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2023-08-05
The isometric immersion of surfaces with finite total curvature
In this paper, we study the smooth isometric immersion of a complete simply connected surface with a negative Gauss curvature in the three-dimensional Euclidean space. For a surface with a finite total Gauss curvature and appropriate oscillations of the Gauss curvature, we prove the global existence of a smooth solutio...
2308.02832v2
2023-08-25
The time dimensional reduction method to determine the initial conditions without the knowledge of damping coefficients
This paper aims to reconstruct the initial condition of a hyperbolic equation with an unknown damping coefficient. Our approach involves approximating the hyperbolic equation's solution by its truncated Fourier expansion in the time domain and using a polynomial-exponential basis. This truncation process facilitates th...
2308.13152v1
2023-08-25
A Game of Bundle Adjustment -- Learning Efficient Convergence
Bundle adjustment is the common way to solve localization and mapping. It is an iterative process in which a system of non-linear equations is solved using two optimization methods, weighted by a damping factor. In the classic approach, the latter is chosen heuristically by the Levenberg-Marquardt algorithm on each ite...
2308.13270v1
2023-08-30
Stochastic Thermodynamics of Brownian motion in Temperature Gradient
We study stochastic thermodynamics of a Brownian particle which is subjected to a temperature gradient and is confined by an external potential. We first formulate an over-damped Ito-Langevin theory in terms of local temperature, friction coefficient, and steady state distribution, all of which are experimentally measu...
2308.15764v3
2023-09-04
Sphaleron damping and effects on vector and axial charge transport in high-temperature QCD plasmas
We modify the anomalous hydrodynamic equations of motion to account for dissipative effects due to QCD sphaleron transitions. By investigating the linearized hydrodynamic equations, we show that sphaleron transitions lead to nontrivial effects on vector and axial charge transport phenomena in the presence of a magnetic...
2309.01726v1
2023-09-05
Signatures and characterization of dominating Kerr nonlinearity between two driven systems with application to a suspended magnetic beam
We consider a model of two harmonically driven damped harmonic oscillators that are coupled linearly and with a cross-Kerr coupling. We show how to distinguish this combination of coupling types from the case where a coupling of optomechanical type is present. This can be useful for the characterization of various nonl...
2309.02204v2
2023-09-07
Strong coupling between WS$_2$ monolayer excitons and a hybrid plasmon polariton at room temperature
Light-matter interactions in solid-state systems have attracted considerable interest in recent years. Here, we report on a room-temperature study on the interaction of tungsten disulfide (WS$_2$) monolayer excitons with a hybrid plasmon polariton (HPP) mode supported by nanogroove grating structures milled into single...
2309.03560v1
2023-09-07
Neutron spin echo is a "quantum tale of two paths''
We describe an experiment that strongly supports a two-path interferometric model in which the spin-up and spin-down components of each neutron propagate coherently along spatially separated parallel paths in a typical neutron spin echo small angle scattering (SESANS) experiment. Specifically, we show that the usual se...
2309.03987v2
2023-09-07
An explicit multi-time stepping algorithm for multi-time scale coupling problems in SPH
Simulating physical problems involving multi-time scale coupling is challenging due to the need of solving these multi-time scale processes simultaneously. In response to this challenge, this paper proposed an explicit multi-time step algorithm coupled with a solid dynamic relaxation scheme. The explicit scheme simplif...
2309.04010v1
2023-09-15
Limiting absorption principles and linear inviscid damping in the Euler-Boussinesq system in the periodic channel
We consider the long-time behavior of solutions to the two dimensional non-homogeneous Euler equations under the Boussinesq approximation posed on a periodic channel. We study the linearized system near a linearly stratified Couette flow and prove inviscid damping of the perturbed density and velocity field for any pos...
2309.08445v2
2023-09-15
Breakdown of sound in superfluid helium
Like elementary particles carry energy and momentum in the Universe, quasiparticles are the elementary carriers of energy and momentum quanta in condensed matter. And, like elementary particles, under certain conditions quasiparticles can be unstable and decay, emitting pairs of less energetic ones. Pitaevskii proposed...
2309.08790v1
2023-09-18
Nonlinear dynamics and magneto-elasticity of nanodrums near the phase transition
Nanomechanical resonances of two-dimensional (2D) materials are sensitive probes for condensed-matter physics, offering new insights into magnetic and electronic phase transitions. Despite extensive research, the influence of the spin dynamics near a second-order phase transition on the nonlinear dynamics of 2D membran...
2309.09672v1
2023-09-21
Quantum State Reconstruction in a Noisy Environment via Deep Learning
Quantum noise is currently limiting efficient quantum information processing and computation. In this work, we consider the tasks of reconstructing and classifying quantum states corrupted by the action of an unknown noisy channel using classical feedforward neural networks. By framing reconstruction as a regression pr...
2309.11949v1
2023-09-27
Exploring antisymmetric tensor effects on black hole shadows and quasinormal frequencies
This study explores the impact of antisymmetric tensor effects on spherically symmetric black holes, investigating photon spheres, shadows, emission rate and quasinormal frequencies in relation to a parameter which triggers the Lorentz symmetry breaking. We examine these configurations without and with the presence of ...
2309.15778v3
2023-10-20
Exponential weight averaging as damped harmonic motion
The exponential moving average (EMA) is a commonly used statistic for providing stable estimates of stochastic quantities in deep learning optimization. Recently, EMA has seen considerable use in generative models, where it is computed with respect to the model weights, and significantly improves the stability of the i...
2310.13854v1
2023-10-23
Adam through a Second-Order Lens
Research into optimisation for deep learning is characterised by a tension between the computational efficiency of first-order, gradient-based methods (such as SGD and Adam) and the theoretical efficiency of second-order, curvature-based methods (such as quasi-Newton methods and K-FAC). We seek to combine the benefits ...
2310.14963v1
2023-10-24
Observation of Damped Oscillations in Chemical-Quantum-Magnetic Interactions
Fundamental interactions are the basis of the most diverse phenomena in science that allow the dazzling of possible applications. In this work, we report a new interaction, which we call chemical-quantum-magnetic interaction. This interaction arises due to the difference in valence that the Fe3O4/PANI nanostructure acq...
2310.15775v1
2023-10-26
Do Graph Neural Networks Dream of Landau Damping? Insights from Kinetic Simulations of a Plasma Sheet Model
We explore the possibility of fully replacing a plasma physics kinetic simulator with a graph neural network-based simulator. We focus on this class of surrogate models given the similarity between their message-passing update mechanism and the traditional physics solver update, and the possibility of enforcing known p...
2310.17646v2
2023-10-29
Impact of Medium Anisotropy on Quarkonium Dissociation and Regeneration
Quarkonium production in ultra-relativistic collisions plays a crucial role in probing the existence of hot QCD matter. This study explores quarkonia states dissociation and regeneration in the hot QCD medium while considering momentum anisotropy. The net quarkonia decay width ($\Gamma_{D}$) arises from two essential p...
2310.18909v1
2023-10-31
Stability threshold of nearly-Couette shear flows with Navier boundary conditions in 2D
In this work, we prove a threshold theorem for the 2D Navier-Stokes equations posed on the periodic channel, $\mathbb{T} \times [-1,1]$, supplemented with Navier boundary conditions $\omega|_{y = \pm 1} = 0$. Initial datum is taken to be a perturbation of Couette in the following sense: the shear component of the pertu...
2311.00141v1
2023-11-10
Moment expansion method for composite open quantum systems including a damped oscillator mode
We consider a damped oscillator mode that is resonantly driven and is coupled to an arbitrary target system via the position quadrature operator. For such a composite open quantum system, we develop a numerical method to compute the reduced density matrix of the target system and the low-order moments of the quadrature...
2311.06113v1
2023-11-22
Analytic formulas for the D-mode Robinson instability
The passive superconducting harmonic cavity (PSHC) scheme is adopted by several existing and future synchrotron light source storage rings, as it has a relatively smaller R/Q and a relatively larger quality factor (Q), which can effectively reduce the beam-loading effect and suppress the mode-one instability. Based on ...
2311.13205v1
2023-11-27
Learning Reionization History from Quasars with Simulation-Based Inference
Understanding the entire history of the ionization state of the intergalactic medium (IGM) is at the frontier of astrophysics and cosmology. A promising method to achieve this is by extracting the damping wing signal from the neutral IGM. As hundreds of redshift $z>6$ quasars are observed, we anticipate determining the...
2311.16238v1
2023-12-05
DemaFormer: Damped Exponential Moving Average Transformer with Energy-Based Modeling for Temporal Language Grounding
Temporal Language Grounding seeks to localize video moments that semantically correspond to a natural language query. Recent advances employ the attention mechanism to learn the relations between video moments and the text query. However, naive attention might not be able to appropriately capture such relations, result...
2312.02549v1
2023-12-05
THz-Driven Coherent Magnetization Dynamics in a Labyrinth Domain State
Terahertz (THz) light pulses can be used for an ultrafast coherent manipulation of the magnetization. Driving the magnetization at THz frequencies is currently the fastest way of writing magnetic information in ferromagnets. Using time-resolved resonant magnetic scattering, we gain new insights to the THz-driven cohere...
2312.02654v1
2023-12-07
Enhanced high-dimensional teleportation in correlated amplitude damping noise by weak measurement and environment-assisted measurement
High-dimensional teleportation provides various benefits in quantum networks and repeaters, but all these advantages rely on the high-quality distribution of high-dimensional entanglement over a noisy channel. It is essential to consider correlation effects when two entangled qutrits travel consecutively through the sa...
2312.03988v1
2023-12-11
Collisions and collective flavor conversion: Integrating out the fast dynamics
In dense astrophysical environments, notably core-collapse supernovae and neutron star mergers, neutrino-neutrino forward scattering can spawn flavor conversion on very short scales. Scattering with the background medium can impact collective flavor conversion in various ways, either damping oscillations or possibly se...
2312.07612v2
2023-12-15
Position-momentum conditioning, relative entropy decomposition and convergence to equilibrium in stochastic Hamiltonian systems
This paper is concerned with a class of multivariable stochastic Hamiltonian systems whose generalised position is related by an ordinary differential equation to the momentum governed by an Ito stochastic differential equation. The latter is driven by a standard Wiener process and involves both conservative and viscou...
2312.09475v1
2023-12-16
Continuous Phase Transition in Anyonic-PT Symmetric Systems
We reveal the continuous phase transition in anyonic-PT symmetric systems, contrasting with the discontinuous phase transition corresponding to the discrete (anti-) PT symmetry. The continuous phase transition originates from the continuity of anyonic-PT symmetry. We find there are three information-dynamics patterns f...
2312.10350v4
2023-12-20
Quadrature squeezing enhances Wigner negativity in a mechanical Duffing oscillator
Generating macroscopic non-classical quantum states is a long-standing challenge in physics. Anharmonic dynamics is an essential ingredient to generate these states, but for large mechanical systems, the effect of the anharmonicity tends to become negligible compared to decoherence. As a possible solution to this chall...
2312.12986v1
2023-12-21
Subsonic time-periodic solution to damped compressible Euler equations with large entropy
In this paper, one-dimensional nonisentropic compressible Euler equations with linear damping $\alpha(x)\rho u$ are analyzed.~We want to explore the conditions under which a subsonic temporal periodic boundary can trigger a time-periodic $C^{1}$ solution. To achieve this aim, we use a technically constructed iteration ...
2312.13546v1
2023-12-27
Universal orbital and magnetic structures in infinite-layer nickelates
We conducted a comparative study of the rare-earth infinite-layer nickelates films, RNiO2 (R = La, Pr, and Nd) using resonant inelastic X-ray scattering (RIXS). We found that the gross features of the orbital configurations are essentially the same, with minor variations in the detailed hybridization. For low-energy ex...
2312.16444v1
2024-01-05
Response solutions for beam equations with nonlocal nonlinear damping and Liouvillean frequencies
Response solutions are quasi-periodic ones with the same frequency as the forcing term. The present work is devoted to the construction of response solutions for $d$-dimensional beam equations with nonlocal nonlinear damping, which model frictional mechanisms affecting the bodies based on the average. By considering $\...
2401.02628v1
2024-01-10
Stochastic modelling of blob-like plasma filaments in the scrape-off layer: Continuous velocity distributions
A stochastic model for a superposition of uncorrelated pulses with a random distribution of amplitudes, sizes, and velocities is analyzed. The pulses are assumed to move radially with fixed shape and amplitudes decreasing exponentially in time due to linear damping. The pulse velocities are taken to be time-independent...
2401.05198v1
2024-01-11
Optical and acoustic plasmons in the layered material Sr$_2$RuO$_4$
We use momentum-dependent electron energy-loss spectroscopy in transmission to study collective charge excitations in the "strange" layer metal Sr$_2$RuO$_4$. We cover a complete range between in-plane and out-of-plane oscillations. Outside of the classical range of electron-hole excitations, leading to a Landau dampin...
2401.05880v1
2024-01-12
Robust fully discrete error bounds for the Kuznetsov equation in the inviscid limit
The Kuznetsov equation is a classical wave model of acoustics that incorporates quadratic gradient nonlinearities. When its strong damping vanishes, it undergoes a singular behavior change, switching from a parabolic-like to a hyperbolic quasilinear evolution. In this work, we establish for the first time the optimal e...
2401.06492v1
2024-01-12
Semilinear damped wave equations on the Heisenberg group with initial data from Sobolev spaces of negative order
In this paper, we focus on studying the Cauchy problem for semilinear damped wave equations involving the sub-Laplacian $\mathcal{L}$ on the Heisenberg group $\mathbb{H}^n$ with power type nonlinearity $|u|^p$ and initial data taken from Sobolev spaces of negative order homogeneous Sobolev space $\dot H^{-\gamma}_{\mat...
2401.06565v1
2024-01-12
Universal Modelling of Emergent Oscillations in Fractional Quantum Hall Fluids
Density oscillations in quantum fluids can reveal their fundamental characteristic features. In this work, we study the density oscillation of incompressible fractional quantum Hall (FQH) fluids created by flux insertion. For the model Laughlin state, we find that the complex oscillations seen in various density profil...
2401.06856v1
2024-01-19
Quantum circuit model for discrete-time three-state quantum walks on Cayley graphs
We develop qutrit circuit models for discrete-time three-state quantum walks on Cayley graphs corresponding to Dihedral groups $D_N$ and the additive groups of integers modulo any positive integer $N$. The proposed circuits comprise of elementary qutrit gates such as qutrit rotation gates, qutrit-$X$ gates and two-qutr...
2401.11023v1
2024-01-22
Exact Normal Modes of Quantum Plasmas
The normal modes, i.e., the eigen solutions to the dispersion relation equation, are the most fundamental properties of a plasma, which also of key importance to many nonlinear effects such as parametric and two-plasmon decay, and Raman scattering. The real part indicates the intrinsic oscillation frequency while the i...
2401.11894v1
2024-01-23
On the stability and emittance growth of different particle phase-space distributions in a long magnetic quadrupole channel
The behavior of K-V, waterbag, parabolic, conical and Gaussian distributions in periodic quadrupole channels is studied by particle simulations. It is found that all these different distributions exhibit the known K-V instabilities. But the action of the K-V type modes becomes more and more damped in the order of the t...
2401.12595v1
2024-01-26
Double pulse all-optical coherent control of ultrafast spin-reorientation in antiferromagnetic rare-earth orthoferrite
A pair of circularly polarized laser pulses of opposite helicities are shown to control the route of spin reorientation phase transition in rare-earth antiferromagnetic orthoferrite SmTbFeO$_3$. The route can be efficiently controlled by the delay between the pulses and the sample temperature. Simulations employing ear...
2401.15009v1
2024-01-31
Observer-based Controller Design for Oscillation Damping of a Novel Suspended Underactuated Aerial Platform
In this work, we present a novel actuation strategy for a suspended aerial platform. By utilizing an underactuation approach, we demonstrate the successful oscillation damping of the proposed platform, modeled as a spherical double pendulum. A state estimator is designed in order to obtain the deflection angles of the ...
2401.17676v1
2024-02-02
Long-time dynamics of stochastic wave equation with dissipative damping and its full discretization: exponential ergodicity and strong law of large numbers
For stochastic wave equation, when the dissipative damping is a non-globally Lipschitz function of the velocity, there are few results on the long-time dynamics, in particular, the exponential ergodicity and strong law of large numbers, for the equation and its numerical discretization to our knowledge. Focus on this i...
2402.01137v1
2024-02-05
Symmetries and conservation laws of a fifth-order KdV equation with time-dependent coefficients and linear damping
A fifth-order KdV equation with time dependent coefficients and linear damping has been studied. Symmetry groups have several different applications in the context of nonlinear differential equations. For instance, they can be used to determine conservation laws. We obtain the symmetries of the model applying Lie's cla...
2402.03265v1
2024-02-07
Curvature-Informed SGD via General Purpose Lie-Group Preconditioners
We present a novel approach to accelerate stochastic gradient descent (SGD) by utilizing curvature information obtained from Hessian-vector products or finite differences of parameters and gradients, similar to the BFGS algorithm. Our approach involves two preconditioners: a matrix-free preconditioner and a low-rank ap...
2402.04553v1
2024-02-08
A non-damped stabilization algorithm for multibody dynamics
The stability of integrators dealing with high order Differential Algebraic Equations (DAEs) is a major issue. The usual procedures give rise to instabilities that are not predicted by the usual linear analysis, rendering the common checks (developed for ODEs) unusable. The appearance of these difficult-toexplain and u...
2402.05768v1
2024-02-09
Constraints on Quasinormal modes from Black Hole Shadows in regular non-minimal Einstein Yang-Mills Gravity
This work deals with the scalar quasinormal modes using higher order WKB method and black hole shadow in non-minimal Einstein Yang-Mills theory. To validate the results of quasinormal modes, time domain profiles are also investigated. We found that with an increase in the magnetic charge of the black hole, the ring-dow...
2402.06186v1
2024-02-14
The impact of load placement on grid resonances during grid restoration
As inverter-based generation is being massively deployed in the grid, these type of units have to take over the current roles of conventional generation, including the capability of restoring the grid. In this context, the resonances of the grid during the first steps of a black start can be concerning, given that the ...
2402.09294v1
2024-02-19
Gravitational wave asteroseismology of dark matter hadronic stars
The influence of the dark matter mass~($M_{\chi}$) and the Fermi momentum~($k_{F}^{\dm}$) on the $f_0$-mode oscillation frequency, damping time parameter, and tidal deformability of hadronic stars are studied by employing a numerical integration of hydrostatic equilibrium, nonradial oscillation, and tidal deformability...
2402.12600v1
2024-02-21
Landau damping, collisionless limit, and stability threshold for the Vlasov-Poisson equation with nonlinear Fokker-Planck collisions
In this paper, we study the Vlasov-Poisson-Fokker-Planck (VPFP) equation with a small collision frequency $0 < \nu \ll 1$, exploring the interplay between the regularity and size of perturbations in the context of the asymptotic stability of the global Maxwellian. Our main result establishes the Landau damping and enha...
2402.14082v2
2024-02-22
Long-time asymptotics of the damped nonlinear Klein-Gordon equation with a delta potential
We consider the damped nonlinear Klein-Gordon equation with a delta potential \begin{align*} \partial_{t}^2u-\partial_{x}^2u+2\alpha \partial_{t}u+u-\gamma {\delta}_0u-|u|^{p-1}u=0, \ & (t,x) \in \mathbb{R} \times \mathbb{R}, \end{align*} where $p>2$, $\alpha>0,\ \gamma<2$, and $\delta_0=\delta_0 (x)$ denotes the Dirac...
2402.14381v2
2024-02-22
Low-frequency Resonances in Grid-Forming Converters: Causes and Damping Control
Grid-forming voltage-source converter (GFM-VSC) may experience low-frequency resonances, such as synchronous resonance (SR) and sub-synchronous resonance (SSR), in the output power. This paper offers a comprehensive study on the root causes of low-frequency resonances with GFM-VSC systems and the damping control method...
2402.14543v1
2024-02-27
Unified study of viscoelasticity and sound damping in hard and soft amorphous solids
Recent research has made significant progress in understanding the non-phonon vibrational states present in amorphous materials. It has been established that their vibrational density of states follows non-Debye scaling laws. Here, we show that the non-Debye scaling laws play a crucial role in determining material prop...
2402.17335v1
2024-02-29
Quantum coherence and entanglement under the influence of decoherence
In this work, we delve into the dynamic traits of the relative entropy of quantum coherence (REQC) as the quantum system interacts with the different noisy channels, drawing comparisons with entanglement (concurrence). The research results demonstrate the broader prevalence and stronger robustness of the REQC as oppose...
2402.19055v1
2024-03-02
Diffusive Decay of Collective Quantum Excitations in Electron Gas
In this work the multistream quasiparticle model of collective electron excitations is used to study the energy-density distribution of collective quantum excitations in an interacting electron gas with arbitrary degree of degeneracy. Generalized relations for the probability current and energy density distributions is...
2403.01099v1
2024-03-04
Successive quasienergy collapse and the driven Dicke phase transition in the few-emitter limit
The emergent behavior that arises in many-body systems of increasing size follows universal laws that become apparent in order-to-disorder transitions. While this behavior has been traditionally explored for large numbers of emitters, recent progress allows for the exploration of the few-emitter limit, where correlatio...
2403.02417v1
2024-03-05
Domain-Agnostic Mutual Prompting for Unsupervised Domain Adaptation
Conventional Unsupervised Domain Adaptation (UDA) strives to minimize distribution discrepancy between domains, which neglects to harness rich semantics from data and struggles to handle complex domain shifts. A promising technique is to leverage the knowledge of large-scale pre-trained vision-language models for more ...
2403.02899v1
2024-03-12
Spatially oscillating correlation functions in $\left(2+1\right)$-dimensional four-fermion models: The mixing of scalar and vector modes at finite density
In this work, we demonstrate that the mixing of scalar and vector condensates produces spatially oscillating, but exponentially damped correlation functions in fermionic theories at finite density and temperature. We find a regime exhibiting this oscillatory behavior in a Gross-Neveu-type model that also features vecto...
2403.07430v1
2024-03-13
Painlevé Analysis, Prelle-Singer Approach, Symmetries and Integrability of Damped Hénon-Heiles System
We consider a modified damped version of H\'enon-Heiles system and investigate its integrability. By extending the Painlev\'e analysis of ordinary differential equations we find that the modified H\'enon-Heiles system possesses the Painlev\'e property for three distinct parametric restrictions. For each of the identifi...
2403.08410v1
2024-03-15
Delayed interactions in the noisy voter model through the periodic polling mechanism
We investigate the effects of delayed interactions on the stationary distribution of the noisy voter model. We assume that the delayed interactions occur through the periodic polling mechanism and replace the original instantaneous two-agent interactions. In our analysis, we require that the polling period aligns with ...
2403.10277v1
2024-03-16
CETASim: A numerical tool for beam collective effect study in storage rings
We developed a 6D multi-particle tracking program CETASim in C++ programming language to simulate intensity-dependent effects in electron storage rings. The program can simulate the beam collective effects due to short-range/long-range wakefields for single/coupled-bunch instability studies. It also features to simulat...
2403.10973v1
2024-03-18
Mitigation of the Microbunching Instability Through Transverse Landau Damping
The microbunching instability has been a long-standing issue for high-brightness free-electron lasers (FELs), and is a significant show-stopper to achieving full longitudinal coherence in the x-ray regime. This paper reports the first experimental demonstration of microbunching instability mitigation through transverse...
2403.11594v1
2024-03-19
Calculating quasinormal modes of extremal and non-extremal Reissner-Nordström black holes with the continued fraction method
We use the numerical continued fraction method to investigate quasinormal mode spectra of extremal and non-extremal Reissner-Nordstr\"om black holes in the low and intermediate damping regions. In the extremal case, we develop techniques that significantly expand the calculated spectrum from what had previously appeare...
2403.13074v1
2024-03-19
Uniform vorticity depletion and inviscid damping for periodic shear flows in the high Reynolds number regime
We study the dynamics of the two dimensional Navier-Stokes equations linearized around a shear flow on a (non-square) torus which possesses exactly two non-degenerate critical points. We obtain linear inviscid damping and vorticity depletion estimates for the linearized flow that are uniform with respect to the viscosi...
2403.13104v1
2024-03-26
Greybody Factors Imprinted on Black Hole Ringdowns. II. Merging Binary Black Holes
The spectral amplitude of the merger-ringdown gravitational wave (GW) emitted by a comparable mass-ratio black hole merger is modeled by the greybody factor of the remnant black hole. Our model does not include fitting parameters except for a single overall spectral amplitude. We perform the mass-spin inference from th...
2403.17487v1
2024-03-27
Fractional variational integrators based on convolution quadrature
Fractional dissipation is a powerful tool to study non-local physical phenomena such as damping models. The design of geometric, in particular, variational integrators for the numerical simulation of such systems relies on a variational formulation of the model. In [19], a new approach is proposed to deal with dissipat...
2403.18362v1
2024-04-02
High-energy neutrinos flavour composition as a probe of neutrino magnetic moments
Neutrino propagation in the Galactic magnetic field is considered. To describe neutrino flavour and spin oscillations on the galactic scale baselines an approach using wave packets is developed. Evolution equations for the neutrino wave packets in a uniform and non-uniform magnetic field are derived. Analytical express...
2404.02027v1
2018-06-27
Deterministics descriptions of the turbulence in the Navier-Stokes equations
This PhD thesis is devoted to deterministic study of the turbulence in the Navier- Stokes equations. The thesis is divided in four independent chapters.The first chapter involves a rigorous discussion about the energy's dissipation law, proposed by theory of the turbulence K41, in the deterministic setting of the homog...
1806.10430v2
1996-10-28
QSO Absorbing Galaxies at z<~1: Deep Imaging and Spectroscopy in the Field of 3C 336
We present very deep WFPC2 images and FOS spectroscopy from the Hubble Space Telescope (HST) together with numerous supporting ground-based observations of the field of the quasar 3C 336 ($z_{em}=0.927$). The observations are designed to investigate the nature of galaxies producing metal line absorption systems in the ...
9610230v1
1996-11-05
The nature of intermediate-redshift damped Ly-alpha absorbers
We present HST/WFPC2 high-spatial resolution images in the R and B bands of the close environment of the sightlines to seven quasars which spectra show either a damped Ly-alpha absorption line, 21cm absorption, or a very strong MgII/FeII absorption system at intermediate redshifts (0.4 < z < 1). Objects down to about 0...
9611031v1
1997-07-08
The Formation of Galactic Disks
We study the population of galactic disks expected in current hierarchical clustering models for structure formation. A rotationally supported disk with exponential surface density profile is assumed to form with a mass and angular momentum which are fixed fractions of those of its surrounding dark halo. We assume that...
9707093v1
1997-09-26
No C+ emission from the z=3.137 damped Lyman-alpha absorber towards PC1643+4631A
We describe a search for redshifted [C II] in a z=3.137 damped Ly-alpha absorption system that has a large neutral hydrogen column density and which was controversially reported to be a source of CO emission, indicative of rapid star-formation (Frayer, Brown & Vanden Bout 1994; Braine, Downes & Guilloteau 1996). There ...
9709266v1
1998-04-06
Three-dimensional waves generated at Lindblad resonances in thermally stratified disks
We analyze the linear, 3D response to tidal forcing of a disk that is thin and thermally stratified in the direction normal to the disk plane. We model the vertical disk structure locally as a polytrope which represents a disk of high optical depth. We solve the 3D gas-dynamic equations semi-analytically in the neighbo...
9804063v1
2000-11-23
Near-Infrared Integral Field Spectroscopy of Damped Lyman-alpha Systems
We assess the feasibility of detecting star formation in damped Lyman-alpha systems (DLAs) at z>1 through near-infrared spectroscopy using the forthcoming integral field units on 8m-class telescopes. Although their relation to galaxies is not well established, high-z DLAs contain most of the neutral gas in the Universe...
0011421v1
2001-08-07
Dynamics and Origin of the 2:1 Orbital Resonances of the GJ 876 Planets
(Abridged) A dynamical fit has placed the two planets about the star GJ 876 in coplanar orbits deep in 3 resonances at the 2:1 mean-motion commensurability with small libration amplitudes. The libration of both lowest order mean-motion resonance variables, theta_1 and theta_2, and the secular resonance variable, theta_...
0108104v2
2001-12-03
Euler, Jacobi, and Missions to Comets and Asteroids
Whenever a freely spinning body is found in a complex rotational state, this means that either the body is a recent victim of an impact or a tidal interaction, or is a fragment of a recently disrupted progenitor. Another factor (relevant for comets) is outgassing. Due to impacts, tidal forces and outgassing, the astero...
0112054v3
2002-06-17
The UCSD HIRES/KECK I Damped Lya Abundance Database: IV. Probing Galactic Enrichment Histories with Nitrogen
We present 14 N^0 measurements from our HIRES/Keck database of damped Lya abundances. These data are combined with measurements from the recent and past literature to build an homogeneous, uniform set of observations. We examine photoionization diagnostics like Fe^++ and Ar^0 in the majority of the complete sample and ...
0206296v1
2003-08-11
The Nature of Damped Ly-alpha Absorbing Galaxies at z<=1--A Photometric Redshift Survey of Damped Ly-alpha Absorbers
We study the nature of damped Lya absorption (DLA) systems at z<=1 using a sample of 11 DLA galaxies, for which accurate redshift measurements are available. We demonstrate that the precision of photometric redshifts is sufficient for identifying DLA galaxies, because DLAs are rare and their intrinsically high column d...
0308190v1
2004-07-21
Discovery of a Primitive Damped Lyman alpha Absorber Near an X-ray Bright Galaxy Group in the Virgo Cluster
We present a new UV echelle spectrum of PG1216+069, obtained with HST+STIS, which reveals damped Lya (DLA) absorption as well as O I, C II, Si II, and Fe II absorption lines at z(abs) = 0.00632 near the NGC4261 group. The absorber shows no evidence of highly-ionized gas, which places constraints on "warm-hot" missing b...
0407465v2
2004-08-27
Detection of 21 Centimeter HI Absorption at z = 0.78 in a Survey of Radio Continuum Sources
We report the detection of a deep broad HI 21 cm absorption system at z = 0.78 toward the radio source [HB89] 2351+456 (4C+45.51) at z = 1.992. The HI absorption was identified in a blind spectral line survey conducted at the Green Bank Telescope spanning 0.63 < z < 1.10 toward a large sample of radio continuum sources...
0408531v1
2005-03-17
The first WIMPy halos
Dark matter direct and indirect detection signals depend crucially on the dark matter distribution. While the formation of large scale structure is independent of the nature of the cold dark matter (CDM), the fate of inhomogeneities on sub-galactic scales, and hence the present day CDM distribution on these scales, dep...
0503387v2
2005-06-30
Molecular Hydrogen in the Damped Ly alpha Absorber of Q1331+170
We used HST/STIS to obtain the spectrum of molecular hydrogen associated with the damped Ly$\alpha$ system at $z_{\rm abs}=1.7765$ toward the quasar Q1331+170 at $z_{\rm em}=2.084$. Strong ${\rm H}_2$ absorption was detected, with a total ${\rm H}_2$ column density of $N({\rm H}_2)=(4.45\pm 0.36)\times 10^{19} {\rm cm^...
0506766v1
1997-05-06
Resonant Raman Scattering in Antiferromagnets
Two-magnon Raman scattering provides important information about electronic correlations in the insulating parent compounds of high-$T_c$ materials. Recent experiments have shown a strong dependence of the Raman signal in $B_{1g}$ geometry on the frequency of the incoming photon. We present an analytical and numerical ...
9705051v1
1998-09-15
Solid friction at high sliding velocities: an explicit 3D dynamical SPH approach
We present realistic 3D numerical simulations of elastic bodies sliding on top of each other in a regime of velocities ranging from meters to tens of meters per second using the so-called Smoothed Particle Hydrodynamics (SPH) method. Our investigations are restricted to regimes of pressure and roughness where only elas...
9809213v1
2000-03-10
Competing orders and quantum criticality in doped antiferromagnets
We use a number of large-N limits to explore the competition between ground states of square lattice doped antiferromagnets which break electromagnetic U(1), time-reversal, or square lattice space group symmetries. Among the states we find are d-, (s+id)-, and (d+id)-wave superconductors, Wigner crystals, Wigner crysta...
0003163v7
2001-12-03
Theory of proximity effect in superconductor/ferromagnet heterostructures
We present a microscopic theory of proximity effect in the ferromagnet/superconductor/ferromagnet (F/S/F) nanostructures where S is s-wave low-T_c superconductor and F's are layers of 3d transition ferromagnetic metal. Our approach is based on the solution of Gor'kov equations for the normal and anomalous Green's funct...
0112034v3
2007-07-27
C IV absorption in damped and sub-damped Lyman-alpha systems: correlations with metallicity and implications for galactic winds at z~2-3
We present a study of C IV absorption in a sample of 63 damped Lyman-alpha (DLA) systems and 11 sub-DLAs in the redshift range 1.75<z_abs<3.61, using a dataset of high-resolution (6.6 km/s FWHM), high signal-to-noise VLT/UVES spectra. Narrow and broad C IV absorption line components indicate the presence of both warm, ...
0707.4065v2
2007-09-25
On the Structure of Dark Matter Halos at the Damping Scale of the Power Spectrum with and without Relict Velocities
We report a series of high-resolution cosmological N-body simulations designed to explore the formation and properties of dark matter halos with masses close to the damping scale of the primordial power spectrum of density fluctuations. We further investigate the effect that the addition of a random component, v_rms, i...
0709.4027v1
2008-10-01
Corotational Instability of Inertial-Acoustic Modes in Black Hole Accretion Discs and Quasi-Periodic Oscillations
We study the global stability of non-axisymmetric p-modes (also called inertial-acoustic modes) trapped in the inner-most regions of accretion discs around black holes. We show that the lowest-order (highest-frequency) p-modes, with frequencies $\omega=(0.5-0.7) m\Omega_{\rm ISCO}$, can be overstable due to general rel...
0810.0203v2
2008-10-03
Stochastic excitation of nonradial modes II. Are solar asymptotic gravity modes detectable?
Detection of solar gravity modes remains a major challenge to our understanding of the innerparts of the Sun. Their frequencies would enable the derivation of constraints on the core physical properties while their amplitudes can put severe constraints on the properties of the inner convective region. Our purpose is to...
0810.0602v2
2008-10-20
The kinematic signature of damped Lyman alpha systems: Using the D-index to screen for high column density HI absorbers
Using a sample of 21 damped Lyman alpha systems (DLAs) and 35 sub-DLAs, we evaluate the D-index = EW / Delta v x 1000 from high resolution spectra of the MgII lambda 2796 profile. This sample represents an increase in sub-DLA D-index statistics by a factor of four over the sample used by Ellison (2006). We investigate ...
0810.3700v1
2009-01-24
Dynamic migration of rotating neutron stars due to a phase transition instability
Using numerical simulations based on solving the general relativistic hydrodynamic equations, we study the dynamics of a phase transition in the dense core of isolated rotating neutron stars, triggered by the back bending instability reached via angular momentum loss. In particular, we investigate the dynamics of a mig...
0901.3819v2
2009-02-12
New Magellan Inamori Kyocera Echelle Observations of z<1.5 sub-damped Lyman-alpha systems
The Damped and sub-Damped Lyman-alpha (DLA and sub-DLA) systems seen in the spectra of QSOs offer a unique way to study the interstellar medium of high redshift galaxies. In this paper we report on new abundance determinations in a sample of 10 new systems, nine of the lesser studied sub-DLAs and one DLA, along the lin...
0902.2022v2
2009-04-16
Revisiting the origin of the high metallicities of sub-damped Lyman-alpha systems
Sub-damped Lyman-alpha systems (sub-DLAs) have previously been found to exhibit a steeper metallicity evolution than the classical damped Lyman-alpha systems (DLAs), evolving to close to solar metallicity by z~1. From new high-resolution spectra of 17 sub-DLAs we have increased the number of measurements of [Fe/H] at z...
0904.2531v1
2009-05-27
A MIKE + UVES survey of Sub-Damped Lyman-Alpha Systems at z<1.5
We have combined the results from our recent observations of Damped and sub-Damped Lyman-alpha systems with the MIKE and UVES spectrographs on the Magellan Clay and VLT Kueyen telescopes with ones from the literature to determine the N(HI)-weighted mean metallicity of these systems based both on Fe, a depleted element ...
0905.4473v2
2009-11-18
Slow Diffusive Gravitational Instability Before Decoupling
Radiative diffusion damps acoustic modes at large comoving wavenumber (k) before decoupling (``Silk damping''). In a simple WKB analysis, neglecting moments of the temperature distribution beyond the quadrupole, damping appears in the acoustic mode as a term of order ik^2/(taudot) where taudot is the scattering rate pe...
0911.3665v1
2009-12-14
Using 21cm Absorption in Small Impact Parameter Galaxy-QSO Pairs to Probe Low-Redshift Damped and Sub-Damped Lyman-alpha System
To search for low-redshift damped Lyman-alpha (DLA) and sub-DLA quasar absorbers, we have conducted a 21cm absorption survey of radio-loud quasars at small impact parameters to foreground galaxies selected from the Sloan Digital Sky Survey (SDSS). Here we present the first results from this survey based on observations...
0912.2575v2
2010-04-02
Modeling the Time Variability of SDSS Stripe 82 Quasars as a Damped Random Walk
We model the time variability of ~9,000 spectroscopically confirmed quasars in SDSS Stripe 82 as a damped random walk. Using 2.7 million photometric measurements collected over 10 years, we confirm the results of Kelly et al. (2009) and Koz{\l}owski et al. (2010) that this model can explain quasar light curves at an im...
1004.0276v2
2010-04-21
Kadanoff-Baym description of Hubbard clusters out of equilibrium: performance of many-body schemes, correlation-induced damping and multiple steady states
We present in detail a method we recently introduced (PRL. 103, 176404 (2009)) to describe finite systems in and out of equilibrium, where the evolution in time is performed via the Kadanoff-Baym Equations (KBE) within Many-Body Perturbation Theory (MBPT). The main property we analyze is the time-dependent density. We ...
1004.3662v1