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2017-11-30
TeV dark matter and the DAMPE electron excess
The recent high energy electron and positron flux observed by the DAMPE experiment indicates possible excess events near 1.4 TeV. Such an excess may be evidence of dark matter annihilations or decays in a dark matter subhalo that is located close to the solar system. We give here an analysis of this excess from annihil...
1711.11579v1
2017-12-04
Quasi-degenerate dark matter for DAMPE excess and $3.5\,\textrm{keV}$ line
We propose a quasi-degenerate dark matter scenario to simultaneously explain the $1.4\,\textrm{TeV}$ peak in the high-energy cosmic-ray electron-positron spectrum reported by the DAMPE collaboration very recently and the $3.5\,\textrm{keV}$ X-ray line observed in galaxies clusters and from the Galactic centre and confi...
1712.00922v1
2017-12-06
Collective modes of an imbalanced unitary Fermi gas
We study theoretically the collective mode spectrum of a strongly imbalanced two-component unitary Fermi gas in a cigar-shaped trap, where the minority species forms a gas of polarons. We describe the collective breathing mode of the gas in terms of the Fermi liquid kinetic equation taking collisions into account using...
1712.02181v1
2017-12-07
Bias of Damped Lyman-$α$ systems from their cross-correlation with CMB lensing
We cross-correlate the positions of damped Lyman-$\alpha$ systems (DLAs) and their parent quasar catalog with a convergence map derived from the Planck cosmic microwave background (CMB) temperature data. We make consistent measurements of the lensing signal of both samples in both Fourier and configuration space. By in...
1712.02738v2
2017-12-08
Viscoelastic optical nonlocality of low-loss epsilon-near-zero nanofilms
Optical nonlocalities are elusive and hardly observable in traditional plasmonic materials like noble and alkali metals. Here we report experimental observation of viscoelastic nonlocalities in the infrared optical response of doped cadmium-oxide, epsilon-near-zero nanofilms. The nonlocality is detectable thanks to the...
1712.03169v2
2017-12-08
A Strong Test of the Dark Matter Origin of the 1.4 TeV DAMPE Signal Using IceCube Neutrinos
A tentative excess in the electron spectrum at 1.4 TeV was recently reported by the DArk Matter Particle Explorer (DAMPE). A non-astrophysical scenario in which dark matter particles annihilate or decay in a local clump has been invoked to explain the excess. If $e^\pm$ annihilation channels in the final states are med...
1712.03210v2
2017-12-11
Prospects of type-II seesaw at future colliders in light of the DAMPE $e^+ e^-$ excess
The DAMPE $e^+ e^-$ excess at around 1.4 TeV could be explained in the type-II seesaw model with a scalar dark mater $D$ which is stabilized by a discrete $Z_2$ symmetry. The simplest scenario is the annihilation $DD \to H^{++} H^{--}$ followed by the subsequent decay $H^{\pm\pm} \to e^\pm e^\pm$, with both the DM and ...
1712.03642v3
2017-12-12
Thermal decoherence in a strongly correlated Bose liquid
We compute the single particle spectral function of a Bose liquid on a lattice, at integer filling, close to the superfluid-Mott transition. We use a `static path approximation' that retains all the classical thermal fluctuations in the problem, and a real space implementation of the random phase approximation (RPA) fo...
1712.04433v1
2017-12-17
Oscillation energy based sensitivity analysis and control for multi-mode oscillation systems
This paper describes a novel approach to analyze and control systems with multi-mode oscillation problems. Traditional single dominant mode analysis fails to provide effective control actions when several modes have similar low damping ratios. This work addresses this problem by considering all modes in the formulation...
1712.06157v1
2017-12-19
Nonequilibrium quantum solvation with a time-dependent Onsager cavity
We formulate a theory of nonequilibrium quantum solvation in which parameters of the solvent are explicitly depending on time. We assume in a simplest approach a spherical molecular Onsager cavity with a time-dependent radius. We analyze the relaxation properties of a test molecular point dipole in a dielectric solvent...
1712.06973v2
2017-12-26
Newton's equation of motion with quadratic drag force and Toda's potential as a solvable one
The family of exactly solvable potentials for Newton's equation of motion in the one-dimensional system with quadratic drag force has been determined completely. The determination is based on the implicit inverse-function solution valid for any potential shape, and hence exhaustive. This solvable family includes the ex...
1712.09189v4
2017-12-23
Density Fluctuations in the Solar Wind Driven by Alfvén Wave Parametric Decay
Measurements and simulations of inertial compressive turbulence in the solar wind are characterized by anti-correlated magnetic fluctuations parallel to the mean field and density structures. This signature has been interpreted as observational evidence for non-propagating pressure balanced structures (PBS), kinetic io...
1712.09336v2
2018-01-15
A radiative neutrino mass model in light of DAMPE excess with hidden gauged $U(1)$ symmetry
We propose a one-loop induced neutrino mass model with hidden $U(1)$ gauge symmetry, in which we successfully involve a bosonic dark matter (DM) candidate propagating inside a loop diagram in neutrino mass generation to explain the $e^+e^-$ excess recently reported by the DArk Matter Particle Explorer (DAMPE) experimen...
1801.04729v2
2018-01-22
A port-Hamiltonian approach to the control of nonholonomic systems
In this paper a method of controlling nonholonomic systems within the port-Hamiltonian (pH) framework is presented. It is well known that nonholonomic systems can be represented as pH systems without Lagrange multipliers by considering a reduced momentum space. Here, we revisit the modelling of these systems for the pu...
1801.06954v1
2018-01-23
Temperature gradient driven heat flux closure in fluid simulations of collisionless reconnection
Recent efforts to include kinetic effects in fluid simulations of plasmas have been very promising. Concerning collisionless magnetic reconnection, it has been found before that damping of the pressure tensor to isotropy leads to good agreement with kinetic runs in certain scenarios. An accurate representation of kinet...
1801.07628v1
2018-01-29
Oscillatory relaxation of zonal flows in a multi-species stellarator plasma
The low frequency oscillatory relaxation of zonal potential perturbations is studied numerically in the TJ-II stellarator (where it was experimentally detected for the first time). It is studied in full global gyrokinetic simulations of multi-species plasmas. The oscillation frequency obtained is compared with predicti...
1801.09495v1
2018-01-30
Input / Output Stability of a Damped String Equation coupled with Ordinary Differential System
The input/output stability of an interconnected system composed of an ordinary differential equation and a damped string equation is studied. Issued from the literature on time-delay systems, an exact stability result is firstly derived using pole locations. Then, based on the Small-Gain theorem and on the Quadratic Se...
1801.09916v2
2018-02-05
Intrinsic spin-orbit torque arising from Berry curvature in metallic-magnet/Cu-oxide interface
We report the observation of the intrinsic damping-like spin-orbit torque (SOT) arising from the Berry curvature in metallic-magnet/CuO$_x$ heterostructures. We show that a robust damping-like SOT, an order of magnitude larger than a field-like SOT, is generated in the heterostructure despite the absence of the bulk sp...
1802.01285v2
2018-02-12
Selective Phonon Damping in Topological Semimetals
Topological semimetals are characterized by their intriguing Fermi surfaces (FSs) such as Weyl and Dirac points, or nodal FS, and their associated surface states. Among them, topological crystalline semimetals, in the presence of strong spin-orbit coupling, possess a nodal FS protected by non-symmorphic lattice symmetr...
1802.04300v2
2018-02-14
Motion of interfaces for a damped hyperbolic Allen-Cahn equation
Consider the Allen-Cahn equation $u_t=\varepsilon^2\Delta u-F'(u)$, where $F$ is a double well potential with wells of equal depth, located at $\pm1$. There are a lot of papers devoted to the study of the limiting behavior of the solutions as the diffusion coefficient $\varepsilon\to0^+$, and it is well known that, if ...
1802.05038v1
2018-02-23
Blow up of solutions for semilinear wave equations with noneffective damping
In this paper, we study the finite-time blow up of solutions to the following semilinear wave equation with time-dependent damping \[ \partial_t^2u-\Delta u+\frac{\mu}{1+t}\partial_tu=|u|^p \] in $\mathbb{R}_{+}\times\mathbb{R}^n$. More precisely, for $0\leq\mu\leq 2,\mu \neq1$ and $n\geq 2$, there is no global solutio...
1802.08403v2
2018-03-06
A comparison of semi-Lagrangian discontinuous Galerkin and spline based Vlasov solvers in four dimensions
The purpose of the present paper is to compare two semi-Lagrangian methods in the context of the four-dimensional Vlasov--Poisson equation. More specifically, our goal is to compare the performance of the more recently developed semi-Lagrangian discontinuous Galerkin scheme with the de facto standard in Eulerian Vlasov...
1803.02143v1
2018-03-06
Kak's three-stage protocol of secure quantum communication revisited: Hitherto unknown strengths and weaknesses of the protocol
Kak's three-stage protocol for quantum key distribution is revisited with special focus on its hitherto unknown strengths and weaknesses. It is shown that this protocol can be used for secure direct quantum communication. Further, the implementability of this protocol in the realistic situation is analyzed by consideri...
1803.02157v1
2018-03-09
Dynamical evolutions in non-Hermitian triple-well system with complex potential
We investigate the dynamical properties for non-Hermitian triple-well system with a loss in the middle well. When chemical potentials in two end wells are uniform and nonlinear interactions are neglected, there always exists a dark state, whose eigenenergy becomes zero, and the projections onto which do not change over...
1803.03360v1
2018-03-11
Graph Laplacian Spectrum and Primary Frequency Regulation
We present a framework based on spectral graph theory that captures the interplay among network topology, system inertia, and generator and load damping in determining the overall grid behavior and performance. Specifically, we show that the impact of network topology on a power system can be quantified through the net...
1803.03905v3
2018-03-15
Control Inversion: A Clustering-Based Method for Distributed Wide-Area Control of Power Systems
Wide-area control (WAC) has been shown to be an effective tool for damping low-frequency oscillations in power systems. In the current state of art, WAC is challenged by two main factors - namely, scalability of design and complexity of implementation. In this paper we present a control design called control inversion ...
1803.05947v1
2018-03-18
Damped Anderson acceleration with restarts and monotonicity control for accelerating EM and EM-like algorithms
The expectation-maximization (EM) algorithm is a well-known iterative method for computing maximum likelihood estimates from incomplete data. Despite its numerous advantages, a main drawback of the EM algorithm is its frequently observed slow convergence which often hinders the application of EM algorithms in high-dime...
1803.06673v2
2018-03-21
Connectivity-Preserving Coordination Control of Multi-Agent Systems with Time-Varying Delays
This paper presents a distributed position synchronization strategy that also preserves the initial communication links for single-integrator multi-agent systems with time-varying delays. The strategy employs a coordinating proportional control derived from a specific type of potential energy, augmented with damping in...
1803.08152v1
2018-03-23
A Novel Approach to Resonant Absorption of the Fast MHD Eigenmodes of a Coronal Arcade
The arched field lines forming coronal arcades are often observed to undulate as magnetohydrodynamic (MHD) waves propagate both across and along the magnetic field. These waves are most likely a combination of resonantly coupled fast magnetoacoustic waves and Alfv\'en waves. The coupling results in resonant absorption ...
1803.08948v1
2018-03-25
Parareal exponential $θ$-scheme for longtime simulation of stochastic Schrödinger equations with weak damping
A parareal algorithm based on an exponential $\theta$-scheme is proposed for the stochastic Schr\"odinger equation with weak damping and additive noise. It proceeds as a two-level temporal parallelizable integrator with the exponential $\theta$-scheme as the propagator on the coarse grid. The proposed algorithm in the ...
1803.09188v1
2018-04-01
Aggregated Momentum: Stability Through Passive Damping
Momentum is a simple and widely used trick which allows gradient-based optimizers to pick up speed along low curvature directions. Its performance depends crucially on a damping coefficient $\beta$. Large $\beta$ values can potentially deliver much larger speedups, but are prone to oscillations and instability; hence o...
1804.00325v3
2018-04-03
Damped perturbations in the no-boundary state
We evaluate the no-boundary path integral exactly in a Bianchi IX minisuperspace with two scale factors. In this model the no-boundary proposal can be implemented by requiring one scale factor to be zero initially together with a judiciously chosen regularity condition on the momentum conjugate to the second scale fact...
1804.01102v2
2018-04-04
Stabilizable Gaussian states
The unavoidable interaction of quantum systems with their environment usually results in the loss of desired quantum resources. Suitably chosen system Hamiltonians, however, can, to some extent, counteract such detrimental decay, giving rise to the set of stabilizable states. Here, we discuss the possibility to stabili...
1804.01315v2
2018-04-11
Collisionless sound in a uniform two-dimensional Bose gas
Using linear response theory within the Random Phase Approximation, we investigate the propagation of sound in a uniform two dimensional (2D) Bose gas in the collisionless regime. We show that the sudden removal of a static density perturbation produces a damped oscillatory behavior revealing that sound can propagate a...
1804.04032v2
2018-04-11
Sound propagation in a uniform superfluid two-dimensional Bose gas
In superfluid systems several sound modes can be excited, as for example first and second sound in liquid helium. Here, we excite propagating and standing waves in a uniform two-dimensional Bose gas and we characterize the propagation of sound in both the superfluid and normal regime. In the superfluid phase, the measu...
1804.04037v1
2018-04-14
Theory of plasmon reflection by a 1D junction
We present a comprehensive study of the reflection of normally incident plasmon waves from a low-conductivity 1D junction in a 2D conductive sheet. Rigorous analytical results are derived in the limits of wide and narrow junctions. Two types of phenomena determine the reflectance, the cavity resonances within the junct...
1804.05256v1
2018-03-25
Nonlinear effect of forced harmonic oscillator subject to sliding friction and simulation by a simple nonlinear circuit
We study the nonlinear behaviors of mass-spring systems damped by dry friction using simulation by a nonlinear LC circuit damped by anti-parallel diodes. We show that the differential equation for the electric oscillator is equivalent to the mechanical one's when a piecewise linear model is used to simplify the diodes ...
1804.05762v1
2018-04-17
Asymmetric fitting function for condensed-phase Raman spectroscopy
Asymmetric lineshapes are experimentally observed in Raman spectra of different classes of condensed matter. Determination of the peak parameters, typically done with symmetric pseudo-Voigt functions, in such situations yields unreliable results. While wide choice of asymmetric fitting functions is possible, for the fu...
1804.06083v2
2018-04-23
Linear inviscid damping and enhanced viscous dissipation of shear flows by using the conjugate operator method
We study the large time behavior of solutions to two-dimensional Euler and Navier-Stokes equations linearized about shear flows of the mixing layer type in the unbounded channel $\mathbb{T} \times \mathbb{R}$. Under a simple spectral stability assumption on a self-adjoint operator, we prove a local form of the linear i...
1804.08291v1
2018-04-23
Capillary waves with surface viscosity
Experiments over the last 50 years have suggested a tentative correlation between the surface (shear) viscosity and the stability of a foam or emulsion. We examine this link theoretically using small-amplitude capillary waves in the presence of a surfactant solution of dilute concentrations where the associated Marango...
1804.08389v1
2018-04-23
The Multidimensional Damped Wave Equation: Maximal Weak Solutions for Nonlinear Forcing via Semigroups and Approximation
The damped nonlinear wave equation, also known as the nonlinear telegraph equation, is studied within the framework of semigroups and eigenfunction approximation. The linear semigroup assumes a central role: it is bounded on the domain of its generator for all time t > 0. This permits eigenfunction approximation within...
1804.08394v3
2018-04-24
Bidirectional Controlled Quantum Teleportation Using Eight-Qubit Quantum Channel in Noisy Environments
In this work, a novel protocol is proposed for bidirectional controlled quantum teleportation (BCQT) in which a quantum channel is used with the eight-qubit entangled state. Using the protocol, two users can teleport an arbitrary entangled state and a pure two-qubit state (QBS) to each other simultaneously under the pe...
1804.08876v3
2018-04-25
Type II Seesaw with scalar dark matter in light of AMS-02, DAMPE and Fermi-LAT
The Standard Model (SM) supplemented by Type II Seesaw and a SM gauge-singlet scalar dark matter (DM) is a very simple framework to incorporate the observed neutrino oscillations and provide a plausible DM candidate. In this framework, the scalar DM naturally has a leptophilic nature with a pair annihilating mainly int...
1804.09835v1
2018-05-17
Viscous damping of gravity-capillary waves: Dispersion relations and nonlinear corrections
We discuss the impact of viscosity on nonlinear propagation of surface waves at the interface of air and a fluid of large depth. After a survey of the available approximations of the dispersion relation, we propose to modify the hydrodynamic boundary conditions to model both short and long waves. From them, we derive a...
1805.06777v2
2018-05-25
Calculating the transport properties of magnetic materials from first-principles including thermal and alloy disorder, non-collinearity and spin-orbit coupling
A density functional theory based two-terminal scattering formalism that includes spin-orbit coupling and spin non-collinearity is described. An implementation using tight-binding muffin-tin orbitals combined with extensive use of sparse matrix techniques allows a wide variety of inhomogeneous structures to be flexibly...
1805.10062v1
2018-05-28
The linearized Vlasov and Vlasov-Fokker-Planck equations in a uniform magnetic field
We study the linearized Vlasov equations and the linearized Vlasov-Fokker-Planck equations in the weakly collisional limit in a uniform magnetic field. In both cases, we consider periodic confinement and Maxwellian (or close to Maxwellian) backgrounds. In the collisionless case, for modes transverse to the magnetic fie...
1805.10756v1
2018-06-08
Can Star Products be Augmented by Classical Physics?
It has been suggested that star products in phase-space quantization may be augmented to describe additional, classical effects. That proposal is examined critically here. Two known star products that introduce classical effects are: the generalized Husimi product of coarse-grained quantization, and a non-Hermitian dam...
1806.03309v2
2018-06-20
Large-Scale Demonstration of Precise Demand Response Provided by Residential Heating Systems
Being able to adjust the demand of electricity can be an effective means for power system operators to compensate fluctuating renewable generation, to avoid grid congestion, and to cope with other contingencies. Electric heating and cooling systems of buildings can provide different demand response services because the...
1806.07670v1
2018-06-22
Weakly coupled systems of semi-linear elastic waves with different damping mechanisms in 3D
We consider the following Cauchy problem for weakly coupled systems of semi-linear damped elastic waves with a power source non-linearity in three-dimensions: \begin{equation*} U_{tt}-a^2\Delta U-\big(b^2-a^2\big)\nabla\text{div } U+(-\Delta)^{\theta}U_t=F(U),\,\, (t,x)\in[0,\infty)\times\mathbb{R}^3, \end{equation*}...
1806.08543v2
2018-07-02
Global Existence of Solutions to the Compressible Euler Equations with Time-dependent Damping and Logarithmic State Equation
In mathematical physics, the pressure function is determined by the equation of state. There are two existing barotropic state equations: the state equation for polytropic gas with adiabatic index greater than or equal to 1 and the state equation for generalized Chaplygin gas in cosmology. In this paper, a logarithmic ...
1807.00550v2
2018-07-02
On wave equations of the $p$-Laplacian type with supercritical nonlinearities
This article focuses on a quasilinear wave equation of $p$-Laplacian type: \[ u_{tt} - \Delta_p u -\Delta u_t = f(u) \] in a bounded domain $\Omega \subset \mathbb{R}^3$ with a sufficiently smooth boundary $\Gamma=\partial \Omega$ subject to a generalized Robin boundary condition featuring boundary damping and a nonlin...
1807.00650v1
2018-06-30
Efficient $p$-multigrid method based on an exponential time discretization for compressible steady flows
An efficient multigrid framework is developed for the time marching of steady-state compressible flows with a spatially high-order ($p$-order polynomial) modal discontinuous Galerkin method. The core algorithm that based on a global coupling, exponential time integration scheme provides strong damping effects to accele...
1807.01151v1
2018-07-04
Structural crossover in a model fluid exhibiting two length scales: repercussions for quasicrystal formation
We investigate the liquid state structure of the two-dimensional (2D) model introduced by Barkan et al. [Phys. Rev. Lett. 113, 098304 (2014)], which exhibits quasicrystalline and other unusual solid phases, focussing on the radial distribution function $g(r)$ and its asymptotic decay $r\to\infty$. For this particular m...
1807.01467v1
2018-07-04
Dirac's Method for the Two-Dimensional Damped Harmonic Oscillator in the Extended Phase Space
The system of two-dimensional damped harmonic oscillator is revisited in the extended phase space. It is an old problem already addressed by many authors that we present here in some fresh points of view and carry on smoothly a whole discussion. We show that the system is singular. The classical Hamiltonian is proporti...
1807.01539v2
2018-07-05
Decay of approximate solutions for the damped semilinear wave equation on a bounded 1d domain
In this paper we study the long time behavior for a semilinear wave equation with space-dependent and nonlinear damping term. After rewriting the equation as a first order system, we define a class of approximate solutions that employ tipical tools of hyperbolic systems of conservation laws, such as the Riemann problem...
1807.01968v3
2018-07-07
Axial Quasi-Normal Modes of Scalarized Neutron Stars with Realistic Equations of State
We compute the axial quasi-normal modes of static neutron stars in scalar tensor theory. In particular, we employ various realistic equations of state including nuclear, hyperonic and hybrid matter. We investigate the fundamental curvature mode and compare the results with those of General Relativity. We find that the ...
1807.02598v1
2018-07-09
DLA and sub-DLA metallicity evolution: A case study of absorbers towards Q0338-0005
The damped and sub-damped Lyman alpha systems (DLAs and sub-DLAs) traced in absorption against bright background quasars represent the main reserve of neutral hydrogen at high redshifts. We used the archival Very Large Telescope (VLT) instrument Ultraviolet and Visual Echelle Spectrograph (UVES) high-resolution data of...
1807.04189v1
2018-07-15
Asymptotic profile of solutions for semilinear wave equations with structural damping
This paper is concerned with the initial value problem for semilinear wave equation with structural damping $u_{tt}+(-\Delta)^{\sigma}u_t -\Delta u =f(u)$, where $\sigma \in (0,\frac{1}{2})$ and $f(u) \sim |u|^p$ or $u |u|^{p-1}$ with $p> 1 + {2}/(n - 2 \sigma)$. We first show the global existence for initial data smal...
1807.05509v3
2018-07-19
Vibrational damping effects on electronic energy relaxation in molecular aggregates
Representation of molecular vibrational degrees of freedom by independent harmonic oscillators, when describing electronic spectra or electronic excitation energy transport, raises unfavourable effects as vibrational energy relaxation becomes inaccessible. A standard theoretical description is extended in this paper by...
1807.07314v1
2018-07-24
Role of stable modes in driven shear-flow turbulence
A linearly unstable, sinusoidal $E \times B$ shear flow is examined in the gyrokinetic framework in both the linear and nonlinear regimes. In the linear regime, it is shown that the eigenmode spectrum is nearly identical to hydrodynamic shear flows, with a conjugate stable mode found at every unstable wavenumber. In th...
1807.09280v1
2018-08-08
An application of $L^1$ estimates for oscillating integrals to parabolic like semi-linear structurally damped $σ$-evolution models
We study the following Cauchy problems for semi-linear structurally damped $\sigma$-evolution models: \begin{equation*} u_{tt}+ (-\Delta)^\sigma u+ \mu (-\Delta)^\delta u_t = f(u,u_t),\, u(0,x)= u_0(x),\, u_t(0,x)=u_1(x) \end{equation*} with $\sigma \ge 1$, $\mu>0$ and $\delta \in (0,\frac{\sigma}{2})$. Here the functi...
1808.02706v2
2018-08-09
Two-qubit state recovery from amplitude damping based on weak measurement
In the quantum control process, arbitrary pure or mixed initial states need to be protected from amplitude damping through the noise channel using measurements and quantum control. However, how to achieve it on a two-qubit quantum system remains a challenge. In this paper, we propose a feed-forward control approach to ...
1808.03094v1
2018-08-10
Dynamical polarization and the optical response of silicene and related materials
We discuss the dynamical polarization, optical response in low-frequency regime under in-plane polarized driving field of the silicene. The dynamical polarization, dielectric function, and absorption of radiation in infrared region are obtained and shown in the ${\bf q}\sim\omega$ space, and they are distinguishing for...
1808.03442v1
2018-08-19
Reconstruction algorithms for photoacoustic tomography in heterogenous damping media
In this article, we study several reconstruction methods for the inverse source problem of photoacoustic tomography (PAT) with spatially variable sound speed and damping. The backbone of these methods is the adjoint operators, which we thoroughly analyze in both the $L^2$- and $H^1$-settings. They are casted in the for...
1808.06176v1
2018-08-27
Landau damping of Alfvénic modes in stellarators
It is found that the presence of the so-called non-axisymmetric resonances of wave-particle interaction in stellarators [which are associated with the lack of axial symmetry of the magnetic configuration, Kolesnichenko et al., Phys. Plasmas 9 (2002) 517] may have a strong stabilizing influence through Landau mechanism ...
1808.08862v1
2018-09-04
Linear Wave Propagation for Resistive Relativistic Magnetohydrodynamics
We present a linear mode analysis of the relativistic MHD equations in the presence of finite electrical conductivity. Starting from the fully relativistic covariant formulation, we derive the dispersion relation in the limit of small linear perturbations. It is found that the system supports ten wave modes which can b...
1809.01115v1
2018-09-05
NMR-like effect on Anisotropic Magnetic Moment of Surface Bound States in Topological Superfluid $^3$He-B
We present experimental observation of a new phenomenon, that we interpret as NMR-like effect on anisotropic magnetic moment of the surface Andreev bound states in topological superfluid $^3$He-B at zero temperature limit. We show that an anisotropic magnetic moment formed near the horizontal surface of a mechanical re...
1809.01402v3
2018-09-11
Optomechanical damping basis
We present a closed-form analytical solution to the eigenvalue problem of the Liouville operator generating the dissipative dynamics of the standard optomechanical system. The corresponding Lindblad master equation describes the dynamics of a single-mode field inside an optical cavity coupled by radiation pressure to i...
1809.03693v2
2018-09-13
Active Damping of a DC Network with a Constant Power Load: An Adaptive Passivity-based Control Approach
This paper proposes a nonlinear, adaptive controller to increase the stability margin of a direct-current (DC) small-scale electrical network containing a constant power load, whose value is unknown. Due to their negative incremental impedance, constant power loads are known to reduce the effective damping of a network...
1809.04920v1
2018-09-14
Nonequilibrium polariton dynamics in a Bose-Einstein condensate coupled to an optical cavity
We study quasiparticle scattering effects on the dynamics of a homogeneous Bose-Einstein condensate of ultracold atoms coupled to a single mode of an optical cavity. The relevant excitations, which are polariton-like mixed excitations of photonic and atomic density-wave modes, are identified. All the first-order correl...
1809.05427v2
2018-09-26
The influence of oscillations on energy estimates for damped wave models with time-dependent propagation speed and dissipation
The aim of this paper is to derive higher order energy estimates for solutions to the Cauchy problem for damped wave models with time-dependent propagation speed and dissipation. The model of interest is \begin{equation*} u_{tt}-\lambda^2(t)\omega^2(t)\Delta u +\rho(t)\omega(t)u_t=0, \quad u(0,x)=u_0(x), \,\, u_t(0,x)=...
1809.10179v2
2018-09-27
Non-equilibrium Quantum Langevin dynamics of orbital diamagnetic moment
We investigate the time dependent orbital diamagnetic moment of a charged particle in a magnetic field in a viscous medium via the Quantum Langevin Equation. We study how the interplay between the cyclotron frequency and the viscous damping rate governs the dynamics of the orbital magnetic moment in the high temperatur...
1809.10370v1
2018-09-29
Uniform stabilization for the Klein-Gordon system in a inhomogeneous medium with locally distributed damping
We consider the Klein-Gordon system posed in an inhomogeneous medium with smooth boundary subject to a local viscoelastic damping distributed around a neighborhoodof the boundary according to the Geometric Control Condition. We show that the energy of the system goes uniformly and exponentially to zero for all initial ...
1810.00247v1
2018-10-09
Lévy-walk-like Langevin dynamics
Continuous time random walks and Langevin equations are two classes of stochastic models for describing the dynamics of particles in the natural world. While some of the processes can be conveniently characterized by both of them, more often one model has significant advantages (or has to be used) compared with the oth...
1810.04332v1
2018-10-18
Analysis of the controllability from the exterior of strong damping nonlocal wave equations
We make a complete analysis of the controllability properties from the exterior of the (possible) strong damping wave equation with the fractional Laplace operator subject to the nonhomogeneous Dirichlet type exterior condition. In the first part, we show that if $0<s<1$, $\Omega\subset\RR^N$ ($N\ge 1$) is a bounded Li...
1810.08060v1
2018-10-20
Memory-based mediated interactions between rigid particulate inclusions in viscoelastic environments
Many practically relevant materials combine properties of viscous fluids and elastic solids to viscoelastic behavior. Our focus is on the induced dynamic behavior of damped finite-sized particulate inclusions in such substances. We explicitly describe history-dependent interactions that emerge between the embedded part...
1810.08832v1
2018-10-22
Dynamical instability towards finite-momentum pairing in quenched BCS superconducting phases
In this work we numerically investigate the fate of the Bardeen-Cooper-Schrieffer (BCS) pairing in the presence of quenched phase under Peierls substitution using time-dependent real space and momentum space Bogoliubov-de Gennes equation methods and Anderson pseudospin representation method. This kind of phase imprint ...
1810.09125v1
2018-10-21
A note on a weakly coupled system of semi-linear visco-elastic damped $σ$-evolution models with different power nonlinearities and different $σ$ values
In this article, we prove the global (in time) existence of small data solutions from energy spaces basing on $L^q$ spaces, with $q \in (1,\infty)$, to the Cauchy problems for a weakly coupled system of semi-linear visco-elastic damped $\sigma$-evolution models. Here we consider different power nonlinearities and diffe...
1810.09664v1
2018-10-25
First-principles calculation of spin-orbit torque in a Co/Pt bilayer
The angular dependence of spin-orbit torque in a disordered Co/Pt bilayer is calculated using a first-principles non-equilibrium Green's function formalism with an explicit supercell averaging over Anderson disorder. In addition to the usual dampinglike and fieldlike terms, the odd torque contains a sizeable planar Hal...
1810.11003v2
2018-10-29
Optimal identification of non-Markovian environments for spin chains
Correlations of an environment are crucial for the dynamics of non-Markovian quantum systems, which may not be known in advance. In this paper, we propose a gradient algorithm for identifying the correlations in terms of time-varying damping rate functions in a time-convolution-less master equation for spin chains. By ...
1810.11923v1
2018-10-29
Existence and uniqueness of dynamic evolutions for a one-dimensional debonding model with damping
In this paper we analyse a one-dimensional debonding model for a thin film peeled from a substrate when viscosity is taken into account. It is described by the weakly damped wave equation whose domain, the debonded region, grows according to a Griffith's criterion. Firstly we prove that the equation admits a unique sol...
1810.12006v3
2018-10-29
A Graceful Exit for the Cosmological Constant Damping Scenario
We present a broad and simple class of scalar-tensor scenarios that successfully realize dynamical damping of the effective cosmological constant, therefore providing a viable dynamical solution to the fine-tuning or "old" cosmological constant problem. In contrast to early versions of this approach, pioneered in the w...
1810.12336v2
2018-10-31
AGN Variability Analysis Handbook
This work develops application techniques for stochastic modelling of Active Galactic Nuclei (AGN) variability as a probe of accretion disk physics. Stochastic models, specifically Continuous Auto-Regressive Moving Average (CARMA) models, characterize lightcurves by estimating delay timescales that describe movements a...
1811.00154v1
2018-11-15
Unique ergodicity for a class of stochastic hyperbolic equations with additive space-time white noise
In this paper, we consider a certain class of second order nonlinear PDEs with damping and space-time white noise forcing, posed on the $d$-dimensional torus. This class includes the wave equation for $d=1$ and the beam equation for $d\le 3$. We show that the Gibbs measure of the equation without forcing and damping is...
1811.06294v4
2018-12-04
Optical excitation of single- and multi-mode magnetization precession in Galfenol nanolayers
We demonstrate a variety of precessional responses of the magnetization to ultrafast optical excitation in nanolayers of Galfenol (Fe,Ga), which is a ferromagnetic material with large saturation magnetization and enhanced magnetostriction. The particular properties of Galfenol, including cubic magnetic anisotropy and w...
1812.01237v1
2018-12-10
Assessment of skin-friction-reduction techniques on a turbulent wing section
The scope of the present project is to quantify the effects of uniform blowing and body-force damping on turbulent boundary layers subjected to a non-uniform adverse-pressure-gradient distribution. To this end, well-resolved large-eddy simulations are employed to describe the flow around the NACA4412 airfoil at moderat...
1812.03762v1
2018-12-18
Gravitational quasinormal modes of black holes in Einstein-aether theory
The local Lorentz violation (LV) in gravity sector should show itself in derivation of the characteristic quasinormal modes (QNMs) of black hole mergers from their general relativity case. In this paper, I study QNMs of the gravitational field perturbations to Einstein-aether black holes and, at first compare them to t...
1812.07994v1
2018-12-19
Rain Calms the Sea - The Impact of Entrained Air
We propose a mechanism for the damping of short ocean gravity waves during rainstorms associated with the injection of air bubbles by rain drops. The mechanism is proposed as one of the possible explanations that ascribe to rain a calming effect on ocean surface waves. A model is developed that shows how wave attenuati...
1812.08200v2
2018-12-25
Blow-up for a weakly coupled system of semilinear damped wave equations in the scattering case with power nonlinearities
In this work we study the blow-up of solutions of a weakly coupled system of damped semilinear wave equations in the scattering case with power nonlinearities. We apply an iteration method to study both the subcritical case and the critical case. In the subcritical case our approach is based on lower bounds for the spa...
1812.10086v1
2018-12-27
Global existence of solutions to semilinear damped wave equation with slowly decaying inital data in exterior domain
In this paper, we discuss the global existence of weak solutions to the semilinear damped wave equation \begin{equation*} \begin{cases} \partial_t^2u-\Delta u + \partial_tu = f(u) & \text{in}\ \Omega\times (0,T), \\ u=0 & \text{on}\ \partial\Omega\times (0,T), \\ u(0)=u_0, \partial_tu(0)=u_1 & \text{in}\ \Omega, \end{c...
1812.10664v1
2018-12-28
Axion Misalignment Driven to the Bottom
Several theoretical motivations point to ultralight QCD axions with large decay constants $f_a \simeq \mathcal{O}(10^{16}-10^{17})$ GeV, to which experimental proposals are dedicated. This regime is known to face the problem of overproduction of axion dark matter from the misalignment mechanism unless the misalignment ...
1812.11186v2
2019-01-03
Calibration and Status of the 3D Imaging Calorimeter of DAMPE for Cosmic Ray Physics on Orbit
The DArk Matter Particle Explorer (DAMPE) developed in China was designed to search for evidence of dark matter particles by observing primary cosmic rays and gamma rays in the energy range from 5 GeV to 10 TeV. Since its launch in December 2015, a large quantity of data has been recorded. With the data set acquired du...
1901.00734v1
2019-01-08
Atom-only descriptions of the driven-dissipative Dicke model
We investigate how to describe the dissipative spin dynamics of the driven-dissipative Dicke model, describing $N$ two-level atoms coupled to a cavity mode, after adiabatic elimination of the cavity mode. To this end, we derive a Redfield master equation which goes beyond the standard secular approximation and large de...
1901.02473v2
2019-01-10
Stability and Controllability results for a Timoshenko system
In this paper, we study the indirect boundary stability and exact controllability of a one-dimensional Timoshenko system. In the first part of the paper, we consider the Timoshenko system with only one boundary fractional damping. We first show that the system is strongly stable but not uniformly stable. Hence, we look...
1901.03303v2
2019-01-13
Dueling Dynamical Backaction in a Cryogenic Optomechanical Cavity
Dynamical backaction has proven to be a versatile tool in cavity optomechanics, allowing for precise manipulation of a mechanical resonator's motion using confined optical photons. In this work, we present measurements of a silicon whispering-gallery-mode optomechanical cavity where backaction originates from opposing ...
1901.03950v1
2019-01-22
Coupling between superfluid neutrons and superfluid protons in the elementary excitations of neutron star matter
Several phenomena occurring in neutron stars are affected by the elementary excitations that characterize the stellar matter. In particular, low-energy excitations can play a major role in the emission and propagation of neutrinos, neutron star cooling and transport processes. In this paper, we consider the elementary ...
1901.07550v1
2019-02-08
Milky Way Halo Vibrations and Incommensurate Stream Velocities
Collisionless dark matter galactic halos are expected to exhibit damped oscillations as a result of ongoing late time accretion. An n-body model of the cosmological assembly of a Milky Way-like halo is used to quantify the time dependence of its gravitational field. The simulation contains stellar streams whose incomme...
1902.03275v2
2019-02-20
Dark matter gets DAMPE at high energies
The DArk Matter Particle Explorer (DAMPE) mission revealed a break in the spectrum of cosmic-ray electons and positrons. This is associated with an excess above the expected backgrounds at energies around 1 TeV. Several authors have argued that such an excess can be explained in terms of dark matter models that feature...
1902.07468v1
2019-02-23
General symmetry in the reduced dynamics of two-level system
We study general transformation on the density matrix of two-level system that keeps the expectation value of observable invariant. We introduce a set of generators that yields hermiticity and trace preserving general transformation which casts the transformation into simple form. The general transformation is in gener...
1902.08714v2
2019-02-25
Interpretation of the cosmic ray positron and electron excesses with an annihilating-decaying dark matter scenario
The precise measurements of energy spectra of cosmic ray positrons and/or electrons by recent experiments show clear excesses above 10 GeV. Moreover, a potential sharp spectral feature was suggested by the Dark Matter Particle Explorer (DAMPE) data. These results inspire quite a number of discussions on the connection ...
1902.09235v2