125,895 research outputs found
Calculation of Elastic Green's Functions for Lattices with Cavities
In this Brief Report, we present an algorithm for calculating the elastic
Lattice Greens Function of a regular lattice, in which defects are created by
removing lattice points. The method is computationally efficient, since the
required matrix operations are on matrices that scale with the size of the
defect subspace, and not with the size of the full lattice. This method allows
the treatment of force fields with multi-atom interactions.Comment: 3 pages. RevTeX, using epsfig.sty. One figur
Critical domain-wall dynamics of model B
With Monte Carlo methods, we simulate the critical domain-wall dynamics of
model B, taking the two-dimensional Ising model as an example. In the
macroscopic short-time regime, a dynamic scaling form is revealed. Due to the
existence of the quasi-random walkers, the magnetization shows intrinsic
dependence on the lattice size . A new exponent which governs the
-dependence of the magnetization is measured to be .Comment: 10pages, 4 figure
Understanding and Improving the Wang-Landau Algorithm
We present a mathematical analysis of the Wang-Landau algorithm, prove its
convergence, identify sources of errors and strategies for optimization. In
particular, we found the histogram increases uniformly with small fluctuation
after a stage of initial accumulation, and the statistical error is found to
scale as with the modification factor . This has implications
for strategies for obtaining fast convergence.Comment: 4 pages, 2 figures, to appear in Phys. Rev.
Cavity-QED with cold atoms trapped in a double-well potential
We investigate the interplay dynamics of a cavity qed system, where the
two-level atoms are trapped in a double-well potential, and the cavity mode,
with a frequency largely detuned to the atomic level splitting, is driven by a
probe laser. The interaction between the center-of-mass motion of the atoms and
the cavity mode is induced by the position dependent atom-field coupling. The
dynamics of the system is characterized by two distinct time scales, the
inverse of the atomic interwell tunneling rate and the inverse of the cavity
loss rate. The system shows drastically different (quasi) steady behaviors in
the short-time and long-time intervals.Comment: 8 pages, 5 figue
Unstable particle's wave-function renormalization prescription
We strictly define two set Wave-function Renormalization Constants (WRC)
under the LSZ reduction formula for unstable particles at the first time. Then
by introducing antiparticle's WRC and the CPT conservation law we obtain a new
wave-function renormalization condition which can be used to totally determine
the two set WRC. We calculate two physical processes to manifest the
consistence of the present wave-function renormalization prescription with the
gauge theory in standard model. We also prove that the conventional
wave-function renormalization prescription which discards the imaginary part of
unstable particle's WRC leads to physical amplitude gauge dependent.Comment: 10 pages, 3 figure
Search for a circum-planetary material and orbital period variations of short-period Kepler exoplanet candidates
A unique short-period Mercury-size Kepler exoplanet candidate KIC012557548b
has been discovered recently by Rappaport et al. (2012). This object is a
transiting disintegrating exoplanet with a circum-planetary material -
comet-like tail. Close-in exoplanets, like KIC012557548b, are subjected to the
greatest planet-star interactions. This interaction may have various forms. In
certain cases it may cause formation of the comet-like tail. Strong interaction
with the host star, and/or presence of an additional planet may lead to
variations in the orbital period of the planet. Our main aim is to search for
comet-like tails similar to KIC012557548b and for long-term orbital period
variations. We are curious about frequency of comet-like tail formation among
short-period Kepler exoplanet candidates. We concentrate on a sample of 20
close-in candidates with a period similar to KIC012557548b from the Kepler
mission.Comment: 19 pages, 75 figures, AN accepte
Creep motion of a domain wall in the two-dimensional random-field Ising model with a driving field
With Monte Carlo simulations, we study the creep motion of a domain wall in
the two-dimensional random-field Ising model with a driving field. We observe
the nonlinear fieldvelocity relation, and determine the creep exponent {\mu}.
To further investigate the universality class of the creep motion, we also
measure the roughness exponent {\zeta} and energy barrier exponent {\psi} from
the zero-field relaxation process. We find that all the exponents depend on the
strength of disorder.Comment: 5 pages, 4 figure
Precise dispersive data analysis of the f0(600) pole
We review how the use of recent precise data on kaon decays together with
forward dispersion relations (FDR) and Roy's equations allow us to determine
the sigma resonance pole position very precisely, by using only experimental
input. In addition, we present preliminary results for a modified set of
Roy-like equations with only one subtraction, that show a remarkable
improvement in the precision around the sigma region. We also improve the
matching between the parametrizations at low and intermediate energy of the S0
wave, and show that the effect of this on the sigma pole position is
negligible.Comment: 4 pages, 1 figure. To appear in the proceedings of the Meson 2008
conference, June 6-10, Cracow, Polan
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