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2014-02-20
Starobinsky-Like Inflation in Dilaton-Brane Cosmology
We discuss how Starobinsky-like inflation may emerge from dilaton dynamics in brane cosmology scenarios based on string theory, in which our universe is represented as a three-brane. The effective potential may acquire a constant term from a density of effectively point-like non-pertubative defects on the brane. Higher...
1402.5075v2
2014-02-24
Universal High Order Subroutine with New Shock Detector for Shock Boundary Layer Interaction
The goal of this work is to develop a new universal high order subroutine for shock boundary layer interaction. First, an effective shock/discontinuity detector has been developed.The detector has two steps.The first step is to check the ratio of the truncation errors on the coarse and fine grids and the second step is...
1402.5885v1
2014-03-25
Fluctuation-dissipation relations for a plasma-kinetic Langevin equation
A linearised kinetic equation describing electrostatic perturbations of a Maxwellian equilibrium in a weakly collisional plasma forced by a random source is considered. The problem is treated as a kinetic analogue of the Langevin equation and the corresponding fluctuation-dissipation theorem is derived. This kinetic fl...
1403.6257v3
2014-05-29
Dynamical spin response in cuprate superconductors from low-energy to high-energy
Within the framework of the kinetic energy driven superconducting mechanism, the dynamical spin response of cuprate superconductors is studied from low-energy to high-energy. The spin self-energy is evaluated explicitly in terms of the collective charge carrier modes in the particle-hole and particle-particle channels,...
1405.7448v2
2014-07-11
Chiral Hall Effect and Chiral Electric Waves
We investigate the vector and axial currents induced by external electromagnetic fields and chemical potentials in chiral systems at finite temperature. Similar to the normal Hall effect, we find that an axial Hall current is generated in the presence of the electromagnetic fields along with an axial chemical potential...
1407.3168v3
2014-08-29
Thermal pairing and giant dipole resonance in highly excited nuclei
Recent results are reported showing the effects of thermal pairing in highly excited nuclei. It is demonstrated that thermal pairing included in the phonon damping model (PDM) is responsible for the nearly constant width of the giant dipole resonance (GDR) at low temperature $T <$ 1 MeV. It is also shown that the enhan...
1408.6905v1
2014-12-23
Classical Noether's theory with application to the linearly damped particle
This paper provides a modern presentation of Noether's theory in the realm of classical dynamics, with application to the problem of a particle submitted to both a potential and a linear dissipation. After a review of the close relationships between Noether symmetries and first integrals, we investigate the variational...
1412.7523v2
2015-01-12
A New Fate of a Warped 5D FRW Model with a U(1) Scalar Gauge Field
If we live on the weak brane with zero effective cosmological constant in a warped 5D bulk spacetime, gravitational waves and brane fluctuations can be generated by a part of the 5D Weyl tensor and carries information of the gravitational field outside the brane. We consider on a cylindrical symmetric warped FRW backgr...
1501.02843v5
2015-03-01
Generalized spectral method for near-field optical microscopy
Electromagnetic interaction between a sub-wavelength particle (the `probe') and a material surface (the `sample') is studied theoretically. The interaction is shown to be governed by a series of resonances corresponding to surface polariton modes localized near the probe. The resonance parameters depend on the dielectr...
1503.00221v2
2015-03-09
Boundedness in a quasilinear fully parabolic Keller-Segel system of higher dimension with logistic source
This paper deals with the higher dimension quasilinear parabolic-parabolic Keller-Segel system involving a source term of logistic type $ u_t=\nabla\cdot(\phi(u)\nabla u)-\chi\nabla\cdot(u\nabla v)+g(u)$, $\tau v_t=\Delta v-v+u$ in $\Omega\times (0,T)$, subject to nonnegative initial data and homogeneous Neumann bounda...
1503.02387v1
2015-04-29
Stability of rings around a triaxial primary
Generally, the oblateness of a planet or moon is what causes rings to settle into its equatorial plane. However, the recent suggestion that a ring system might exist (or have existed) about Rhea, a moon whose shape includes a strong prolate component pointed toward Saturn, raises the question of whether rings around a ...
1504.07807v1
2015-05-06
Application of optimal homotopy asymptotic method to nonlinear Bingham fluid dampers
Magnetorheological fluids (MR) are stable suspensions of magnetizable microparticles, characterized by the property to change the rheological characteristics when subjected to the action of magnetic field. Together with another class of materials that change their rheological characteristics in the presence of an elect...
1505.01322v1
2015-06-28
Slimplectic Integrators: Variational Integrators for General Nonconservative Systems
Symplectic integrators are widely used for long-term integration of conservative astrophysical problems due to their ability to preserve the constants of motion; however, they cannot in general be applied in the presence of nonconservative interactions. In this Letter, we develop the "slimplectic" integrator, a new typ...
1506.08443v3
2015-09-28
Breaking a Dark Degeneracy with Gravitational Waves
We identify a scalar-tensor model embedded in the Horndeski action whose cosmological background and linear scalar fluctuations are degenerate with the concordance cosmology. The model admits a self-accelerated background expansion at late times that is stable against perturbations with a sound speed attributed to the ...
1509.08458v2
2015-12-02
Thermodynamics of the heat currents in the longitudinal spin Seebeck and spin Peltier effects
We employ the non-equilibrium thermodynamics of currents and forces to describe the heat transport caused by a spin current in a Pt/YIG bilayer. By starting from the constitutive equations of the magnetization currents in both Pt and YIG, we derive the magnetization potentials and currents. We apply the theory to the s...
1512.00644v2
2015-12-11
Infrared study of lattice dynamics and spin-phonon and electron-phonon interactions in multiferroic TbFe3(BO3)4 and GdFe3(BO3)4
We present a comparative far-infrared reflection spectroscopy study of phonons, phase transitions, spin-phonon and electron-phonon interactions in isostructural multiferroic iron borates of gadolinium and terbium. The behavior of phonon modes registered in a wide temperature range is consistent with a weak first-order ...
1512.03527v1
2015-12-27
Electrically Switchable Metadevices via Graphene
Metamaterials bring sub-wavelength resonating structures together to overcome the limitations of conventional materials. The realization of active metadevices has been an outstanding challenge that requires electrically reconfigurable components operating over a broad spectrum with a wide dynamic range. The existing ca...
1512.08277v3
2016-02-03
Extending the velocity-dependent one-scale model for domain walls
We report on an extensive study of the evolution of domain wall networks in Friedmann-Lema\^{\i}tre-Robertson-Walker universes by means of the largest currently available field-theory simulations. These simulations were done in $4096^3$ boxes and for a range of different fixed expansion rates, as well as for the transi...
1602.01322v2
2016-02-06
Basic Properties of Conductivity and Normal Hall Effect in the Periodic Anderson Model
Exact formulas of diagonal conductivity $\sigma_{xx}$ and Hall conductivity $\sigma_{xy}$ are derived from the Kubo formula in hybridized two-orbital systems with arbitrary band dispersions. On the basis of the theoretical framework for the Fermi liquid based on these formulas, the ground-state properties of the period...
1602.02229v1
2016-04-18
Anisotropic magnetization relaxation in ferromagnetic multilayers with variable interlayer exchange coupling
The FMR linewidth and its anisotropy in F$_1$/f/F$_2$/AF multilayers, where spacer f has a low Curie point compared to the strongly ferromagnetic F$_1$ and F$_2$, is investigated. The role of the interlayer exchange coupling in magnetization relaxation is determined experimentally by varying the thickness of the spacer...
1604.05145v1
2016-05-04
Athermal rheology of weakly attractive soft particles
We study the rheology of a soft particulate system where the inter-particle interactions are weakly attractive. Using extensive molecular dynamics simulations, we scan across a wide range of packing fractions ($\phi$), attraction strengths ($u$) and imposed shear-rates ($\dot{\gamma}$). In striking contrast to repulsiv...
1605.01222v4
2016-05-05
Fractional Brownian motion, the Matern process, and stochastic modeling of turbulent dispersion
Stochastic process exhibiting power-law slopes in the frequency domain are frequently well modeled by fractional Brownian motion (fBm). In particular, the spectral slope at high frequencies is associated with the degree of small-scale roughness or fractal dimension. However, a broad class of real-world signals have a h...
1605.01684v3
2016-06-16
Calculating rotating hydrodynamic and magneto-hydrodynamic waves to understand magnetic effects on dynamical tides
For understanding magnetic effects on dynamical tides, we study the rotating magneto-hydrodynamic (MHD) flow driven by harmonic forcing. The linear responses are analytically derived in a periodic box under the local WKB approximation. Both the kinetic and Ohmic dissipations at the resonant frequencies are calculated a...
1606.06232v1
2016-08-07
Two-loop RGE of a general renormalizable Yang-Mills theory in a renormalization scheme with an explicit UV cutoff
We perform a systematic one-loop renormalization of a general renormalizable Yang-Mills theory coupled to scalars and fermions using a regularization scheme with a smooth momentum cutoff $\Lambda$ (implemented through an exponential damping factor). We construct the necessary finite counterterms restoring the BRST inva...
1608.02270v3
2016-10-11
On the free-precession candidate PSR B1828-11: Evidence for increasing deformation
We observe that the periodic variations in spin-down rate and beam-width of the radio pulsar PSR B1828-11 are getting faster. In the context of a free precession model, this corresponds to a decrease in the precession period $P_{\mathrm{fp}}$. We investigate how a precession model can account for such a decrease in $P_...
1610.03508v3
2016-10-24
Low-power photothermal self-oscillation of bimetallic nanowires
We investigate the nonlinear mechanics of a bimetallic, optically absorbing SiN-Nb nanowire in the presence of incident laser light and a reflecting Si mirror. Situated in a standing wave of optical intensity and subject to photothermal forces, the nanowire undergoes self-induced oscillations at low incident light thre...
1610.07591v4
2016-11-21
Relativistic orbits around spinning supermassive black holes. Secular evolution to 4.5 post-Newtonian order
We derive the secular evolution of the orbital elements of a stellar-mass object orbiting a spinning massive black hole. We use the post-Newtonian approximation in harmonic coordinates, with test-body equations of motion for the conservative dynamics that are valid through 3PN order, including spin-orbit, quadrupole an...
1611.06931v1
2016-12-01
Echoes from the Abyss: Tentative evidence for Planck-scale structure at black hole horizons
In classical General Relativity (GR), an observer falling into an astrophysical black hole is not expected to experience anything dramatic as she crosses the event horizon. However, tentative resolutions to problems in quantum gravity, such as the cosmological constant problem, or the black hole information paradox, in...
1612.00266v2
2016-12-21
Cosmological singularity resolution from quantum gravity: the emergent-bouncing universe
Alternative scenarios to the Big Bang singularity have been subject of intense research for several decades by now. Most popular in this sense have been frameworks were such singularity is replaced by a bounce around some minimal cosmological volume or by some early quantum phase. This latter scenario was devised a lon...
1612.07116v2
2017-01-12
Dynamic coupling of ferromagnets via spin Hall magnetoresistance
The synchronized magnetization dynamics in ferromagnets on a nonmagnetic heavy metal caused by the spin Hall effect is investigated theoretically. The direct and inverse spin Hall effects near the ferromagnetic/nonmagnetic interface generate longitudinal and transverse electric currents. The phenomenon is known as the ...
1701.03201v2
2017-02-09
Damped spin excitations in a doped cuprate superconductor with orbital hybridization
A resonant inelastic x-ray scattering (RIXS) study of overdamped spin-excitations in slightly underdoped La$_{2-x}$Sr$_{x}$CuO$_4$ (LSCO) with $x=0.12$ and $0.145$ is presented. Three high-symmetry directions have been investigated: (1) the antinodal $(0,0)\rightarrow (1/2,0)$, (2) the nodal $(0,0)\rightarrow (1/4,1/4)...
1702.02782v3
2017-02-24
Dicke Phase Transition and Collapse of Superradiant Phase in Optomechanical Cavity with Arbitrary Number of Atoms
We in this paper derive the analytical expressions of ground-state energy, average photon-number, and the atomic population by means of the spin-coherent-state variational method for arbitrary number of atoms in an optomechanical cavity. It is found that the existence of mechanical oscil- lator does not affect the phas...
1702.07438v1
2017-02-28
Photon-Axion Conversion, Magnetic Field Configuration, and Polarization of Photons
We study the evolution of photon polarization during the photon-axion conversion process with focusing on the magnetic field configuration dependence. Most previous studies have been carried out in a conventional model where a network of magnetic domains is considered and each domain has a constant magnetic field. We i...
1702.08843v2
2017-03-17
Quasinormal modes of a scalar field in the Einstein--Gauss--Bonnet-AdS black hole background: Perturbative and non-perturbative branches
It has recently been found that quasinormal modes of asymptotically anti-de Sitter (AdS) black holes in theories with higher curvature corrections may help to describe the regime of intermediate 't Hooft coupling in the dual field theory. Here, we consider quasinormal modes of a scalar field in the background of spheri...
1703.06215v3
2017-05-19
A Superior but Equally Convenient Alternative to the Steady-State Approximation and Secular Equilibrium
The steady-state approximation (hereafter abbreviated as SSA) consists in setting $dy/dt=0$, where $y$ denotes the concentration of a short-lived intermediate subject to first-order decay with a rate constant $k$. The sole reason for enforcing SSA is to convert the rate equation for $y$ into an algebraic equation. The ...
1705.08749v2
2017-06-21
Spectral analysis and multigrid preconditioners for two-dimensional space-fractional diffusion equations
Fractional diffusion equations (FDEs) are a mathematical tool used for describing some special diffusion phenomena arising in many different applications like porous media and computational finance. In this paper, we focus on a two-dimensional space-FDE problem discretized by means of a second order finite difference s...
1706.06844v1
2017-07-07
Interplay between the edge-state magnetism and long-range Coulomb interaction in zigzag graphene nanoribbons: quantum Monte Carlo study
We perform projective quantum Monte Carlo simulations of zigzag graphene nanoribbons within a realistic model with long-range Coulomb interactions. Increasing the relative strength of nonlocal interactions with respect to the on-site repulsion does not generate a phase transition but has a number of nontrivial effects....
1707.02065v2
2017-09-30
Tuning the diffusion of magnon in Y3Fe5O12 by light excitation
Deliberate control of magnon transportation will lead to an energy-efficient technology for information transmission and processing. Y3Fe5O12(YIG), exhibiting extremely large magnon diffusion length due to the low magnetic damping constant, has been intensively investigated for decades. While most of the previous works...
1710.00222v2
2017-10-19
Global performance metrics for synchronization of heterogeneously rated power systems: The role of machine models and inertia
A recent trend in control of power systems has sought to quantify the synchronization dynamics in terms of a global performance metric, compute it under very simplified assumptions, and use it to gain insight on the role of system parameters, in particular, inertia. In this paper, we wish to extend this approach to mor...
1710.07195v4
2017-12-20
Second-harmonic magnetic response characterizing magnetite-based colloid
Nonlinear second-harmonic magnetic response (M2) was used to characterize an aqueous colloidal solution of dextran-coated magnetite (Fe3O4) nanoparticles. Data analysis with the formalism based on Gilbert-Landau-Lifshitz equation for stochastic dynamics of superparamagnetic (SP) particles ensured extensive quantifying ...
1712.07534v1
2018-02-09
Monocrystalline free standing 3D yttrium iron garnet magnon nano resonators
Nano resonators in which mechanical vibrations and spin waves can be coupled are an intriguing concept that can be used in quantum information processing to transfer information between different states of excitation. Until now, the fabrication of free standing magnetic nanostructures which host long lived spin wave ex...
1802.03176v2
2018-03-07
Rapidly forming, slowly evolving, spatial patterns from quasi-cycle Mexican Hat coupling
A lattice-indexed family of stochastic processes has quasi-cycle oscillations if its otherwise-damped oscillations are sustained by noise. Such a family performs the reaction part of a discrete stochastic reaction-diffusion system when we insert a local Mexican Hat-type, difference of Gaussians, coupling on a one-dimen...
1803.02917v2
2018-03-23
Observation of hedgehog skyrmions in sub-100 nm soft magnetic nanodots
Magnetic skyrmions are nanometric spin textures of outstanding potential for spintronic applications due to unique features governed by their non-trivial topology. It is well known that skyrmions of definite chirality are stabilized by the Dzyaloshinskii-Moriya exchange interaction (DMI) in bulk non-centrosimmetric mat...
1803.08768v1
2018-05-08
Fitting a function to time-dependent ensemble averaged data
Time-dependent ensemble averages, i.e., trajectory-based averages of some observable, are of importance in many fields of science. A crucial objective when interpreting such data is to fit these averages (for instance, squared displacements) with a function and extract parameters (such as diffusion constants). A common...
1805.03057v1
2018-05-22
Time dilation in the oscillating decay laws of moving two-mass unstable quantum states
The decay of a moving system is studied in case the system is initially prepared in a two-mass unstable quantum state. The survival probability $\mathcal{P}_p(t)$ is evaluated over short and long times in the reference frame where the unstable system moves with constant linear momentum $p$. The mass distribution densit...
1805.08335v1
2018-05-23
The classical D-type expansion of spherical H II regions
Recent numerical and analytic work has highlighted some shortcomings in our understanding of the dynamics of H II region expansion, especially at late times, when the H II region approaches pressure equilibrium with the ambient medium. Here we reconsider the idealized case of a constant radiation source in a uniform an...
1805.09273v1
2018-05-24
Quantum surface diffusion in Bohmian Mechanics
Surface diffusion of small adsorbates is analyzed in terms of the so-called intermediate scattering function and dynamic structure factor, observables in experiments using the well-known quasielastic Helium atom scattering and Helium spin echo techniques. The linear theory used is an extension of the neutron scattering...
1805.09536v5
2018-08-13
A Nonsmooth Dynamical Systems Perspective on Accelerated Extensions of ADMM
Recently, there has been great interest in connections between continuous-time dynamical systems and optimization methods, notably in the context of accelerated methods for smooth and unconstrained problems. In this paper we extend this perspective to nonsmooth and constrained problems by obtaining differential inclusi...
1808.04048v7
2018-09-20
Relaxation in a Fuzzy Dark Matter Halo
Dark matter may be composed of light bosons, ${m_b \sim 10^{-22}\, \mathrm{eV}}$, with a de Broglie wavelength $\lambda \sim 1 \,\mathrm{kpc}$ in typical galactic potentials. Such `fuzzy' dark matter (FDM) behaves like cold dark matter (CDM) on much larger scales than the de Broglie wavelength, but may resolve some of ...
1809.07673v2
2018-10-02
How strongly does diffusion or logistic-type degradation affect existence of global weak solutions in a chemotaxis-Navier--Stokes system?
This paper considers the chemotaxis-Navier--Stokes system with nonlinear diffusion and logistic-type degradation term \begin{align*} \begin{cases} n_t + u\cdot\nabla n = \nabla \cdot(D(n)\nabla n) - \nabla\cdot(n \chi(c) \nabla c) + \kappa n - \mu n^\alpha, & x\in \Omega,\ t>0, \\ c_t + u\cdot\nabla c = \Delta c - nf(c...
1810.01098v2
2018-10-05
Magnetic field direction dependent antiskyrmion motion with microwave electric fields
Magnetic skyrmions are regarded as promising information candidates in future spintronic devices, which have been investigated theoretically and experimentally in isotropic system. Recently, the sta- bilization of antiskyrmions in the presence of anisotropic Dzyaloshinskii-Moriya interaction and its dynamics driven by ...
1810.02464v1
2018-10-22
Polarized Raman spectroscopy study of metallic $(Sr_{1-x}La_{x})_{3}Ir_{2}O_{7}$: a consistent picture of disorder-interrupted unidirectional charge order
We have used rotational anisotropic polarized Raman spectroscopy to study the symmetries, the temperature and the doping dependence of the charge ordered state in metallic $(Sr_{1-x}La_{x})_{3}Ir_{2}O_{7}$. Although the Raman probe size is greater than the charge ordering length, we establish that the charge ordering b...
1810.09087v2
2018-11-30
Dynamical precession of spin in the two-dimensional spin-orbit coupled systems
We investigate the spin dynamics in the two-dimensional spin-orbit coupled system subject to an in-plane ($x$-$y$ plane) constant electric field, which is assumed to be turned on at the moment $t=0$. The equation of spin precession in linear response to the switch-on of the electric field is derived in terms of Heisenb...
1811.12626v2
2019-01-25
Gravitational waves from dynamical tides in white dwarf binaries
We study the effect of tidal forcing on gravitational wave signals from tidally relaxed white dwarf pairs in the LISA, DECIGO and BBO frequency band ($0.1-100\,{\rm mHz}$). We show that for stars not in hydrostatic equilibrium (in their own rotating frames), tidal forcing will result in energy and angular momentum exch...
1901.09045v2
2019-01-31
Angular momentum Josephson effect between two isolated condensates
We demonstrate that the two degenerate energy levels in spin-orbit coupled trapped Bose gases, coupled by a quenched Zeeman field, can be used for angular momentum Josephson effect. In a static quenched field, we can realize a Josephson oscillation with period ranging from millisecond to hundreds of milliseconds. Moreo...
1901.11449v2
2019-03-27
Field-free spin-orbit-torque switching of perpendicular magnetization aided by uniaxial shape anisotropy
It has been demonstrated that the switching of perpendicular magnetization can be achieved with spin orbit torque (SOT) at an ultrafast speed and low energy consumption. However, to make the switching deterministic, an undesirable magnetic field or unconventional device geometry is required to break the structure inver...
1903.11487v1
2019-06-18
Nonlinear Langevin dynamics via holography
In this work, we consider non-linear corrections to the Langevin effective theory of a heavy quark moving through a strongly coupled CFT plasma. In AdS/CFT, this system can be identified with that of a string stretched between the boundary and the horizon of an asymptotically AdS black-brane solution. We compute the Fe...
1906.07762v3
2019-06-24
Emergence of localized persistent weakly-evanescent cortical brain wave loops
An inhomogeneous anisotropic physical model of the brain cortex is presented that predicts the emergence of non--evanescent (weakly damped) wave--like modes propagating in the thin cortex layers transverse to both the mean neural fiber direction and to the cortex spatial gradient. Although the amplitude of these modes ...
1906.09717v1
2019-12-16
Spin-current manipulation of photoinduced magnetization dynamics in heavy metal / ferromagnet double layer based nanostructures
Spin currents offer a way to control static and dynamic magnetic properties, and therefore they are crucial for next-generation MRAM devices or spin-torque oscillators. Manipulating the dynamics is especially interesting within the context of photo-magnonics. In typical $3d$ transition metal ferromagnets like CoFeB, th...
1912.07728v1
2019-12-18
Tidal evolution of circumbinary systems with arbitrary eccentricities: applications for Kepler systems
We present an extended version of the Constant Time Lag analytical approach for the tidal evolution of circumbinary planets introduced in our previous work. The model is self-consistent, in the sense that all tidal interactions between pairs are computed, regardless of their size. We derive analytical expressions for t...
1912.08728v1
2020-01-01
Nonequilibrium Landau-Zener Tunneling in Exciton-Polariton Condensates
For a coherent quantum mechanical two-level system driven with a linearly time-dependent detuning, the Landau-Zener model has served over decades as a textbook model of quantum dynamics. A particularly intriguing question is whether that framework can be extended to capture an intrinsical nonequilibrium nature for a qu...
2001.00151v1
2020-01-14
A bound on the 12C/13C ratio in near-pristine gas with ESPRESSO
Using science verification observations obtained with ESPRESSO at the Very Large Telescope (VLT) in 4UT mode, we report the first bound on the carbon isotope ratio 12C/13C of a quiescent, near-pristine damped Ly-alpha (DLA) system at z=2.34. We recover a limit log10(12C/13C) > +0.37 (2 sigma). We use the abundance patt...
2001.04983v1
2020-01-14
Limits on Mode Coherence in Pulsating DA White Dwarfs Due to a Non-static Convection Zone
The standard theory of pulsations deals with the frequencies and growth rates of infinitesimal perturbations in a stellar model. Modes which are calculated to be linearly driven should increase their amplitudes exponentially with time; the fact that nearly constant amplitudes are usually observed is evidence that nonli...
2001.05048v1
2020-01-30
An auto-parameter denoising method for nuclear magnetic resonance spectroscopy based on low-rank Hankel matrix
Nuclear Magnetic Resonance (NMR) spectroscopy, which is modeled as the sum of damped exponential signals, has become an indispensable tool in various scenarios, such as the structure and function determination, chemical analysis, and disease diagnosis. NMR spectroscopy signals, however, are usually corrupted by Gaussia...
2001.11815v2
2020-02-26
Velocity-coherent Filaments in NGC 1333: Evidence for Accretion Flow?
Recent observations of global velocity gradients across and along molecular filaments have been interpreted as signs of gas accreting onto and along these filaments, potentially feeding star-forming cores and proto-clusters. The behavior of velocity gradients in filaments, however, has not been studied in detail, parti...
2002.11736v1
2020-02-25
The Casimir densities for a sphere in the Milne universe
The influence of a spherical boundary on the vacuum fluctuations of a massive scalar field is investigated in background of $(D+1)$-dimensional Milne universe, assuming that the field obeys Robin boundary condition on the sphere. The normalized mode functions are derived for the regions inside and outside the sphere an...
2003.05372v2
2020-03-12
Skyrmion Dynamics and Transverse Mobility: Skyrmion Hall Angle Reversal on 2D Periodic Substrates with dc and Biharmonic ac Drives
We numerically examine the dynamics of a skyrmion interacting with a two-dimensional periodic substrate under dc and biharmonic ac drives. We show that the Magnus force of the skyrmion produces circular orbits that can resonate with the ac drive and the periodicity of the substrate to create quantized motion both paral...
2003.05972v1
2020-03-16
Dimensional crossovers and Casimir forces for the Bose gas in anisotropic optical lattices
We consider the Bose gas on a $d$-dimensional anisotropic lattice employing the imperfect (mean-field) gas as a prototype example. We study the dimensional crossover arising as a result of varying the dispersion relation at finite temperature $T$. We analyze in particular situations where one of the relevant effective ...
2003.07458v3
2020-04-25
Quasinormal modes of the test fields in the novel 4D Einstein-Gauss-Bonnet-de Sitter gravity
The regularization proposed in [D.~Glavan and C.~Lin, Phys.\ Rev.\ Lett.\ {\bf 124}, 081301 (2020)] led to the black hole solutions which turned out to be the solutions of the consistent well-defined $4$-dimensional Einstein-Gauss-Bonnet theory of gravity suggested in [K.~Aoki, M.~Gorji and S.~Mukohyama, arXiv:2005.038...
2004.14172v2
2020-06-08
Detection and parameter estimation of binary neutron star merger remnants
Detection and parameter estimation of binary neutron star merger remnants can shed light on the physics of hot matter at supranuclear densities. Here we develop a fast, simple model that can generate gravitational waveforms, and show it can be used for both detection and parameter estimation of post-merger remnants. Th...
2006.04396v1
2020-06-10
Study of magnetic interface and its effect in Fe/NiFe bilayers of alternating order
We present a comprehensive study on the magnetization reversal in Fe/NiFe bilayer system by alternating the order of the magnetic layers. All the samples show growth-induced uniaxial magnetic anisotropy due to oblique angle deposition technique. Strong interfacial exchange coupling between the Fe and NiFe layers leads ...
2006.05756v1
2020-07-29
Dynamics of antiferromagnetic skyrmion in absence and presence of pinning defect
A theoretical study on the dynamics of an antiferromagnetic (AFM) skyrmion is indispensable for revealing the underlying physics and understanding the numerical and experimental observations. In this work, we present a reliable theoretical treatment of the spin current induced motion of an AFM skyrmion in the absence a...
2007.14562v1
2020-08-08
Axial Gravitational Waves in Bianchi I Universe
In this paper, we have studied the propagation of axial gravitational waves in Bianchi I universe using the Regge-Wheeler gauge. In this gauge, there are only two non-zero components of $ h_{\mu\nu} $ in the case of axial waves: $h_0(t,r)$ and $h_1(t,r)$. The field equations in absence of matter have been derived both ...
2008.04780v2
2020-08-15
Stability analysis of the linear discrete teleoperation systems with stochastic sampling and data dropout
This paper addresses the stability conditions of the sampled-data teleoperation systems consisting continuous time master, slave, operator, and environment with discrete time controllers over general communication networks. The output signals of the slave and master robots are quantized with stochastic sampling periods...
2008.06683v1
2020-08-25
The Sandwich Mode for Vertical Shear Instability in Protoplanetary Disks
Turbulence has a profound impact on the evolution of gas and dust in protoplanetary disks (PPDs), from driving the collisions and the diffusion of dust grains, to the concentration of pebbles in giant vortices, thus, facilitating planetesimal formation. The Vertical Shear Instability (VSI) is a hydrodynamic mechanism, ...
2008.11195v2
2020-09-07
Spin pumping in d-wave superconductor/ferromagnet hybrids
Spin-pumping across ferromagnet/superconductor (F/S) interfaces has attracted much attention lately. Yet the focus has been mainly on s-wave superconductors-based systems whereas (high-temperature) d-wave superconductors such as YBa2Cu3O7-d (YBCO) have received scarce attention despite their fundamental and technologic...
2009.03196v3
2020-09-22
Magnon-mediated spin currents in Tm3Fe5O12/Pt with perpendicular magnetic anisotropy
The control of pure spin currents carried by magnons in magnetic insulator (MI) garnet films with a robust perpendicular magnetic anisotropy (PMA) is of great interest to spintronic technology as they can be used to carry, transport and process information. Garnet films with PMA present labyrinth domain magnetic struct...
2009.10299v1
2020-09-29
The one-dimensional stochastic Keller--Segel model with time-homogeneous spatial Wiener processes
Chemotaxis is a fundamental mechanism of cells and organisms, which is responsible for attracting microbes to food, embryonic cells into developing tissues, or immune cells to infection sites. Mathematically chemotaxis is described by the Patlak--Keller--Segel model. This macroscopic system of equations is derived from...
2009.13789v1
2020-10-15
Delayed bifurcation in elastic snap-through instabilities
We study elastic snap-through induced by a control parameter that evolves dynamically. In particular, we study an elastic arch subject to an end-shortening that evolves linearly with time, i.e. at a constant rate. For large end-shortening the arch is bistable but, below a critical end-shortening, the arch becomes monos...
2010.07850v1
2020-10-29
Connecting cosmological accretion to strong Lyman-alpha absorbers
We present an analytical model for the cosmological accretion of gas onto dark matter halos, based on a similarity solution applicable to spherical systems. Performing simplified radiative transfer, we compute how the accreting gas turns increasingly neutral as it self-shields from the ionising background, and obtain t...
2010.15857v1
2020-11-25
Early modified gravity in light of the $H_0$ tension and LSS data
We present a model of Early Modified Gravity (EMG) consisting in a scalar field $\sigma$ with a non-minimal coupling to the Ricci curvature of the type $M^2_{\rm pl}+\xi \sigma^2$ plus a cosmological constant and a small effective mass and demonstrate its ability to alleviate the $H_0$ tension while providing a good fi...
2011.12934v2
2021-01-16
Excitation and evolution of coronal oscillations in self-consistent 3D radiative MHD simulations of the solar atmosphere
Solar coronal loops are commonly subject to oscillations. Observations of coronal oscillations are used to infer physical properties of the coronal plasma using coronal seismology. Excitation and evolution of oscillations in coronal loops is typically studied using highly idealised models of magnetic flux-tubes. In ord...
2101.06430v1
2021-02-17
Linear Nearest Neighbor Flocks with All Distinct Agents
This paper analyzes the global dynamics of 1-dimensional agent arrays with nearest neighbor linear couplings. The equations of motion are second order linear ODEs with constant coeffcients. The novel part of this research is that the couplings are different for each distinct agent. We allow the forces to depend on the ...
2102.09020v1
2021-03-18
The APOGEE Data Release 16 Spectral Line List
The updated H-band spectral line list (from \lambda 15,000 - 17,000\AA) adopted by the Apache Point Observatory Galactic Evolution Experiment (APOGEE) for the SDSS IV Data Release 16 (DR16) is presented here. The APOGEE line list is a combination of atomic and molecular lines with data from laboratory, theoretical, and...
2103.10112v1
2021-03-18
Soft mode theory of ferroelectric phase transitions in the low-temperature phase
Historically, the soft mode theory of ferroelectric phase transitions has been developed for the high-temperature (paraelectric) phase, where the phonon mode softens upon decreasing the temperature. In the low-temperature ferroelectric phase, a similar phonon softening occurs, also leading to a bosonic condensation of ...
2103.10262v1
2021-03-23
High-order implicit time integration scheme based on Padé expansions
A single-step high-order implicit time integration scheme for the solution of transient and wave propagation problems is presented. It is constructed from the Pad\'e expansions of the matrix exponential solution of a system of first-order ordinary differential equations formulated in the state-space. A computationally ...
2103.12282v1
2021-04-01
Brownian motion under intermittent harmonic potentials
We study the effects of an intermittent harmonic potential of strength $\mu = \mu_0 \nu$ -- that switches on and off stochastically at a constant rate $\gamma$, on an overdamped Brownian particle with damping coefficient $\nu$. This can be thought of as a realistic model for realisation of stochastic resetting. We show...
2104.00609v2
2021-05-28
Designing a Plasma Lens as a Matching Device for the ILC Positron Source
To realise a planned high-luminosity and high-energy $e^+e^-$-collider, as the ILC, a large amount of positrons have to be produced and the accelerated particles have to be captured and matched according to the damping ring acceptances. %There exist several technical possibilities. In this contribution a new promising ...
2105.14008v1
2021-07-13
Tuning the Optical Properties of an MoSe$_2$ Monolayer Using Nanoscale Plasmonic Antennas
Nanoplasmonic systems combined with optically-active two-dimensional materials provide intriguing opportunities to explore and control light-matter interactions at extreme sub-wavelength lengthscales approaching the exciton Bohr radius. Here, we present room- and cryogenic-temperature investigations of light-matter int...
2107.06410v2
2021-09-10
Electrical spectroscopy of the spin-wave dispersion and bistability in gallium-doped yttrium iron garnet
Yttrium iron garnet (YIG) is a magnetic insulator with record-low damping, allowing spin-wave transport over macroscopic distances. Doping YIG with gallium ions greatly reduces the demagnetizing field and introduces a perpendicular magnetic anisotropy, which leads to an isotropic spin-wave dispersion that facilitates s...
2109.05045v1
2021-09-17
Adaptive Steering Control for Steer-by-Wire Systems
Steer-by-Wire (SBW) systems are being adapted widely in semi-autonomous and fully autonomous vehicles. The main control challenge in a SBW system is to follow the steering commands in the face of parametric uncertainties, external disturbances and actuator delay; crucially, perturbations in inertial parameters and damp...
2109.08380v1
2021-11-04
Momentum-space decoherence of distinguishable and identical particles in the Caldeira-Leggett formalism
In this work, momentum-space decoherence using minimum and nonminimum-uncertainty-product (stretched) Gaussian wave packets in the framework of Caldeira-Leggett formalism and under the presence of a linear potential is studied. As a dimensionless measure of decoherence, purity, a quantity appearing in the definition of...
2111.03127v1
2022-01-20
Oxygen-enhanced extremely metal-poor DLAs: A signpost of the first stars?
We present precise abundance determinations of two near-pristine damped Ly$\alpha$ systems (DLAs) to assess the nature of the [O/Fe] ratio at [Fe/H] < -3 (i.e. <1/1000 of the solar metallicity). Prior observations indicate that the [O/Fe] ratio is consistent with a constant value, [O/Fe] ~ +0.4, when -3 < [Fe/H] < -2, ...
2201.08394v1
2022-02-18
Massive neutrino self-interactions with a light mediator in cosmology
Nonstandard self-interactions can alter the evolution of cosmological neutrinos, mainly by damping free streaming, which should leave traces in cosmological observables. Although overall effects are opposite to those produced by neutrino mass and a larger $N_{\rm eff}$, they cannot be totally canceled by these last. We...
2202.09310v2
2022-02-16
Egg-speriments: Stretch, crack, and spin
Eggs are key ingredients in our kitchens because of their nutritional values and functional properties such as foaming, emulsifying and gelling, offering a wide variety of culinary achievements. They also constitute ideal objects to illustrate a myriad of scientific concepts. In this article, we focus on several experi...
2202.10243v1
2022-03-15
Thermodynamic engine powered by anisotropic fluctuations
The purpose of this work is to present the concept of an autonomous Stirling-like engine powered by anisotropy of thermodynamic fluctuations. Specifically, simultaneous contact of a thermodynamic system with two heat baths along coupled degrees of freedom generates torque and circulatory currents -- an arrangement refe...
2203.07573v2
2022-03-27
Giant bulk spin-orbit torque and efficient electrical switching in single ferrimagnetic FeTb layers with strong perpendicular magnetic anisotropy
Efficient manipulation of antiferromagnetically coupled materials that are integration-friendly and have strong perpendicular magnetic anisotropy (PMA) is of great interest for low-power, fast, dense magnetic storage and computing. Here, we report a distinct, giant bulk damping-like spin-orbit torque in strong-PMA ferr...
2203.14193v1
2022-04-11
Diffusion of elastic waves in a continuum solid with a random array of pinned dislocations
The propagation of incoherent elastic energy in a three-dimensional solid due to the scattering by many, randomly placed and oriented, pinned dislocation segments, is considered in a continuum mechanics framework. The scattering mechanism is that of an elastic string of length L that re-radiates as a response to an inc...
2204.05140v1
2022-04-17
Dynamics of co-orbital exoplanets in a first order resonance chain with tidal dissipation
Co-orbital planets (in a $1:1$ mean motion resonance) can be formed within a Laplace resonance chain. Here, we develop a secular model to study the dynamics of the resonance chain $p:p:p+1$, where the co-orbital pair is in a first-order mean motion resonance with the outermost third planet. Our model takes into account...
2204.08074v1
2022-04-26
Quintom fields from chiral K-essence cosmology
In this paper, we present an analysis of a chiral cosmological scenario from the perspective of K-essence formalism. In this setup, several scalar fields interact within the kinetic and potential sectors. However, we only consider a flat Friedmann--Robertson--Lama\^{\i}tre--Walker universe coupled minimally to two quin...
2204.12083v2