20,853 research outputs found
Extensions of Stern's congruence for Euler numbers
For a nonzero integer let be given by
,
where is the greatest integer not exceeding . As is
the Euler number, can be viewed as a generalization of Euler
numbers. Let and be positive integers, and let be a nonnegative
integer. In this paper, we determine modulo for
. For we also establish congruences for
and
where , and is Euler's
function.Comment: 16 page
Blowing Polar Skyrmion Bubbles in Oxide Superlattices
Particle-like topological structures such as skyrmions and vortices have
garnered ever-increasing interests due to the rich physical insights and
potential broad applications. Here we discover the reversible switching between
polar skyrmion bubbles and ordered vortex arrays in ferroelectric superlattices
under an electric field, reminiscent of the Plateau-Raleigh instability in
fluid mechanics. Electric field phase diagram is constructed, showing wide
stability window for the observed polar skyrmions. This study is a
demonstration for the computational design of ferroelectric topological
structures and field-induced topological phase transitions.Comment: 16 Pages 4 figure
Strong CP Problem, Neutrino Masses and the 750 GeV Diphoton Resonance
We present an left-right symmetric model with a discrete
parity symmetry to realize a universal seesaw scenario. The model can
simultaneously solve the strong CP problem without resorting to the unobserved
axion and explain the 750 GeV diphoton resonance reported recently by the ATLAS
and CMS collaborations at the LHC. Owing to large suppressions in the two-loop
induced Dirac mass terms, the Majorana mass matrices of left- and right-handed
neutrinos naturally share the same structure. That allows us to quantitatively
study the neutrinoless double beta decay induced by the right-handed currents
Quantum particle confined to a thin-layer volume: Non-uniform convergence toward the curved surface
We clearly refine the fundamental framework of the thin-layer quantization
procedure, and further develop the procedure by taking the proper terms of
degree one in ( denotes the curvilinear coordinate variable
perpendicular to curved surface) back into the surface quantum equation. The
well-known geometric potential and kinetic term are modified by the surface
thickness. Applying the developed formalism to a toroidal system obtains the
modification for the kinetic term and the modified geometric potential
including the influence of the surface thickness.Comment: 9 pages, 3 figure
Algebraic Characterizations of Consensus Problems for Networked Dynamic Systems
In this paper, we study the consensus problem for networked dynamic systems
with arbitrary initial states, and present some structural characterization and
direct construction of consensus functions. For the consensus problem under
similar transformation, we establish some necessary and sufficient conditions
by exploiting the structure of consensus functions. Finally, we discuss the
consensus problem for dynamic systems under switching by using the common
Lyapunov function method
Unsupervised Manifold Clustering of Topological Phononics
Classification of topological phononics is challenging due to the lack of
universal topological invariants and the randomness of structure patterns.
Here, we show the unsupervised manifold learning for clustering topological
phononics without any priori knowledge, neither topological invariants nor
supervised trainings, even when systems are imperfect or disordered. This is
achieved by exploiting the real-space projection operator about finite phononic
lattices to describe the correlation between oscillators. We exemplify the
efficient unsupervised manifold clustering in typical phononic systems,
including one-dimensional Su-Schrieffer-Heeger-type phononic chain with random
couplings, amorphous phononic topological insulators, higher-order phononic
topological states and non-Hermitian phononic chain with random dissipations.
The results would inspire more efforts on applications of unsupervised machine
learning for topological phononic devices and beyond.Comment: 6 pages, 4 figure
Infinitely many small energy solutions of a semilinear Schrodinger equation
In this paper we prove the existence of infinitely many small energy solution
of a semilinear Schrodinger equation via the dual form of the generalized
fountain theorem. This equation is with periodic potential and concave-convex
nonlinearities.Comment: 15 page
A two-level atom coupled to a controllable squeezed vacuum field reservoir
The dissipative and decoherence properties of the two-level atom interacting
with the squeezed vacuum field reservoir are investigated based on the
nonautonomous master equation of the atomic density matrix in the framework of
algebraic dynamics. The nonautonomous master equation is converted into a
Schr\"{o}dinger-like equations and its dynamical symmetry is found based on the
left and right representations of the relevant algebra. The time-dependent
solution and the steady solution are obtained analytically. The asymptotic
behavior of the solution is examined and the approach to the equilibrium state
is proved. Based on the analytic solution the response of the system to the
squeezed vacuum field reservoir is studied numerically.Comment: 8 pages, 6 figure
Effect of stochastic grain heating on cold dense clouds chemistry
The temperatures of dust grains play important roles in the chemical
evolution of molecular clouds. Unlike large grains, the temperature
fluctuations of small grains induced by photons may be significant. Therefore,
if the grain size distribution is included in astrochemical models, the
temperatures of small dust grains may not be assumed to be constant. We
simulate a full gas-grain reaction network with a set of dust grain radii using
the classical MRN grain size distribution and include the temperature
fluctuations of small dust grains. Monte Carlo method is used to simulate the
real-time dust grain's temperature fluctuations which is caused by the external
low energy photons and the internal cosmic ray induced secondary photons. The
increase of dust grains radii as ice mantles accumulate on grain surfaces is
also included in our models. We found that surface CO abundances in models
with grain size distribution and temperature fluctuations are more than one
order of magnitude larger than those with single grain size. Small amounts of
terrestrial complex organic molecules (COMs) can also be formed on small grains
due to the temperature spikes induced by external low energy photons. However,
cosmic ray induced secondary photons overheat small grains so that surface CO
sublime and less radicals are formed on grains surfaces, thus the production of
surface CO and COMs decreases by about one order of magnitude. The
overheating of small grains can be offset by grain growth so that the formation
of surface CO and COMs becomes more efficient.Comment: 16 pages, 10 figures, accepted for publication in MNRA
Probing Higgs Width and Top Quark Yukawa Coupling from and Productions
We demonstrate that four top-quark production is a powerful tool to constrain
the top Yukawa coupling. The constraint is robust in the sense that it does not
rely on the Higgs boson decay. Taking into account the projection of the
production by the ATLAS collaobration, we obtain a bound on Higgs
boson width, , at the 14 TeV LHC with an
integrated luminosity of . Increasing the luminosity to
yields
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