publicationDate
stringlengths
1
2.79k
title
stringlengths
1
36.5k
abstract
stringlengths
1
37.3k
id
stringlengths
9
47
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
2023-10-20
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
2023-10-22
The residual flow in well-optimized stellarators
The gyrokinetic theory of the residual flow, in the electrostatic limit, is revisited, with optimized stellarators in mind. We consider general initial conditions for the problem, and identify cases that lead to a non-zonal residual electrostatic potential, i.e. one having a significant component that varies within a f...
2310.14218v2
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
2023-12-16
Spin-torque nano-oscillator based on two in-plane magnetized synthetic ferrimagnets
We report the dynamic characterization of the spin-torque-driven in-plane precession modes of a spin-torque nano-oscillator based on two different synthetic ferrimagnets: a pinned one characterized by a strong RKKY interaction which is exchange coupled to an antiferromagnetic layer; and a second one, non-pinned charact...
2312.10451v2
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...
2401.06565v2
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...
2401.12595v2
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
2024-03-02
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
2024-04-09
Calculation of toroidal Alfvén eigenmode mode structure in general axisymmetric toroidal geometry
A workflow is developed based on the ideal MHD model to investigate the linear physics of various Alfv\'en eigenmodes in general axisymmetric toroidal geometry, by solving the coupled shear Alfv\'en wave (SAW) and ion sound wave (ISW) equations in ballooning space. The model equations are solved by the FALCON code in t...
2404.06296v1
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
2019-03-04
Constant angle surfaces in 4-dimensional Minkowski space
We first define a complex angle between two oriented spacelike planes in 4-dimensional Minkowski space, and then study the constant angle surfaces in that space, i.e. the oriented spacelike surfaces whose tangent planes form a constant complex angle with respect to a fixed spacelike plane. This notion is the natural Lo...
1903.01554v1
2020-05-17
Universal constants and natural systems of units in a spacetime of arbitrary dimension
We study the properties of fundamental physical constants using the threefold classification of dimensional constants proposed by J.-M. L{\'e}vy-Leblond: constants of objects (masses, etc.), constants of phenomena (coupling constants), and "universal constants" (such as $c$ and $\hbar$). We show that all of the known "...
2005.08196v3
2020-11-13
Losing the trace to find dynamical Newton or Planck constants
We show that promoting the trace part of the Einstein equations to a trivial identity results in the Newton constant being an integration constant. Thus, in this formulation the Newton constant is a global dynamical degree of freedom which is also a subject to quantization and quantum fluctuations. This is similar to w...
2011.07055v2
2008-11-24
Artificial contradiction between cosmology and particle physics: the lambda problem
It is shown that the usual choice of units obtained by taking G = c = Planck constant = 1, giving the Planck units of mass, length and time, introduces an artificial contradiction between cosmology and particle physics: the lambda problem that we associate with Planck constant. We note that the choice of Planck constan...
0811.3933v2
2003-02-07
Lattice constant in diluted magnetic semiconductors (Ga,Mn)As
We use the density-functional calculations to investigate the compositional dependence of the lattice constant of (Ga,Mn)As containing various native defects. The lattice constant of perfect mixed crystals does not depend much on the concentration of Mn. The lattice parameter increases if some Mn atoms occupy interstit...
0302150v1
2002-12-04
Implications of a Time-Varying Fine Structure Constant
Much work has been done after the possibility of a fine structure constant being time-varying. It has been taken as an indication of a time-varying speed of light. Here we prove that this is not the case. We prove that the speed of light may or may not vary with time, independently of the fine structure constant being ...
0212020v1
2005-12-20
Local Experiments See Cosmologically Varying Constants
We describe a rigorous construction, using matched asymptotic expansions, which establishes under very general conditions that local terrestrial and solar-system experiments will measure the effects of varying `constants' of Nature occurring on cosmological scales to computable precision. In particular, `constants' dri...
0512117v2
1992-12-22
The Third Electromagnetic Constant of an Isotropic Medium:
In addition to the dielectric and magnetic permeability constants, another constant is generally needed to describe the electrodynamic properties of a linear isotropic medium. We discuss why the need for the third constant arises and what sort of physical situations can give rise to a non-zero value for it. This additi...
9212300v2
2001-09-15
Two-dimensional Finsler metrics of constant curvature
A Riemannian metric is of constant curvature if and only if it is locally projectively flat. There are infinitely many locally projectively flat Finsler metrics of constant curvature, that are special solutions to the Hilbert's Fourth Problem. In this paper, we use the technique in the paper titled "Finsler metrics w...
0109097v1
2002-09-04
Experimental Consequences of Time Variations of the Fundamental Constants
We discuss the experimental consequences of hypothetical time variations of the fundamental constants. We emphasize that from a purely phenomenological point of view, only dimensionless fundamental constants have significance. Two classes of experiments are identified that give results that are essentially independent ...
0209016v1
2008-10-13
A note on Artin's constant
We suggest a new approach to Artin's constant that leads to its representation as an infinite sum divided by another infinite sum. The same approach works well for Stephens' constant and higher rank Artin's constants. The main results are theoretical but there are interesting experimental and computational aspects.
0810.2325v4
2009-03-27
Effect of non-zero constant vorticity on the nonlinear resonances of capillary water waves
The influence of an underlying current on 3-wave interactions of capillary water waves is studied. The fact that in irrotational flow resonant 3-wave interactions are not possible can be invalidated by the presence of an underlying current of constant non-zero vorticity. We show that: 1) wave trains in flows with const...
0903.4813v1
2010-04-09
A New Construction for Constant Weight Codes
A new construction for constant weight codes is presented. The codes are constructed from $k$-dimensional subspaces of the vector space $\F_q^n$. These subspaces form a constant dimension code in the Grassmannian space $\cG_q(n,k)$. Some of the constructed codes are optimal constant weight codes with parameters not kno...
1004.1503v3
2011-07-01
Mimicking the cosmological constant: constant curvature spherical solutions in a non-minimally coupled model
The purpose of this study is to describe a perfect fluid matter distribution that leads to a constant curvature region, thanks to the effect of a non-minimal coupling. This distribution exhibits a density profile within the range found in the interstellar medium and an adequate matching of the metric components at its ...
1107.0225v1
2013-11-09
On Maxwell's and Poincare's Constants
We prove that for bounded and convex domains in three dimensions, the Maxwell constants are bounded from below and above by Friedrichs' and Poincar\'e's constants. In other words, the second Maxwell eigenvalues lie between the square roots of the second Neumann-Laplace and the first Dirichlet-Laplace eigenvalue.
1311.2186v4
2015-01-08
On the optimal constants in Korn's and geometric rigidity estimates, in bounded and unbounded domains, under Neumann boundary conditions
We are concerned with the optimal constants: in the Korn inequality under tangential boundary conditions on bounded sets $\Omega \subset \mathbb{R}^n$, and in the geometric rigidity estimate on the whole $\mathbb{R}^2$. We prove that the latter constant equals $\sqrt{2}$, and we discuss the relation of the former const...
1501.01917v1
2016-05-16
A Constant-Factor Bi-Criteria Approximation Guarantee for $k$-means++
This paper studies the $k$-means++ algorithm for clustering as well as the class of $D^\ell$ sampling algorithms to which $k$-means++ belongs. It is shown that for any constant factor $\beta > 1$, selecting $\beta k$ cluster centers by $D^\ell$ sampling yields a constant-factor approximation to the optimal clustering w...
1605.04986v1
2016-11-01
Existence of conformal metrics with constant scalar curvature and constant boundary mean curvature on compact manifolds
We study the problem of deforming a Riemannian metric to a conformal one with nonzero constant scalar curvature and nonzero constant boundary mean curvature on a compact manifold of dimension $n\geq 3$. We prove the existence of such conformal metrics in the cases of $n=6,7$ or the manifold is spin and some other remai...
1611.00229v2
2019-05-31
Hyperbolicity constants for pants and relative pants graphs
The pants graph has proved to be influential in understanding 3-manifolds concretely. This stems from a quasi-isometry between the pants graph and the Teichm\"uller space with the Weil-Petersson metric. Currently, all estimates on the quasi-isometry constants are dependent on the surface in an undiscovered way. This pa...
1905.13595v1
2019-11-28
Constant mean curvature Isometric Immersions into $\mathbb{S}^2 \times \mathbb{R}$ and $\mathbb{H}^2 \times \mathbb{R}$ and related results
In this article, we study constant mean curvature isometric immersions into $\mathbb{S}^2 \times \mathbb{R}$ and $\mathbb{H}^2 \times \mathbb{R}$ and we classify these isometric immersions when the surface has constant intrinsic curvature. As applications, we use the sister surface correspondence to classify the consta...
1911.12630v1
2020-12-21
A Couple of Transcendental Prime-Representing Constants
It is well known that the arithmetic nature of Mills' prime-representing constant is uncertain: we do not know if Mills' constant is a rational or irrational number. In the case of other prime-representing constants, irrationality can be proved, but it is not known whether these constants are algebraic or transcendenta...
2012.11750v2
2021-03-17
Complex nilmanifolds with constant holomorphic sectional curvature
A well known conjecture in complex geometry states that a compact Hermitian manifold with constant holomorphic sectional curvature must be K\"ahler if the constant is non-zero and must be Chern flat if the constant is zero. The conjecture is confirmed in complex dimension $2$, by the work of Balas-Gauduchon in 1985 (wh...
2103.09571v1
2021-03-25
Universal Constants as Manifestations of Relativity
We study the possible interpretation of the "universal constants" by the classification of J.~M.~L\'evy-Leblond. $\hbar$ and $c$ are the most common example of constants of this type. Using Fock's principle of the relativity w.r.t. observation means, we show that both $c$ and $\hbar$ can be viewed as manifestations of ...
2103.13854v2
2022-03-30
Convex bodies of constant width in spaces of constant curvature and the extremal area of Reuleaux triangles
Extending Blaschke and Lebesgue's classical result in the Euclidean plane, it has been recently proved in spherical and the hyperbolic cases, as well, that Reuleaux triangles have the minimal area among convex domains of constant width $D$. We prove an essentially optimal stability version of this statement in each of ...
2203.16636v1
2022-05-23
On Computing Coercivity Constants in Linear Variational Problems Through Eigenvalue Analysis
In this work, we investigate the convergence of numerical approximations to coercivity constants of variational problems. These constants are essential components of rigorous error bounds for reduced-order modeling; extension of these bounds to the error with respect to exact solutions requires an understanding of conv...
2205.11580v1
2022-08-07
Spacelike Curves of Constant-Ratio in Pseudo-Galilean Space
In the theory of differential geometry curves, a curve is said to be of constant-ratio if the ratio of the length of the tangential and normal components of its position vector function is constant. In this paper, we study and characterize a spacelike admissible curve of constant-ratio in terms of its curvature functio...
2208.03686v1
2022-08-24
New Geometric Constant Related to the P-angle Function in Banach Spaces
In this paper, combined with the P-angle function of Banach spaces and the geometric constants that can characterize Hilbert spaces, the new angular geometric constant is defined. Firstly, this paper explores the basic properties of the new constant and obtains some inequalities with significant geometric constants. Th...
2208.11239v1
2022-09-22
Kemeny's constant and Wiener index on trees
On trees of fixed order, we show a direct relation between Kemeny's constant and Wiener index, and provide a new formula of Kemeny's constant from the relation with a combinatorial interpretation. Moreover, the relation simplifies proofs of several known results for extremal trees in terms of Kemeny's constant for rand...
2209.11271v1
2023-12-18
Asymptotic products of binomial and multinomial coefficients revisited
In this note, we consider asymptotic products of binomial and multinomial coefficients and determine their asymptotic constants and formulas. Among them, special cases are the central binomial coefficients, the related Catalan numbers, and binomial coefficients in a row of Pascal's triangle. For the latter case, we sho...
2312.11369v1
2023-12-23
The Table of the Structure Constants for the Complex Simple Lie Algebra of Type G_2 and Chevalley Commutator Formulas in the Chevalley Group of Type G_2 over a Field
This article is the second in the series and is devoted to the type G_2. The work consists of two parts. In the first part we calculate the structure constants of the complex simple Lie algebra of type G_2. All structure constants are represented as functions of the structure constants corresponding to extraspecial pai...
2312.15226v1
2003-10-21
Cosmological model with $Ω_M$-dependent cosmological constant
The idea here is to set the cosmical constant $\lambda$ proportional to the scalar of the stress-energy tensor of the ordinary matter. We investigate the evolution of the scale factor in a cosmological model in which the cosmological constant is proportional to the scalar of the stress-energy tensor.
0310609v1