63,659 research outputs found
Comment on ``Quantum Phase of Induced Dipoles Moving in a Magnetic Field''
It has recently been suggested that an Aharonov-Bohm phase should be capable
of detection using beams of neutral polarizable particles. A more careful
analysis of the proposed experiment suffices to show, however, that it cannot
be performed regardless of the strength of the external electric and magnetic
fields.Comment: 2 pages, latex file, no figure
Quantization of Gauge Field Theories on the Front-Form without Gauge Constraints I : The Abelian Case
Recently, we have proposed a new front-form quantization which treated both
the and the coordinates as front-form 'times.' This
quantization was found to preserve parity explicitly. In this paper we extend
this construction to local Abelian gauge fields . We quantize this theory using
a method proposed originally by Faddeev and Jackiw . We emphasize here the
feature that quantizing along both and , gauge theories does not
require extra constraints (also known as 'gauge conditions') to determine the
solution uniquely.Comment: 18 pages, phyzz
Functional Forms for the Squeeze and the Time-Displacement Operators
Using Baker-Campbell-Hausdorff relations, the squeeze and harmonic-oscillator
time-displacement operators are given in the form , where ,
, , and are explicitly determined. Applications are
discussed.Comment: 10 pages, LaTe
Transition from quintessence to phantom phase in quintom model
Assuming the Hubble parameter is a continuous and differentiable function of
comoving time, we investigate necessary conditions for quintessence to phantom
phase transition in quintom model. For power-law and exponential potential
examples, we study the behavior of dynamical dark energy fields and Hubble
parameter near the transition time, and show that the phantom-divide-line w=-1
is crossed in these models.Comment: LaTeX, 19 pages, four figures, some minor changes in Introduction,
two figures added and the references updated, accepted for publication in
Phys. Rev.
Cosmological Models and Latest Observational Data
In this note, we consider the observational constraints on some cosmological
models by using the 307 Union type Ia supernovae (SNIa), the 32 calibrated
Gamma-Ray Bursts (GRBs) at , the updated shift parameter from WMAP
5-year data (WMAP5), and the distance parameter of the measurement of the
baryon acoustic oscillation (BAO) peak in the distribution of SDSS luminous red
galaxies with the updated scalar spectral index from WMAP5. The tighter
constraints obtained here update the ones obtained previously in the
literature.Comment: 10 pages, 5 figures, 1 table, revtex4; v2: discussions added,
accepted by Eur. Phys. J. C; v3: published versio
Critical phenomena and thermodynamic geometry of charged Gauss-Bonnet AdS black holes
In this paper, we study the phase structure and equilibrium state space
geometry of charged topological Gauss-Bonnet black holes in -dimensional
anti-de Sitter spacetime. Several critical points are obtained in the canonical
ensemble, and the critical phenomena and critical exponents near them are
examined. We find that the phase structures and critical phenomena drastically
depend on the cosmological constant and dimensionality . The
result also shows that there exists an analogy between the black hole and the
van der Waals liquid gas system. Moreover, we explore the phase transition and
possible property of the microstructure using the state space geometry. It is
found that the Ruppeiner curvature diverges exactly at the points where the
heat capacity at constant charge of the black hole diverges. This black hole is
also found to be a multiple system, i.e., it is similar to the ideal gas of
fermions in some range of the parameters, while to the ideal gas of bosons in
another range.Comment: 17 pages, 8 figures, 3 table
Probing the plateau-insulator quantum phase transition in the quantum Hall regime
We report quantum Hall experiments on the plateau-insulator transition in a
low mobility In_{.53} Ga_{.47} As/InP heterostructure. The data for the
longitudinal resistance \rho_{xx} follow an exponential law and we extract a
critical exponent \kappa= .55 \pm .05 which is slightly different from the
established value \kappa = .42 \pm .04 for the plateau transitions. Upon
correction for inhomogeneity effects, which cause the critical conductance
\sigma_{xx}^* to depend marginally on temperature, our data indicate that the
plateau-plateau and plateau- insulator transitions are in the same universality
class.Comment: 4 pages, 4 figures (.eps
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