1,214 research outputs found
Counting Photons in Static Electric and Magnetic Fields
We describe the electromagnetic field by the massless limit of a massive
vector field in the presence of a Coulomb gauge fixing term. The gauge fixing
term ensures that, in the massless limit, the longitudinal mode is removed from
the spectrum and only the two transverse modes survive. The system, coupled to
a classical conserved current, is quantized in the canonical formalism. The
classical field configurations due to time-independent electric charges and
currents are represented by coherent states of longitudinal and transverse
photons, respectively. The occupation number in these states is finite. In
particular, the number of longitudinal photons bound by an electric charge q is
given by N=q^2/(16\pi\hbar).Comment: 11 pages, version to appear in EPJ
On the Phase Transition of Conformal Field Theories with Holographic Duals
We study the thermodynamic relations of conformal field theories (CFTs),
which are holographically dual to anti-de Sitter-Schwarzschild bulk
space-times. A Cardy-Verlinde formula is derived thermodynamically for CFTs
living on S^n x R with S^n having an arbitrary radius. The Hawking-Page phase
transition of the CFT is described using Landau's theory of phase transitions,
and an alternative derivation of the Cardy-Verlinde formula is presented. The
condensate in the high temperature phase is identified as being composed of
radiational matter.Comment: 10 pages, final version to appear on PL
A Regularization Scheme for the AdS/CFT Correspondence
The prescription of the AdS/CFT correspondence is refined by using a
regularization procedure, which makes is possible to calculate the divergent
local terms in the CFT two-point function. We present the procedure for the
example of the scalar field.Comment: 5 pages, uses amsmath, amssymb packages, v2: 2 references adde
Holographic Renormalisation and Anomalies
The Weyl anomaly in the Holographic Renormalisation Group as implemented
using Hamilton-Jacobi language is studied in detail. We investigate the
breakdown of the descent equations in order to isolate the Weyl anomaly of the
dual field theory close to the (UV) fixed point. We use the freedom of adding
finite terms to the renormalised effective action in order to bring the
anomalies in the expected form. We comment on different ways of describing the
bare and renormalised schemes, and on possible interpretations of the descent
equations as describing the renormalisation group flow non-perturbatively. We
find that under suitable assumptions these relations may lead to a class of
c-functions.Comment: 17 page
Theory of Non-Equilibrium Sationary States as a Theory of Resonances
We study a small quantum system (e.g. a simplified model for an atom or
molecule) interacting with two bosonic or fermionic reservoirs (say, photon or
phonon fields). We show that the combined system has a family of stationary
states, parametrized by two numbers , (``reservoir temperatures'').
If , then these states are non-equilibrium, stationary states
(NESS). In the latter case we show that they have nonvanishing heat fluxes and
positive entropy production. Furthermore, we show that these states are
dynamically asymptotically stable. The latter means that the evolution with an
initial condition, normal with respect to any state where the reservoirs are in
equilibria at temperatures and , converges to the corresponding
NESS. Our results are valid for the temperatures satisfying the bound
, where is the coupling constant and is a power related to the infra-red behaviour of the coupling
functions.Comment: 1 figure. To appear in Ann. H. Poincar
AdS_3/CFT_2 correspondence at finite temperature
The AdS/CFT correspondence is established for the AdS_3 space compactified on
a solid torus with the CFT field on the boundary. Correlation functions that
correspond to the bulk theory at finite temperature are obtained in the
regularization a'la Gubser, Klebanov, and Polyakov. The BTZ black hole
solutions in AdS_3 are T-dual to the solution in the AdS_3 space without
singularity.Comment: 9pp., LaTe
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