pressure and magnetic resonance imaging measurements
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arXiv:2508.12827v2 Announce Type: replace Abstract: Background In vivo mechanical behaviour of the abdominal wall has been poorly characterised and important details are missing regarding the occurrence and post-operative recurrence rate of hernias which can be as high as 30 %. This study aimed to assess the correlation between abdominal wall displacement and intra-abdominal pressure, as well as abdominal compliance. Methods Eighteen healthy participants performed audio-guided passive (breathing) and active (coughing, Valsalva maneuver) exercises. Axial dynamic changes of abdominal muscles and visceral area were measured using MRI, and intra-abdominal pressure with ingested pressure sensor. Findings Correlations between abdominal wall displacement and intra-abdominal pressure were specific to participant, exercise, and varying between rectus abdominis and lateral muscles. Strong correlations were found between rectus abdominis displacement and intra-abdominal pressure during breathing (r = 0.92 $\pm$ 0.06), as well as lateral muscles displacement with intra-abdominal pressure during coughing and Valsalva maneuver (r = --0.98 $\pm$ 0.03 and -- 0.94 $\pm$ 0.05 respectively). The abdominal pseudo-compliance varied greatly among participants during muscular contraction, the coefficient of variation reaching up to 70 %. Interpretation The combination of intra-abdominal pressure and dynamic MRI measurements enables the identification of participant-specific behaviour pattern. Intra-abdominal pressure and abdominal wall dynamic undergo consistent and predictable interactions. However, this relationship is subject-specific and may not be extrapolated to other individuals. Therefore, both intra-abdominal pressure and abdominal wall motion must be measured in the same participant in order to accurately characterise the abdominal wall behaviour. These results are of great importance for mesh design, surgical decision-making, and personalised healthcare.
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https://arxiv.org/abs/2508.12827
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cb510336903dc526954ef75580ab77d45720c91bb20d62b73849c4f1bf555923
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2026-02-02T00:00:00-05:00
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Bayesian Optimisation of Non-linear Breit-Wheeler Pair Production in Simulated Laser Experiments
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arXiv:2508.16533v2 Announce Type: replace Abstract: High laser intensities enable the production of electron-positron pairs from bright gamma rays passing through strong fields. Potentially the most promising approach for all-optical experiments in the near term uses dense but higher divergence electron beams from laser wakefield acceleration to produce gamma rays through inverse Compton scattering. Achieving many-photon collisions between these gamma rays and the high intensity laser pulse in practice is extremely difficult, however, due to significant shot-to-shot jitter in laser pointing and timing. We model these practical difficulties using simulated Monte-Carlo experiments. By using a more efficient algorithm for sampling infrequent pair production with particle splitting, we enable the exploration of a multi-dimensional parameter space. Using Gaussian Process Regression we then efficiently find optimal conditions for maximising pair production by changing the laser spot size, the energy in the colliding beam, and the stand-off distance between the laser wakefield accelerator and the focus of the colliding laser pulse. We find that the optimal stand-off distance increases with the degree of laser jitter and that the best conditions for producing electron-positron pairs are not the same as the best conditions for maximising the energy in the gamma rays. With \unit[100]{J} of laser energy, we estimate rates of pair production of around 1 pair per 100 electrons are achievable even with jitter of 10s of microns and 10s of femtoseconds.
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https://arxiv.org/abs/2508.16533
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a4aa663a01ff98c95f5f36ac669ff681dae18d63ff5e849c146d035e9796615f
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2026-02-02T00:00:00-05:00
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Laser-induced Coulomb explosion of the LiI molecule and of its dimer
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arXiv:2509.06458v2 Announce Type: replace Abstract: A gas-phase sample consisting of lithium iodide, $\mathrm{LiI}$, molecules and their dimer $\mathrm{(LiI)}_2$, are Coulomb exploded by an intense 25 femtosecond laser pulse. In the case of $\mathrm{LiI}$, we focus on the double ionization that creates a pair of $\mathrm{Li}^+$ and $\mathrm{I}^+$ recoil ions. From the kinetic energy distribution of the $\mathrm{Li}^+$ ions, extracted using coincidence filtering, we determine the distribution of internuclear distances $P(R)$ via the ground state potential curve of $\mathrm{LiI}^{2+}$ obtained from an ab initio calculation that accounts for non-Coulombic effects. We find that the center of $P(R)$ is close to the expected internuclear separation based on the three vibrational states of $\mathrm{LiI}$ populated, whereas the width of $P(R)$ exceeds the theoretical value by $\sim$ 52 %. We discuss if fragmentation via excited $\mathrm{LiI}^{2+}$ potential curves affects the determination of $P(R)$. In the case of the dimer, $\mathrm{(LiI)}_2$, we observe kinetic energies and relative emission directions of $\mathrm{Li}^+$, $\mathrm{I}^+$, and $\mathrm{I}^{2+}$ recoil ions consistent with Coulomb explosion of the parallelogram-shaped dimer after removing up to six electrons by the laser pulse.
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https://arxiv.org/abs/2509.06458
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682a3d0ceaf9a52709498e987920ebcfeaa535450d957d2449cb96fb5ec0848d
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2026-02-02T00:00:00-05:00
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Comparing Simulated and Observed Particle Energy Distributions through Magnetic Reconnection in Earth's Magnetotail
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arXiv:2509.07621v2 Announce Type: replace Abstract: Magnetic reconnection is an explosive process that accelerates particles to high energies in Earth's magnetosphere, offering a unique natural laboratory to study this phenomenon. This study investigates how well data-driven fully kinetic simulations can reproduce the ion and electron energy distributions observed during a reconnection event by the Magnetospheric Multiscale (MMS) mission.We performed fully kinetic 2D simulations initialized with plasma parameters derived from the MMS event and compared the resulting ion and electron energy distributions with observations. Key numerical and physical parameters were systematically varied to assess their influence on the resulting particle spectra. The simulations capture the overall shape and evolution of nonthermal energy distributions for both species, but generally underestimate the very high-energy tail of the electron spectrum. Variations in numerical parameters have negligible effects on the resulting spectra, while the initial upstream temperatures instead play a more pronounced role in reproducing the observed distributions.We present a novel analysis of data-driven fully kinetic simulations of MR, showing that key aspects of particle acceleration can be captured, while also highlighting the limitations of 2D simulations and the need for more realistic (e.g., 3D) setups to reproduce the observed particle energization accurately.
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https://arxiv.org/abs/2509.07621
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ee0943c40bd65e6ad3265dce847e1c43db9fa6abfed4f59a109af6d90de58843
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2026-02-02T00:00:00-05:00
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Instability of the halocline at the North Pole
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arXiv:2509.21378v2 Announce Type: replace Abstract: In this paper we address the issue of stability for the near-inertial Pollard waves, as a model for the halocline in the region of the Arctic Ocean centered around the North Pole, derived in Puntini (2025a). Adopting the short-wavelength instability approach, the stability of such flows reduces to study the stability of a system of ODEs along fluid trajectories, leading to the result that, when the steepness of the near-inertial Pollard waves exceeds a specific threshold, those waves are linearly unstable. The explicit dispersion relation of the model allows to easily compute such threshold, knowing the physical properties of the water column.
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https://arxiv.org/abs/2509.21378
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f9300790fbf596221a95f3ac0f447a2891cb87bb98f41d300956164bb69afd27
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2026-02-02T00:00:00-05:00
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Investigating Solid-Fluid Phase Coexistence in DC Plasma Bilayer Crystals: The Role of Particle Pairing and Mode Coupling
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arXiv:2510.09491v3 Announce Type: replace Abstract: This article presents a detailed investigation of solid-fluid phase coexistence in a bilayer dusty plasma crystal subjected to varying confinement ring bias voltages in a DC glow discharge argon plasma. Melamine formaldehyde particles were employed to form a stable, hexagonally ordered bilayer crystal within a confinement ring electrically isolated from the grounded cathode. By systematically adjusting the confinement ring bias, a distinct phase coexistence emerged characterized by a fluid-like melted core surrounded by a solid crystalline periphery. Crucially, analysis of the phonon spectra revealed frequency shifts that deviate significantly from the predictions of classical monolayer Mode-Coupling Instability (MCI) theory. Stability analysis further demonstrated that dynamic interlayer particle pairing and the associated increase in non-reciprocal interaction strength are strongly correlated with the onset of structural destabilization. These findings highlight previously underappreciated mechanisms driving the melting transition in bilayer dusty plasmas, offering a more comprehensive understanding of phase behavior in complex plasma systems. The results underscore the importance of interlayer coupling and confinement effects in tuning structural transitions.
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https://arxiv.org/abs/2510.09491
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65229d0d98f3579dd410ab6d93c8277355472984ecb8ce82a9155876d494c6bf
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2026-02-02T00:00:00-05:00
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Predictive Dosimetry in PSMA-Targeted Radiopharmaceutical Therapies: A PBPK Modeling and Machine Learning Study
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arXiv:2510.21054v4 Announce Type: replace Abstract: Predictive dosimetry is central to enabling personalized radiopharmaceutical therapy (RPT), particularly in prostate specific membrane antigen (PSMA) targeted theranostics. In this work, we develop a three layer computational framework that integrates physiologically based pharmacokinetic (PBPK) modeling with machine learning (ML) to predict both physical (AUC, absorbed dose) and biological (BED, EQD2) dosimetric endpoints in tumors and major organs. In the first layer, we generated 640 virtual patients using PBPK simulations of F-18, Ga-68, and Cu-64 labeled PSMA PET tracers paired with Lu-177 PSMA therapy, producing 15360 tumor and organ time activity curves (TACs) under realistic biological variability and PET-like noise. In the second layer, TACs were transformed into quantitative kinetic features and mapped to physical and biological dose metrics. In the third layer, ML models (Random Forest, Extra Trees, Ridge, Gradient Boosting, and XGBoost) were trained to predict RPT doses from PET derived features, with performance evaluated using mean absolute percentage error (MAPE) and R2. Cu-64 PSMA-617 based PET yielded the most robust predictions, achieving tumor dose MAPE as low as 8 percent and 10 to 20 percent for normal organs, while F-18 DCFPyL showed volume dependent performance and Ga-68 PSMA-11 exhibited higher variability. SHAP analysis revealed that peak uptake, clearance, and early kinetic features dominated predictive performance across organs and endpoints. This PBPK ML framework enables scalable, physiology informed predictive dosimetry and provides a foundation for trial design and patient specific treatment planning in PSMA targeted RPT. These results demonstrate that pre therapy PET can serve as a reliable surrogate for post therapy dosimetry, enabling scalable personalization of PSMA targeted RPT.
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https://arxiv.org/abs/2510.21054
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c81bc3002b3aad8e78b5a00f3ae862b9aee2c01e317a92ee917ca2836ebae077
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2026-02-02T00:00:00-05:00
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Reactive capacitance of flat patches of arbitrary shape
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arXiv:2510.25288v2 Announce Type: replace Abstract: We investigate the capacity of a flat partially reactive patch of arbitrary shape to trap independent particles that undergo steady-state diffusion in the three-dimensional space. We focus on the total flux of particles onto the patch that determines its reactive capacitance. To disentangle the respective roles of the reactivity and the shape of the patch, we employ a spectral expansion of the reactive capacitance over a suitable Steklov eigenvalue problem. We derive several bounds on the reactive capacitance to reveal its monotonicity with respect to the reactivity and the shape. Two probabilistic interpretations are presented as well. An efficient numerical tool is developed for solving the associated Steklov spectral problem for patches of arbitrary shape. We propose and validate, both theoretically and numerically, a simple, fully explicit approximation for the reactive capacitance that depends only on the surface area and the electrostatic capacitance of the patch. This approximation opens promising ways to access various characteristics of diffusion-controlled reactions in general domains with multiple small well-separated patches. Direct applications of these results in statistical physics and physical chemistry are discussed.
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https://arxiv.org/abs/2510.25288
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3254086fa54696a0c7e30d15cf4715cc1554a295d2088d1822dd9c6a09d8cf07
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2026-02-02T00:00:00-05:00
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Optimized tandem catalyst patterning for CO$_2$ reduction flow reactors
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arXiv:2511.07638v3 Announce Type: replace Abstract: Tandem catalysis involves two or more catalysts arranged in proximity within a single reaction vessel, with the aim of synergistically aligning the catalysts' reaction pathways to maximize overall system performance. This study presents a proof of concept showing the integration of continuum transport modeling with design optimization in a simplified two-dimensional flow reactor setup for electrochemical CO$_2$ reduction. Ag catalysts provide the CO$_2$ $\rightarrow$ CO reaction capability, and Cu catalysts provide the CO $\rightarrow$ high-value products reaction capability. Given a set of input parameters, the optimization algorithm uses adjoint methods to modify the Ag/Cu surface patterning in order to maximize the current density toward high-value products, such as ethylene. The optimized designs yield significant performance enhancement especially at more negative applied voltages (i.e., stronger surface reactions) and for larger numbers of patterning sections. For an applied voltage of $-1.7$ V vs. SHE, the $12$-section optimized design increases the current density towards ethylene by up to $65$% compared to the unoptimized $2$-section design. For the optimized cases, observed differences in the production and consumption of CO (the key intermediate species) and minimized zones of low CO reactant surface concentration on Cu sections explain the improved reactor performance.
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https://arxiv.org/abs/2511.07638
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2026-02-02T00:00:00-05:00
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Beam-test evaluation of pre-production Low Gain Avalanche Detectors for the ATLAS High Granularity Timing Detector
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arXiv:2512.01855v2 Announce Type: replace Abstract: The High Granularity Timing Detector (HGTD) will be installed in the ATLAS experiment as part of the Phase-II upgrade for the High Luminosity-Large Hadron Collider (HL-LHC). It will mitigate pile-up effects in the forward region, and measure per bunch luminosity. The design of HGTD is based on Low Gain Avalanche Detector (LGAD) sensors. This paper presents the results of beam-test campaigns conducted at CERN and DESY in 2023 and 2024 on single LGADs from HGTD pre-production test structures, before and after neutron irradiation up to fluences of $2.5 \times 10^{15}~\mathrm{n_{eq}/cm^2}$. The tested LGADs can meet HGTD requirements in terms of charge collection, time resolution, and hit efficiency, even under HL-LHC end-of-life conditions, supporting their deployment in the final detector.
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https://arxiv.org/abs/2512.01855
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ccf96057a723e1ec3e8396bebb47a31e37cb55deb6a209eefa11d9248518ed07
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2026-02-02T00:00:00-05:00
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Formative experience for intensive instruction physics courses: Evaluation and results in an Electromagnetism course
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arXiv:2512.12404v2 Announce Type: replace Abstract: The rising demand for higher education has led universities to offer courses in multiple formats, including Intensive Instruction Courses (IICs), to meet the needs of a diverse student body. While active teaching methods improve physics understanding in standard courses, little research has examined their effectiveness in IICs. This research explored the most efficient methodologies for promoting meaningful learning in intensive physics courses. To this end, an integrated pedagogical proposal was designed based on the opinions gathered from a focus group of teachers with previous experience teaching these courses, as well as on existing literature, highlighting methodologies, types of assessment, and characteristics of ICCs. To evaluate its efficiency, a quasi-experiment was conducted in which students were divided into two groups: an experimental group (EG), which followed the teaching proposal, and a control group (CG), which received non-innovated lessons. Results were measured using the BEMA electromagnetism concepts inventory before and after the intervention. Statistical analysis revealed that Hake's Gain was greater in the EG, both in general terms and in each thematic unit of the course. The intervention in the EG showed that the use of active methodologies was more efficient than those used in the CG in the context of IICs. The results obtained suggest the need to continue investigating other factors involved in the teaching-learning process of IICs.
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https://arxiv.org/abs/2512.12404
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4dfb30a97fc29f3286b0c4a28c5fe3c22fbf4f37f9b88a803fd80eca6ef05a83
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2026-02-02T00:00:00-05:00
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Laser interferometry as a robust neuromorphic platform for machine learning
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arXiv:2601.18047v2 Announce Type: replace Abstract: We present a method for implementing an optical neural network using only linear optical resources, namely field displacement and interferometry applied to coherent states of light. The nonlinearity required for learning in a neural network is realized via an encoding of the input into phase shifts allowing for far more straightforward experimental implementation compared to previous proposals for, and demonstrations of, $\textit{in situ}$ inference. Beyond $\textit{in situ}$ inference, the method enables $\textit{in situ}$ training by utilizing established techniques like parameter shift rules or physical backpropagation to extract gradients directly from measurements of the linear optical circuit. We also investigate the effect of photon losses and find the model to be very resilient to these.
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https://arxiv.org/abs/2601.18047
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b67a4f8fe767cd1c1d3f2928214f49f3fd327e77e22a5613e4d5ebb0ecd4d023
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2026-02-02T00:00:00-05:00
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On-chip control of the coherence matrix of four-mode partially coherent light: rank, entropy, and modal Stokes parameters
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arXiv:2601.18797v2 Announce Type: replace Abstract: Partially coherent light offers salutary capabilities in optical information processing that cannot be matched by coherent light. To date, this `coherence advantage' has been confirmed in proof-of-principle optical communications protocols using bulk optics. Taking full advantage of such opportunities necessitates processing multimode partially coherent light in integrated photonics platforms that alone provide the requisite stability for cascaded operations on a large scale. Here we demonstrate on-chip manipulation of four-mode partially coherent light described by a $4\times4$ Hermitian coherence matrix. Starting with generic maximally incoherent light, we utilize an on-chip hexagonal mesh of Mach-Zehnder interferometers to perform all the unitary and non-unitary tasks that are critical for realizing structured coherence: controlling the coherence rank (the number of non-zero eigenvalues of the coherence matrix); tuning the field entropy; molding the structure of the coherence matrix via $4\times4$ unitary transformations constructed out of sequences of $2\times2$ unitaries acting on pairs of modes; and tomographic reconstruction of the coherence matrix by measuring the modal Stokes parameters associated with Kronecker-Pauli matrices. These results confirm the scalability of utilizing $2\times2$ on-chip building blocks for the synthesis and reconstruction of high-dimensional coherence matrices, and provide a decisive step towards large-scale on-chip manipulation of massively moded partially coherent light for applications in optical information processing.
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https://arxiv.org/abs/2601.18797
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70efcda2a48b51190b6f0838d3eba025a6dd127b674a19e4a305f578c70a1dd3
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2026-02-02T00:00:00-05:00
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Spectroscopy of $^4$He at 0.25 ppt Uncertainty and Improved Alpha-Helion Charge-Radius Difference Determination
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arXiv:2601.19444v2 Announce Type: replace Abstract: High-precision spectroscopy of simple atomic systems can be used to advance the theory of atomic energy levels but can also serve as a sensitive probe of nuclear charge radii. For this last purpose, we report an improved measurement of the $2\,^3{S}_1 \to 2\,^1{S}_0$ transition frequency in $^4$He with 48 Hz uncertainty (0.25 ppt), using a Bose-Einstein condensed sample confined in a magic-wavelength optical dipole trap. A systematic Doppler shift from condensate motion is suppressed by time-resolved ion detection, and the transition frequency is calibrated via a White Rabbit link to a remote active hydrogen maser clock. Combined with previous $^3$He measurements and improved theory, we obtain the most precise determination to date of the charge-radius difference between the helion and alpha particle ($r_{h}^2 -r_{\alpha}^2$) of $1.0676(10)\text{fm}^2$. This is consistent with other recent determinations and confirms that the current discrepancy between QED theory and experimentally observed ionization energies of excited states in helium is not apparent in the isotope shift.
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https://arxiv.org/abs/2601.19444
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6028e433ac0644e8dcefabe962b3a91690087bafc71ecaf4c71f45ba45133936
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2026-02-02T00:00:00-05:00
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Reverse Energy Flows in Two-Dimensional Photonic Crystals and Analogies with Vortex Formation and Analogous Flows in Hydrodynamics
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arXiv:2601.21704v2 Announce Type: replace Abstract: This paper examines the connection between photonic band-gap formation in two types of two-dimensional photonic crystals and the emergence of reverse electromagnetic energy flows generated by linearly polarized plane waves incident on a photonic-crystal slab. We show that these reverse energy flows, observed in both transmitted and reflected fields, originate from vortex structures in the Poynting vector. The resulting energy-flow patterns exhibit striking analogies to vortex formation in fluid motion past obstacles. The geometry and dynamics of the Poynting-vector vortices determine whether the incident electromagnetic energy is impeded, leading to the formation of photonic band gaps, or instead guided through the structure, enabling transmission.
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https://arxiv.org/abs/2601.21704
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9366671834699d2a141b4b41a084a460fb2ebdc8ad4da2134d50b7bffd7cadae
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2026-02-02T00:00:00-05:00
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On the statistical analysis of grouped data: when Pearson $\chi^2$ and other divisible statistics are not goodness-of-fit tests
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arXiv:2406.09195v5 Announce Type: replace-cross Abstract: Thousands of experiments are analyzed and papers are published each year involving the statistical analysis of grouped data. While this area of statistics is often perceived -- somewhat naively -- as saturated, several misconceptions still affect everyday practice, and new frontiers have so far remained unexplored. Researchers must be aware of the limitations affecting their analyses and what are the new possibilities in their hands. Motivated by this need, the article introduces a unifying approach to the analysis of grouped data, which allows us to study the class of divisible statistics -- that includes Pearson's $\chi^2$, the likelihood ratio as special cases -- with a fresh perspective. The contributions collected in this manuscript span from modeling and estimation to distribution-free goodness-of-fit tests. Perhaps the most surprising result presented here is that, in a sparse regime, all tests proposed in the literature are dominated by members of the class of weighted linear statistics.
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https://arxiv.org/abs/2406.09195
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5de2e69887c5401cb006dc42c4c6312d76114a9091151323c78ae3d5c818e7cc
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2026-02-02T00:00:00-05:00
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Clever algorithms for glasses work by time reparametrization
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arXiv:2409.17121v2 Announce Type: replace-cross Abstract: The ultraslow dynamics of glass-formers has been explained by two views considered as mutually exclusive: one invokes locally hindered mobility, the other rests on the complexity of the configuration space. Here we demonstrate that the evolution responds strongly to the details of the dynamics by changing the speed of time-flow: it has time-reparametrization softness. This finding reconciles both views: while local constraints reparametrize the flow of time, the global landscape determines relationships between different correlations at the same times. We show that modern algorithms developed to accelerate the relaxation to equilibrium act by changing the time reparametrization. Their success thus relies on their ability to exploit reparametrization softness. We conjecture that these results extend beyond the realm of glasses to the optimization of more general constraint satisfaction problems and to broader classes of algorithms.
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https://arxiv.org/abs/2409.17121
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e1548d0368798509b7708d89b5e86b8d75e15e3890f851c97861ded8f8d65ba9
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2026-02-02T00:00:00-05:00
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Quantum Circuits for the Metropolis-Hastings Algorithm
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arXiv:2506.11576v5 Announce Type: replace-cross Abstract: Szegedy's quantization of a reversible Markov chain provides a quantum walk whose spectral gap is quadratically larger than that of the classical walk. Quantum computers are therefore expected to provide a speedup of Metropolis-Hastings (MH) simulations. Existing generic methods to implement the quantum walk require coherently computing the transition probabilities of the underlying Markov kernel. However, reversible computing methods require a number of qubits that scales with the complexity of the computation. This overhead is undesirable in near-term fault-tolerant quantum computing, where few logical qubits are available. In this work, we present a Szegedy quantum walk construction which follows the classical proposal-acceptance logic, and does not require further reversible computing methods. We also compare this construction with an alternative to Szegedy's approach which also provides a quadratic gap amplification. Since each step of the quantum walks uses a constant number of proposal and acceptance steps, we expect the end-to-end quadratic speedup to hold for MH Markov Chain Monte-Carlo simulations.
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https://arxiv.org/abs/2506.11576
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8a1d4df908c64282e2fdbd770185c1e351e1596e40f83fb1921f674d96472cd2
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2026-02-02T00:00:00-05:00
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Learning to flock in open space by avoiding collisions and staying together
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arXiv:2506.15587v2 Announce Type: replace-cross Abstract: We investigate the emergence of cohesive flocking in open, boundless space using a multi-agent reinforcement learning framework. Agents integrate positional and orientational information from their closest topological neighbours and learn to balance alignment and attractive interactions by optimizing a local cost function that penalizes both excessive separation and close-range crowding. The resulting Vicsek-like dynamics is robust to algorithmic implementation details and yields cohesive collective motion with high polar order. The optimal policy is dominated by strong aligning interactions when agents are sufficiently close to their neighbours, and a flexible combination of alignment and attraction at larger separations. We further characterize the internal structure and dynamics of the resulting groups using liquid-state metrics and neighbour exchange rates, finding qualitative agreement with empirical observations in starling flocks. These results suggest that flocking may emerge in groups of moving agents as an adaptive response to the biological imperatives of staying together while avoiding collisions.
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https://arxiv.org/abs/2506.15587
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86508195c322a5c2ad56813aa1bc5b1a39d129acc995f975509cc1b308a8c3f2
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2026-02-02T00:00:00-05:00
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Projective Transformations for Regularized Central-Force Dynamics: Hamiltonian Formulation
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arXiv:2506.22681v5 Announce Type: replace-cross Abstract: This work introduces a Hamiltonian approach to regularization and linearization of central-force particle dynamics through a new canonical extension of the so-called "projective decomposition". The regularization scheme is formulated within the framework of classic analytical Hamiltonian dynamics as a redundant-dimensional canonical/symplectic coordinate transformation, combined with an evolution parameter transformation, on extended phase space. By considering a generalized version of the standard projective decomposition, we obtain a family of such canonical transformations which differ at the momentum level. From this family of transformations, a preferred coordinate set is chosen that possesses a simple and intuitive connection to the particle's local reference frame. Using this transformation, closed-form solutions are readily obtained for inverse-square and inverse-cubic radial forces, or any superposition thereof. Governing equations are numerically validated for the classic two-body problem incorporating the J2 gravitational perturbation.
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https://arxiv.org/abs/2506.22681
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b834908397ba6c127cf45258c2e6c725be978a73f5e31f9fdb85fd5ad5c9f196
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2026-02-02T00:00:00-05:00
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Perturbed Toroidal Vortices Display Internal Simply Connected Topology
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arXiv:2507.04596v2 Announce Type: replace-cross Abstract: This work shows that the interiors of perturbed zero-helicity vortices display simply connected topology with a crescent-shaped boundary. Flux surfaces in fluid and magnetic vortices were explored analytically, while particle trajectories in the context of plasma confinement were examined numerically, demonstrating the existence of both toroidal and simply connected topologies. This new topology appears for perturbations in a broad class, with amplitudes and spatial variance allowed to be arbitrarily small. This work proves the closedness of field lines under odd-parity perturbations of zero-helicity vortices.
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https://arxiv.org/abs/2507.04596
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8b938d19a32c35f9f3f9464a528b428400f3624179180a56555b5c4b58f79cf2
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2026-02-02T00:00:00-05:00
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Conformal prediction for uncertainties in nucleon-nucleon scattering
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arXiv:2507.08085v3 Announce Type: replace-cross Abstract: Conformal prediction is a distribution-free and model-agnostic uncertainty-quantification method that provides finite-sample prediction intervals with guaranteed coverage. In this work, for the first time, we apply conformal-prediction to generate uncertainty bands for physical observables in nuclear physics, such as the total cross section and nucleon-nucleon phase shifts. We demonstrate the method's flexibility by considering three scenarios: (i) a pointwise model, where expansion coefficients in chiral effective field theory are treated as random variables; (ii) a Gaussian-process model for the coefficients; and (iii) phase shifts at various energies and partial waves calculated using local interactions from chiral effective field theory. In each case, conformal-prediction intervals are constructed and validated empirically. Our results show that conformal prediction provides reliable and adaptive uncertainty bands even in the presence of non-Gaussian behavior, such as skewness and heavy tails. These findings highlight conformal prediction as a robust and practical framework for quantifying theoretical uncertainties.
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https://arxiv.org/abs/2507.08085
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0541c23493d69444467ca8818e8a0fcc7bd27b6b00bfe0d98e41f363a21c532f
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2026-02-02T00:00:00-05:00
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Jitter Sensing and Control for Multi-Plane Phase Retrieval
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arXiv:2508.09256v2 Announce Type: replace-cross Abstract: The family of multi-plane phase retrieval sensors, such as the curvature and nonlinear curvature wavefront sensors (WFS), contain tip/tilt information embedded in their signals. We have built a nonlinear curvature WFS to study different wavefront reconstruction methods and test the ability to extract tip/tilt information. Using reliable and fast centroiding algorithms, combined with knowledge of the measured $z$-distance to each measurement plane, we demonstrate that image jitter may be sensed and compensated for using a fast steering mirror and the WFS in closed loop. This approach obviates the need for peripheral components such as quad-cells or access to a separate scientific imaging channel. Our laboratory experiments validate tip/tilt estimation and correction using nlCWFS data, achieving tip/tilt accuracy of +/-0.1, lambda/D for an unaberrated beam and better than ~+/-0.5, lambda/D in the presence of aberrations, consistent with prior numerical simulations. We further demonstrate a closed-loop tip/tilt control implementation and show a qualitative improvement in the stability and overall quality of multi-plane phase retrieval reconstructions.
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https://arxiv.org/abs/2508.09256
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7d08b75fdbcadb11e38e69beb59b077cfff09c8b655da1a34a9f2832716e721b
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2026-02-02T00:00:00-05:00
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The Three-Body Limit Cycle: Universal Form for General Regulators
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arXiv:2509.04746v2 Announce Type: replace-cross Abstract: The Efimov effect, a remarkable realization of discrete scale invariance, emerges in the three-body problem with short-range interactions and is understood as a renormalization group (RG) limit cycle within Short-Range Effective Field Theory (SREFT). While the analytic form of the three-body renormalization relation has been established for a sharp cutoff regulator, its universality for other regulators remains underexplored. In this work, we derive the universal functional form of the three-body renormalization relation for general separable regulators through a detailed analysis of the Skorniakov-Ter-Martirosian and Faddeev equations. We find that the relation follows from a real M\"{o}bius transformation characterized by three parameters. This universality is verified numerically for various regulators. Although the functional form remains the same, the parameters characterizing the limit cycle exhibit regulator dependence. These findings broaden the class of RG limit cycles in SREFT and offer a more complete understanding of three-body renormalization.
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https://arxiv.org/abs/2509.04746
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0c93a2cdaee0aae48a9e7de4593fa1098caea05665aecb8b12e5dc55551acf87
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2026-02-02T00:00:00-05:00
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Automatic Model Extraction of the Match Standard in Symmetric--Reciprocal--Match Calibration
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arXiv:2509.18426v2 Announce Type: replace-cross Abstract: This paper addresses the modeling of parasitics of the match standard in the symmetric-reciprocal-match (SRM) calibration method of vector network analyzers (VNAs). In the general SRM procedure, the match standard is assumed to be fully known. Here, we demonstrate that the match can be modeled with an arbitrary frequency-dependent model using a non-linear global optimization procedure. To highlight the validity of the suggested approach, numerical tests were conducted, demonstrating the ability to recover the match standard parasitic model down to software numerical precision. Additionally, we performed microstrip line measurements to compare the SRM calibration with match modeling to the multiline thru-reflect-line (TRL) calibration one, showing that automatic model extraction can achieve accuracy similar to using a match standard defined through multiline TRL calibration.
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https://arxiv.org/abs/2509.18426
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54bf7d5fc880b14b0af99da6de9ef5de3ac491b8f81e4fe64855aaf5e6318eb4
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2026-02-02T00:00:00-05:00
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Hydrodynamic Simulations of Tidal Disruption Encores
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arXiv:2510.23729v2 Announce Type: replace-cross Abstract: We present hydrodynamic simulations with the moving-mesh code AREPO of Tidal Disruption Encores (TDEEs) in nuclear star clusters (NSCs). TDEEs arise when a stellar-mass black hole (sBH) disrupts a star within the NSC, producing debris that is unbound from the sBH but remains gravitationally bound to the central massive black hole (MBH), leading to a delayed secondary flare. We find that the morphology and thermodynamics of the fallback material depend sensitively on the disruption geometry, MBH mass, and sBH-MBH separation. We identify two distinct morphological outcomes: ring encores, where debris circularize into a torus, and direct encores, where streams plunge toward the MBH, with encore luminosities peaking at times corresponding to the freefall timescale and one orbital period, respectively. Across all simulated cases, we find these events exhibit luminosities of $10^{40}-10^{42}$ erg/s with lightcurves characteristic of their morphology. Our work greatly improves the predictions of TDEE lightcurves and empowers observations to probe into NSC dynamics and sBH population while providing possible explanations for anomalous TDE-like flares.
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https://arxiv.org/abs/2510.23729
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4668603ca97a1e0d13defd73feb76e5eedaca15634b19e08cf05946e5b124eb1
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2026-02-02T00:00:00-05:00
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Dissipative quantum algorithms for excited-state quantum chemistry
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arXiv:2512.19870v2 Announce Type: replace-cross Abstract: Electronic excited states are central to a vast array of physical and chemical phenomena, yet accurate and efficient methods for preparing them on quantum devices remain challenging and comparatively underexplored. We introduce a general dissipative algorithm for selectively preparing ab initio electronic excited states. The key idea is to recast excited-state preparation as an effective ground-state problem by suitably modifying the underlying Lindblad dynamics so that the target excited state becomes the unique steady state of a designed quantum channel. We develop three complementary strategies, tailored to different types of prior information about the excited state, such as symmetry and approximate energy. We demonstrate the effectiveness and versatility of these schemes through numerical simulations of atomic and molecular spectra, including valence excitations in prototypical planar conjugated molecules and transition-metal complexes. Taken together, these results provide a new pathway for advancing quantum simulation methods for realistic strongly correlated electronic systems.
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https://arxiv.org/abs/2512.19870
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226205f94c2b5c57168c491b2f61316f5c74b7d7f19a6eb685df3668d5a179a0
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2026-02-02T00:00:00-05:00
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Quantum Fisher information analysis for absorption measurements with undetected photons
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arXiv:2601.16941v2 Announce Type: replace-cross Abstract: We theoretically compare the quantum Fisher information (QFI) for three configurations of absorption spectroscopy with undetected idler photons: an SU(1,1) interferometer with inter-source idler loss, an induced-coherence (IC) setup in which the idler partially seeds a second squeezer together with a vacuum ancilla, and a distributed-loss (DL) scheme with in-medium attenuation. We calculate the QFI as a function of parametric gain for both full and signal-only detection access. For losses below 99% and low to moderate gain, the SU(1,1) configuration provides the largest QFI. At high gain and intermediate loss, the IC scheme performs best, while under extreme attenuation (transmission $<$ 1%) the DL model becomes optimal. These results delineate the measurement regimes in which each architecture is optimal in terms of information theory.
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https://arxiv.org/abs/2601.16941
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8da297c9bc1bf4f4c47f08c10965db541f4f960f4e94e6484243dfdff3702029
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2026-02-02T00:00:00-05:00
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On a square packing conjecture of Erd\H{o}s
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arXiv:2601.22163v1 Announce Type: new Abstract: Let $f(n)$ be the maximum sum of the sides of non-overlapping squares (or equilateral triangles) packed inside a unit square or (unit equilateral triangle). In this paper, we explore some properties of $f$ and examine how the square and triangle cases are similar. We prove that a conjecture of Erd\H{o}s, which says that $f(k^2+1) = k$ for all $k$, is equivalent to the convergence of the series $\sum_{k\geqslant 1}(f(k^2+1)-k)$. We also explore the case of parallelograms and discuss how that is similar to the case of unit square and triangle.
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https://arxiv.org/abs/2601.22163
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d54f21b710c5fbe108b267d0e30f99bdc0ad365b6ca639066ff3f4e50289cee5
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2026-02-02T00:00:00-05:00
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Some new results on the Seidel energy of graphs with self-loops
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arXiv:2601.22165v1 Announce Type: new Abstract: Harshitha et al. recently introduced Seidel energy of graphs with self loops. In this paper, we extend some of their results by giving a necessary and sufficient condition for the Seidel energy of a looped graph to be equal to the Seidel energy of its underlying graph. We also consider Seidel energy of the union of certain graphs, and show that graph operations complement and Seidel switching preserve Seidel energy in the looped setting.
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https://arxiv.org/abs/2601.22165
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9eb55503b31db331c4e764695e963205a3c2ee856bf8c66e28b645407a0e485a
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2026-02-02T00:00:00-05:00
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Pseudo-Riemannian Spectral Triples for $\mathrm{SU}(1,1)$
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arXiv:2601.22171v1 Announce Type: new Abstract: We use the harmonic analysis of $\mathrm{SU}(1,1)$ to show that the triple $(\mathcal{A},\mathcal{H},D)$, with $D$ (the closure of) Kostant's cubic Dirac operator acting on the Hilbert space $\mathcal{H}=L^2(\mathrm{SU}(1,1))\otimes\mathbb{C}^2$, and with $*$-algebra $\mathcal{A}=C^\infty_c(\mathrm{SU}(1,1))\otimes 1$, forms both a pseudo-Riemannian spectral triple in the sense of Van den Dungen, Paschke and Rennie, and an indefinite spectral triple in the sense of Van den Dungen and Rennie.
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https://arxiv.org/abs/2601.22171
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877a451d84990927deb6c34f6e65d2880a8305f06623b073ad830b29db6016fd
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2026-02-02T00:00:00-05:00
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A root finding method with arbitrary order of convergence
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arXiv:2601.22187v1 Announce Type: new Abstract: Let $a\in \mathbb{R}^{+}\backslash\left\{0\right\}$ and $M\in\mathbb{N}$. We consider the equation $t^M-a=0$, which is equivalent to $1-\frac{t^M}{a}=0\,.$ The real solution is $\sqrt[M]{a}$. In this publication, we present a method that enables the calculation of $\sqrt[M]{a}$ with arbitrary order of convergence using only polynomials. We define the fixed point function \[ F\left(x\right) =\prod_{\ell=1}^{P}\left(1+\frac{1}{\ell\cdot M}\right) \int\limits_{0}^{x}\!\left(1-{\frac{{t}^{M}}{a}}\right)^{P}{\rm d}t =\sum\limits_{k=0}^{P}\frac{\left(-1\right)^{\,k}}{a^{\,k}}\cdot\binom{P}{k}\cdot\frac{x^{\,k\,\cdot M+1}}{k\,\cdot M+1} \] This is a polynomial of degree $\left(P\cdot M+1\right)$ with $\left(P+1\right)$ terms. The calculation of $\sqrt[M]{a}$ is thus reduced to a polynomial evaluation. The computational tests we performed demonstrate the efficiency of the method. -- Es sei $a\in \mathbb{R}^{+}\backslash\left\{0\right\}$ und $M\in\mathbb{N}$. Vorgelegt ist die Gleichung $t^M-a=0$, die \"aquivalent zu $1-\frac{t^M}{a}=0$ ist. Die reelle L\"osung hiervon ist $\sqrt[M]{a}$. In dieser Ver\"offentlichung stellen wir ein Verfahren vor, das die Berechnung von $\sqrt[M]{a}$ mit beliebiger Konvergenzordnung erm\"oglicht und nur Polynome verwendet. Wir definieren die Fixpunktfunktion \[F\left(x\right) =\prod_{\ell=1}^{P}\left(1+\frac{1}{\ell\cdot M}\right) \int\limits_{0}^{x}\!\left(1-{\frac{{t}^{M}}{a}}\right)^{P}{\rm d}t =\sum\limits_{k=0}^{P}\frac{\left(-1\right)^{\,k}}{a^{\,k}}\cdot\binom{P}{k}\cdot\frac{x^{\,k\,\cdot M+1}}{k\,\cdot M+1} \] Das ist ein Polynom vom Grad $\left(P\cdot M+1\right)$ mit $\left(P+1\right)$ Summanden. Anhand ausgew\"ahlter Beispiele von Wurzelberechnungen zeigen wir die Effizienz des Verfahrens.
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https://arxiv.org/abs/2601.22187
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2026-02-02T00:00:00-05:00
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When is the convolution a t-norm on normal, convex and upper semicontinuous fuzzy truth values?
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arXiv:2601.22190v1 Announce Type: new Abstract: In Type-2 rule-based fuzzy systems (T2 RFSs), triangular norms on complete lattice $(\mathbf{L},\sqsubseteq)$ or $(\mathbf{L_u},\sqsubseteq)$ can be used to model the compositional rule of inference, where $\textbf{L}$ is the set of all convex normal fuzzy truth values, $\mathbf{L_u}$ is the set of all convex normal and upper semicontinuous fuzzy truth values, and $\sqsubseteq$ is the so-called convolution order. Hence, the choice of t-norms on $(\mathbf{L},\sqsubseteq)$ or $(\mathbf{L_u},\sqsubseteq)$ may influence the performance of T2 RFSs, and thus, it is significant to broad the set of t-norms among which domain experts can choose most suitable one. To construct t-norms on $(\mathbf{L},\sqsubseteq)$ or $(\mathbf{L_u},\sqsubseteq)$, the mainstream method is based on convolution $\ast_\vartriangle$ induced by two operators $\ast$ and $\vartriangle$ on the unit interval $[0,1]$. Recently, we have complete solve the question when convolution $\ast_\vartriangle$ is a t-norm on $(\mathbf{L},\sqsubseteq)$. This paper aim to provide the necessary and sufficient conditions under which convolution $\ast_\vartriangle$ is a t-norm on $(\mathbf{L_u}, \sqsubseteq)$.
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https://arxiv.org/abs/2601.22190
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b0fdef653c1dc5582c0cf947892b9896d906e5fc1e6b9ed4a8c8d6be17a73b40
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2026-02-02T00:00:00-05:00
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Zero-level integrable modules over twisted affine Lie superalgebras
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arXiv:2601.22210v1 Announce Type: new Abstract: The main result of this paper is the characterization of zero-level integrable finite weight modules, over twisted affine Lie superalgebras. We prove that such a module is parabolically induced from a module which is obtained, in a prescribed way, from a module over a Lie algebra $\mathscr{L}$ which is either a $\bbbz$-graded abelian Lie algebra or a direct sum of a $\bbbz$-graded abelian Lie algebra and the so-called quadratic Lie superalgebra $\mathcal{Q}$. We give also a complete characterization of both finite dimensional simple $\mathcal{Q}$-modules as well as bounded finite weight $\bbbz$-graded simple $\mathcal{Q}$-modules.
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https://arxiv.org/abs/2601.22210
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Academic Papers
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9a7b573957e3a840885ca9b5680fa4bef668b93c67552b3cc28bdb03140d4482
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2026-02-02T00:00:00-05:00
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The metaplectic semigroup and its applications to time-frequency analysis and evolution operators
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arXiv:2601.22252v1 Announce Type: new Abstract: We develop a systematic analysis of the metaplectic semigroup $\mathrm{Mp}_+(d,\mathbb{C})$ associated with positive complex symplectic matrices, a notion introduced almost simultaneously and independently by H\"ormander, Brunet, Kramer, and Howe, thereby extending the classical metaplectic theory beyond the unitary setting. While the existing literature has largely focused on propagators of quadratic evolution equations, for which results are typically obtained via Mehler formulas, our approach is operator-theoretic and symplectic in spirit and adapts techniques from the standard metaplectic group $\mathrm{Mp}(d,\mathbb{R})$ to a substantially broader framework that is not driven by differential problems or particular propagators. This point of view provides deeper insight into the structure of the metaplectic semigroup, and allows us to investigate its generators, polar decomposition, and intertwining relations with complex conjugation and with the Wigner distribution. We then exploit these structural results to characterize, from a metaplectic perspective, classes of time-frequency representations satisfying prescribed structural properties. Finally, we discuss further implications for parabolic equations with complex quadratic Hamiltonians, we study the boundedness of their propagators on modulation spaces, we obtain estimates in time of their operator norms. Finally, we apply our theory to the study of propagation of Wigner singularities.
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https://arxiv.org/abs/2601.22252
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Academic Papers
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e973898becf180c43966098599c5acb9c6c31b3c2d7876e34b1ee8f82fe32a83
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2026-02-02T00:00:00-05:00
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Smooth correspondences between quiver varieties
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arXiv:2601.22287v1 Announce Type: new Abstract: We introduce a new class of smooth correspondences between Nakajima quiver varieties called split parabolic quiver varieties, and study their properties. We use these correspondences to construct an explicit resolution of singularities of quiver Brill--Noether loci and prove that the latter are irreducible and Cohen-Macaulay of expected dimension (if non-empty). This generalizes the results of Nakajima--Yoshioka and Bayer--Chen--Jiang for Hilbert schemes of points on surfaces.
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https://arxiv.org/abs/2601.22287
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Academic Papers
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8e4430471f177afca4681ba58649d5721cf7575ebd6b1079e2380fa676631f78
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2026-02-02T00:00:00-05:00
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Operating Imperfect AI: Reliability Drift and Human Congestion
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arXiv:2601.22295v1 Announce Type: new Abstract: The deployment of machine learning in high-stakes services relies on ``human-in-the-loop'' architectures to mitigate algorithmic uncertainty. However, existing static policies fail to address a fundamental tension: algorithms suffer from stochastic ``reliability drift,'' while human override capacity is scarce and congestible. We formulate the management of such systems as a dynamic queueing control problem. The system state is defined by the tuple (queue backlog, reliability regime), and the control variable is a state-dependent risk threshold. We prove that the optimal escalation policy is driven by the endogenous ``Shadow Price of Capacity.'' We establish two key structural monotonicity results: (i) Congestion Shedding, where the threshold rises with backlog to sacrifice marginal accuracy for responsiveness; and (ii) Safety Buffering, where the threshold lowers during drift to use the queue as a ``risk capacitor.'' Furthermore, we identify a critical ``Capacity Phase Transition'' in the arrival-drift parameter space, beyond which no policy can maintain safety standards without causing structural system failure (infinite queues). Our results provide rigorous operational rules for managing the interface between imperfect algorithms and congested experts.
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https://arxiv.org/abs/2601.22295
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Academic Papers
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svg
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f478409d699f13b332663cc1ad6791070cab9cdb5a461ee54ce984b90b862ed8
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2026-02-02T00:00:00-05:00
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The Homology of Complex Equivariant Bordism
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arXiv:2601.22303v1 Announce Type: new Abstract: Let $A$ be an abelian compact Lie group and let $E$ be an oriented $A$-spectrum. We compute the $E$-homology of tom Dieck's homotopical $A$-equivariant complex bordism spectrum $MU_A$ in two ways, correcting an error in Cole-Greenlees-Kriz (2002). Additionally, we calculate the $E$-homology of the geometric $A$-equivariant complex bordism spectrum $mU_A$.
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https://arxiv.org/abs/2601.22303
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Academic Papers
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37bc6c5a21795cbd4430242e1431e0788254df2ed984f9ee207bb3143c1a4218
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2026-02-02T00:00:00-05:00
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Geometric configuration of integrally closed Noetherian domains
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arXiv:2601.22314v1 Announce Type: new Abstract: In this paper, we completely describe the family of integrally closed Noetherian domains between $\mathbb{Z}[X]$ and $\mathbb{Q}[X]$. We accomplish this result by classifying the Krull domains between these two polynomial rings. To this end, we first describe the DVRs of $\mathbb{Q}(X)$ lying over $\mathbb{Z}_{(p)}$ for some prime $p \in \mathbb{Z}$, by distinguishing them according to whether the extension of the residue fields is algebraic or transcendental. We unify the known descriptions of such valuations by considering ultrametric balls in $\mathbb{C}_p$, the completion of the algebraic closure of the field $\mathbb{Q}_p$ of $p$-adic numbers. We then study when the intersection $R$ of such DVRs with $\mathbb{Q}[X]$ is of finite character, so that $R$ is a Krull domain, and we finally compute the divisor class group of $R$. It turns out that such a ring is formed by those polynomials which simultaneously map a finite union of ultrametric balls of $\mathbb{C}_p$ to its valuation domain $\mathbb{O}_p$, as $p\in\mathbb{Z}$ ranges through the set of primes. By a result of Heinzer, the Krull domains of this class are precisely the integrally closed Noetherian domains between $\mathbb{Z}[X]$ and $\mathbb{Q}[X]$. This novel approach provides a geometric understanding of this class of integrally closed domains. Furthermore, we also describe the UFDs between $\mathbb{Z}[X]$ and $\mathbb{Q}[X]$.
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https://arxiv.org/abs/2601.22314
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Academic Papers
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2e1caa4bfff4dae63fce88cbe595c2a6fec32c53c0c58da24fecd272f321909d
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2026-02-02T00:00:00-05:00
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Square Root-Factorized Covariance Steering
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arXiv:2601.22348v1 Announce Type: new Abstract: Covariance steering (CS) synthesizes a control policy which drives the state's mean and covariance matrix towards desired values. Offering tractable computation of a closed-loop policy which can obey chance constraints in uncertain environments, application to many real-world control problems have been proposed. We consider the chance-constrained, discrete-time, linear time-varying CS with Gaussian noise. The contribution of this paper is a novel solution method for this problem, explicitly writing the propagation equations of the Cholesky factor of the state covariance matrix by using the QR decomposition. The use of the square-root form of covariance matrices brings two key benefits over other existing methods: (i) computational scalability and (ii) numerical reliability. (i) Compared to solution methods that require large block matrix formulations, the proposed method scales better with the growth in horizon length, shows better optimality, and uses memoryless state feedback. (ii) Compared to another class of methods that explicitly define the covariance matrix as variables, the proposed method allows flexible cost formulations and shows better numerical reliability when uncertainty terms are smaller than the mean. On the other hand, these benefits come with a minor drawback: the propagation equation of covariance square roots is non-convex, necessitating sequential convex programming to solve. However, this paper proves the global optimality of the proposed approach for CS without chance constraints. When chance constraints are present, the existing optimal CS formulation is also non-convex, and we prove that the proposed approach shares the same local minima. We verify the mathematical arguments via extensive numerical simulations.
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https://arxiv.org/abs/2601.22348
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Academic Papers
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svg
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0270ceff567bd4362a58f401f58cb7e1182be1c3f5020bc4323a316868f78f5e
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2026-02-02T00:00:00-05:00
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Hermitian indices and factorization of selfadjoint operators on a Kre\u{i}n space
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arXiv:2601.22366v1 Announce Type: new Abstract: The hermitian indices of a selfadjoint operator $C$ on a Kre\u{i}n space $\mathcal H$ are defined as geometric measures of positivity and negativity of the operator. A different pair of indices arises in the Bogn\'ar-Kr\'amli factorization of $C$, which writes $C$ as a product $AA^*$ where $A$ acts on a Kre\u{i}n space $\mathcal A$ into $\mathcal H$ and has zero kernel; the new indices are the positive and negative indices of $\mathcal A$. Such factorizations are far from unique. When $\mathcal H$ is separable, it is known that the two notions of indices always coincide, and this has applications to index formulas in the theory of Julia operators and completion problems for operator matrices. A new proof of the equality of indices that does not require separability is given in this work.
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https://arxiv.org/abs/2601.22366
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Academic Papers
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svg
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59f1fc087d6ae9750bff20981620e2b5b3979fcf7e727e33ac6f0da60547acd3
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2026-02-02T00:00:00-05:00
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Dynamical stability of various convex graphical translators
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arXiv:2601.22368v1 Announce Type: new Abstract: In the first part of the paper, we prove the existence of longtime solution to mean curvature flow starting from a graph of a continuous function defined over a slab. Then, we establish dynamical stability results for various types of graphical translators to mean curvature flow, namely the grim reaper, two dimensional graphical translators, and asymptotically cylindrical translators.
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https://arxiv.org/abs/2601.22368
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Academic Papers
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svg
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4bdb16cb32aa1ae8b0fde43cbb48389cb955458d5eabd126651808d6bfc92d01
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2026-02-02T00:00:00-05:00
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Operator Splitting with Hamilton-Jacobi-based Proximals
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arXiv:2601.22370v1 Announce Type: new Abstract: Operator splitting algorithms are a cornerstone of modern first-order optimization, decomposing complex problems into simpler subproblems solved via proximal operators. However, most functions lack closed-form proximal operators, which has long restricted these methods to a narrow set of problems. Hamilton-Jacobi-based proximal operator (HJ-Prox) is a recent derivative-free Monte Carlo technique based on Hamilton-Jacobi PDE theory, that approximates proximal operators numerically. In this work, we introduce a unified framework for operator splitting via HJ-Prox, which allows for deployment of operator splitting even when functions are not proximable. We prove that replacing exact proximal steps with HJ-Prox in algorithms such as proximal point, proximal gradient descent, Douglas-Rachford splitting, Davis-Yin splitting, and primal-dual hybrid gradient preserves convergence guarantees under mild assumptions. Numerical experiments demonstrate HJ-Prox is competitive and effective on a wide variety of statistical learning tasks.
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https://arxiv.org/abs/2601.22370
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Academic Papers
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644763899531295b87d0e698f7d3ee2926bdb2aa54f72d36b4f8b93f9cfeae7f
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2026-02-02T00:00:00-05:00
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Visibility in Polygonal Environments with Holes: Finding Best Spots for Hiding and Surveillance
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arXiv:2601.22405v1 Announce Type: new Abstract: Visibility plays an important role for decision making in cluttered, uncertain environments. This paper considers the problem of identifying optimal hiding spots for an agent against line-of-sight detection by an adversary whose location is unknown. We consider environments modeled as polygons with holes. We develop a set of mathematical tools for reasoning about visibility as a function of position and rely on non-smooth analysis to formally characterize the regularity properties of various visibility-based metrics. These metrics are non-smooth and non-convex, so off-the-shelf optimization algorithms can only guarantee convergence to Clarke critical points. To address this, the proposed Normalized Descent algorithm leverages the structure of non-smooth points in visibility problems and introduces randomness to escape saddle points. Our technical analysis allows for the non-monotonic decrease in the visibility metric and strengthens the algorithm guarantees, ensuring convergence to local minima with high probability. Simulations on two hide-and-seek scenarios showcase the effectiveness of the proposed approach.
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https://arxiv.org/abs/2601.22405
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Academic Papers
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d8e13ec8c00794359100c5adc4b73f6bb70183397c32eeed66fbf1ce45393f6c
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2026-02-02T00:00:00-05:00
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Quasihomomorphisms to real algebraic groups
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arXiv:2601.22411v1 Announce Type: new Abstract: A quasihomomorphism is a map that satisfies the homomorphism relation up to bounded error. Fujiwara and Kapovich proved a rigidity result for quasihomomorphisms taking values in discrete groups, showing that all quasihomomorphisms can be built from homomorphisms and sections of bounded central extensions. We study quasihomomorphisms with values in real linear algebraic groups, and prove an analogous rigidity theorem.
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https://arxiv.org/abs/2601.22411
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Academic Papers
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