7,329 research outputs found
Domain wall theory and non-stationarity in driven flow with exclusion
We study the dynamical evolution toward steady state of the stochastic
non-equilibrium model known as totally asymmetric simple exclusion process, in
both uniform and non-uniform (staggered) one-dimensional systems with open
boundaries. Domain-wall theory and numerical simulations are used and, where
pertinent, their results are compared to existing mean-field predictions and
exact solutions where available. For uniform chains we find that the inclusion
of fluctuations inherent to the domain-wall formulation plays a crucial role in
providing good agreement with simulations, which is severely lacking in the
corresponding mean-field predictions. For alternating-bond chains the
domain-wall predictions for the features of the phase diagram in the parameter
space of injection and ejection rates turn out to be realized only in an
incipient and quantitatively approximate way. Nevertheless, significant
quantitative agreement can be found between several additional domain-wall
theory predictions and numerics.Comment: 12 pages, 12 figures (published version
Correlation--function distributions at the Nishimori point of two-dimensional Ising spin glasses
The multicritical behavior at the Nishimori point of two-dimensional Ising
spin glasses is investigated by using numerical transfer-matrix methods to
calculate probability distributions and associated moments of spin-spin
correlation functions on strips. The angular dependence of the shape of
correlation function distributions provides a stringent test of how well
they obey predictions of conformal invariance; and an even symmetry of reflects the consequences of the Ising spin-glass gauge (Nishimori)
symmetry. We show that conformal invariance is obeyed in its strictest form,
and the associated scaling of the moments of the distribution is examined, in
order to assess the validity of a recent conjecture on the exact localization
of the Nishimori point. Power law divergences of are observed near C=1
and C=0, in partial accord with a simple scaling scheme which preserves the
gauge symmetry.Comment: Final version to be published in Phys Rev
Spontaneous Breaking of Lorentz Symmetry and Vertex Operators for Vortices
We first review the spontaneous Lorentz symmetry breaking in the presence of
massless gauge fields and infraparticles. This result was obtained long time
ago in the context of rigorious quantum field theory by Frohlich et. al. and
reformulated by Balachandran and Vaidya using the notion of superselection
sectors and direction-dependent test functions at spatial infinity for the
non-local observables. Inspired by these developments and under the assumption
that the spectrum of the electric charge is quantized, (in units of a
fundamental charge e) we construct a family of vertex operators which create
winding number k, electrically charged Abelian vortices from the vacuum (zero
winding number sector) and/or shift the winding number by k units. In
particular, we find that for rotating vortices the vertex operator at level k
shifts the angular momentum of the vortex by k \frac{{\tilde q}}{q}, where
\tilde q is the electric charge of the quantum state of the vortex and q is the
charge of the vortex scalar field under the U(1) gauge field. We also show
that, for charged-particle-vortex composites angular momentum eigenvalues shift
by k \frac{{\tilde q}}{q}, {\tilde q} being the electric charge of the
charged-particle-vortex composite. This leads to the result that for
\frac{{\tilde q}}{q} half-odd integral and for odd k our vertex operators flip
the statistics of charged-particle-vortex composites from bosons to fermions
and vice versa. For fractional values of \frac{{\tilde q}}{q}, application of
vertex operator on charged-particle-vortex composite leads in general to
composites with anyonic statistics.Comment: Published version, 15+1 pages, 1 figur
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