116 research outputs found
Hawking Radiation, Covariant Boundary Conditions and Vacuum States
The basic characteristics of the covariant chiral current are obtained from a
chiral effective action. These results are used to justify the covariant
boundary condition used in recent approaches
\cite{Isowilczek,Isoumtwilczek,shailesh,shailesh2,Banerjee} of computing the
Hawking flux from chiral gauge and gravitational anomalies. We also discuss a
connection of our results with the conventional calculation of nonchiral
currents and stress tensors in different (Unruh, Hartle-Hawking and Boulware)
states.Comment: 18 pages, no figures, minor changes, to appear in Phys. Rev.
Hawking Radiation and Covariant Anomalies
Generalising the method of Wilczek and collaborators we provide a derivation
of Hawking radiation from charged black holes using only covariant gauge and
gravitational anomalies. The reliability and universality of the anomaly
cancellation approach to Hawking radiation is also discussed.Comment: Minor changes, conforms to published versio
Remarks on the Generalized Chaplygin Gas
We have developed an action formulation for the Generalized Chaplygin Gas
(GCG). The most general form for the nonrelativistic GCG action is derived
consistent with the equation of state. We have also discussed a relativistic
formulation for GCG by providing a detailed analysis of the Poincare algebra.Comment: References addede
Aspects of Diffeomorphism and Conformal invariance in classical Liouville theory
The interplay between the diffeomorphism and conformal symmetries (a feature
common in quantum field theories) is shown to be exhibited for the case of
black holes in two dimensional classical Liouville theory. We show that
although the theory is conformally invariant in the near horizon limit, there
is a breaking of the diffeomorphism symmetry at the classical level. On the
other hand, in the region away from the horizon, the conformal symmetry of the
theory gets broken with the diffeomorphism symmetry remaining intact.Comment: Accepted in Euro. Phys. Letters., Title changed, abstract modified,
major modifications made in the pape
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