200,251 research outputs found
Light and Airy: a simple solution for relativistic quantum acceleration radiation
We study the quantum radiation of particle production by vacuum from an
ultra-relativistic moving mirror (dynamical Casimir effect) solution that
allows (possibly for the first time) analytically calculable time evolution of
particle creation and an Airy particle spectral distribution. The reality of
the beta Bogoliubov coefficients is responsible for the simplicity, and the
mirror is asymptotically inertial at the speed of light, with finite energy
production. We also discuss general relations regarding negative energy flux,
the transformation to the 1-D Schr{\"o}dinger equation, and the incompleteness
of entanglement entropy.Comment: 10 pages, 9 figure
Dynamical Moving Mirrors and Black Holes
A simple quantum mechanical model of free scalar fields interacting with
a dynamical moving mirror is formulated and shown to be equivalent to
two-dimensional dilaton gravity. We derive the semi-classical dynamics of this
system, by including the back reaction due to the quantum radiation. We develop
a hamiltonian formalism that describes the time evolution as seen by an
asymptotic observer, and write a scattering equation that relates the
in-falling and out-going modes at low energies. At higher incoming energy flux,
however, the classical matter-mirror dynamics becomes unstable and the mirror
runs off to infinity. This instability provides a useful paradigm for black
hole formation and introduces an analogous information paradox. Finally, we
propose a new possible mechanism for restoring the stability in the
super-critical situation, while preserving quantum coherence. This mechanism is
based on the notion of an effective time evolution, that takes into account the
quantum mechanical effect of the measurement of the Hawking radiation on the
state of the infalling matter.Comment: 37 pages, 5 figures attached, epsf, harvmac, PUPT-143
Instability of hyper-compact Kerr-like objects
Viable alternatives to astrophysical black holes include hyper-compact
objects without horizon, such as gravastars, boson stars, wormholes and
superspinars. The authors have recently shown that typical rapidly-spinning
gravastars and boson stars develop a strong instability. That analysis is
extended in this paper to a wide class of horizonless objects with approximate
Kerr-like geometry. A detailed investigation of wormholes and superspinars is
presented, using plausible models and mirror boundary conditions at the
surface. Like gravastars and boson stars, these objects are unstable with very
short instability timescales. This result strengthens previous conclusions that
observed hyper-compact astrophysical objects with large rotation are likely to
be black holes.Comment: 15 pages, 3 figures. To be published in CQ
The deformed Hermitian-Yang-Mills equation in geometry and physics
We provide an introduction to the mathematics and physics of the deformed
Hermitian-Yang-Mills equation, a fully nonlinear geometric PDE on Kahler
manifolds which plays an important role in mirror symmetry. We discuss the
physical origin of the equation, and some recent progress towards its solution.
In dimension 3 we prove a new Chern number inequality and discuss the
relationship with algebraic stability conditions.Comment: 20 page
G-structures and Domain Walls in Heterotic Theories
We consider heterotic string solutions based on a warped product of a
four-dimensional domain wall and a six-dimensional internal manifold,
preserving two supercharges. The constraints on the internal manifolds with
SU(3) structure are derived. They are found to be generalized half-flat
manifolds with a particular pattern of torsion classes and they include
half-flat manifolds and Strominger's complex non-Kahler manifolds as special
cases. We also verify that previous heterotic compactifications on half-flat
mirror manifolds are based on this class of solutions.Comment: 29 pages, reference added, typos correcte
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