8,975 research outputs found
Near-horizon modes and self-adjoint extensions of the Schroedinger operator
We investigate the dynamics of scalar fields in the near-horizon exterior
region of a Schwarzschild black hole. We show that low-energy modes are
typically long-living and might be considered as being confined near the black
hole horizon. Such dynamics are effectively governed by a Schroedinger operator
with infinitely many self-adjoint extensions parameterized by , a
situation closely resembling the case of an ordinary free particle moving on a
semiaxis. Even though these different self-adjoint extensions lead to
equivalent scattering and thermal processes, a comparison with a simplified
model suggests a physical prescription to chose the pertinent self-adjoint
extensions. However, since all extensions are in principle physically
equivalent, they might be considered in equal footing for statistical analyses
of near-horizon modes around black holes. Analogous results hold for any
non-extremal, spherically symmetric, asymptotically flat black hole.Comment: 10 pages, 1 fig, contribution submitted to the volume "Classical and
Quantum Physics: Geometry, Dynamics and Control. (60 Years Alberto Ibort
Fest)" Springer (2018
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
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