385 research outputs found
Thermal and Dynamical Particle Creation in a Curved Geometry
A generalization of ``Termo Field Dynamics'' to a curved geometry is
proposed. In particular a neutral scalar field minimally coupled to gravity is
considered as matter content in a Robertson-Walker metric. A non linear
amplification in the particle creation is obtained, due to the altogether
action of thermal and geometric effects. As a consequence the frequencies in
the system look like red shifted with respect to the case where the thermal
creation is not taken into account.Comment: 13 page
Vacuum structure for expanding geometry
We consider gravitational wave modes in the FRW metrics in a de Sitter phase
and show that the state space splits into many unitarily inequivalent
representations of the canonical commutation relations. Non-unitary time
evolution is described as a trajectory in the space of the representations. The
generator of time evolution is related to the entropy operator. The
thermodynamic arrow of time is shown to point in the same direction of the
cosmological arrow of time. The vacuum is a two-mode SU(1,1) squeezed state of
thermo field dynamics. The link between expanding geometry, squeezing and
thermal properties is exhibited.Comment: Latex file, epsfig, 1 figure, 21 page
Projective Invariance and One-Loop Effective Action in Affine-Metric Gravity Interacting with Scalar Field
We investigate the influence of the projective invariance on the
renormalization properties of the theory. One-loop counterterms are calculated
in the most general case of interaction of gravity with scalar field.Comment: 10 pages, LATE
A Conformal Affine Toda Model of 2D-Black Holes the End-Point State and the S-Matrix
In this paper we investigate in more detail our previous formulation of the
dilaton-gravity theory by Bilal--Callan--de~Alwis as a -conformal affine
Toda (CAT) theory. Our main results are: i) a field redefinition of the
CAT-basis in terms of which it is possible to get the black hole solutions
already known in the literature; ii) an investigation the scattering matrix
problem for the quantum black hole states. It turns out that there is a range
of values of the free-falling shock matter fields forming the black hole
solution, in which the end-point state of the black hole evaporation is a zero
temperature regular remnant geometry. It seems that the quantum evolution to
this final state is non-unitary, in agreement with Hawking's scenario for the
black hole evaporation.Comment: ROM2F-93-03, 27 pages, phyzz
Yang-Mills Theory as a Deformation of Topological Field Theory, Dimensional Reduction and Quark Confinement
We propose a reformulation of Yang-Mills theory as a perturbative deformation
of a novel topological (quantum) field theory. We prove that this reformulation
of the four-dimensional QCD leads to quark confinement in the sense of area law
of the Wilson loop. First, Yang-Mills theory with a non-Abelian gauge group G
is reformulated as a deformation of a novel topological field theory. Next, a
special class of topological field theories is defined by both BRST and
anti-BRST exact action corresponding to the maximal Abelian gauge leaving the
maximal torus group H of G invariant. Then we find the topological field theory
() has a hidden supersymmetry for a choice of maximal Abelian gauge. As a
result, the D-dimensional topological field theory is equivalent to the
(D-2)-dimensional coset G/H non-linear sigma model in the sense of Parisi and
Sourlas dimensional reduction. After maximal Abelian gauge fixing, the
topological property of magnetic monopole and anti-monopole of four-dimensional
Yang-Mills theory is translated into that of instanton and anti-instanton in
two-dimensional equivalent model. It is shown that the linear static potential
in four-dimensions follows from the instanton--anti-instanton gas in the
equivalent two-dimensional non-linear sigma model obtained from the
four-dimensional topological field theory by dimensional reduction, while the
remaining Coulomb potential comes from the perturbative part in
four-dimensional Yang-Mills theory. The dimensional reduction opens a path for
applying various exact methods developed in two-dimensional quantum field
theory to study the non-perturbative problem in low-energy physics of
four-dimensional quantum field theories.Comment: 58 pages, Latex, no figures, version accepted for publication in
Phys. Rev. D (additions of Discussion, references and minor changes
Challenges of beta-deformation
A brief review of problems, arising in the study of the beta-deformation,
also known as "refinement", which appears as a central difficult element in a
number of related modern subjects: beta \neq 1 is responsible for deviation
from free fermions in 2d conformal theories, from symmetric omega-backgrounds
with epsilon_2 = - epsilon_1 in instanton sums in 4d SYM theories, from
eigenvalue matrix models to beta-ensembles, from HOMFLY to super-polynomials in
Chern-Simons theory, from quantum groups to elliptic and hyperbolic algebras
etc. The main attention is paid to the context of AGT relation and its possible
generalizations.Comment: 20 page
Holographic Derivation of Kerr-Newman Scattering Amplitudes for General Charge and Spin
Near-superradiant scattering of charged scalars and fermions by a
near-extreme Kerr-Newman black hole and photons and gravitons by a near-extreme
Kerr black hole are computed as certain Fourier transforms of correlators in a
two-dimensional conformal field theory. The results agree with the classic
spacetime calculations from the 1970s, thereby providing good evidence for a
conjectured Kerr-Newman/CFT correspondence.Comment: 22 page
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