Hawking Radiation, Covariant Boundary Conditions and Vacuum States

The basic characteristics of the covariant chiral current $$and the covariant chiral energy-momentum tensor$$ 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

Statistical Origin of Gravity

Starting from the definition of entropy used in statistical mechanics we show that it is proportional to the gravity action. For a stationary black hole this entropy is expressed as $S = E/ 2T$, where $T$ is the Hawking temperature and $E$ is shown to be the Komar energy. This relation is also compatible with the generalised Smarr formula for mass.Comment: LaTex, 7 pages, no figure, minor clarifications, references added, to appear in Phys. Rev.

Connecting anomaly and tunneling methods for Hawking effect through chirality

The role of chirality is discussed in unifying the anomaly and the tunneling formalisms for deriving the Hawking effect. Using the chirality condition and starting from the familiar form of the trace anomaly, the chiral (gravitational) anomaly, manifested as a nonconservation of the stress tensor, near the horizon of a black hole, is derived. Solution of this equation yields the stress tensor whose asymptotic infinity limit gives the Hawking flux. Finally, use of the same chirality condition in the tunneling formalism gives the Hawking temperature that is compatible with the flux obtained by anomaly method.Comment: LaTex, 8 pages, no figures, reformulation of tunneling mechanism, to appear in Phys. Rev.

A Canonical Approach to the Quantization of the Damped Harmonic Oscillator

We provide a new canonical approach for studying the quantum mechanical damped harmonic oscillator based on the doubling of degrees of freedom approach. Explicit expressions for Lagrangians of the elementary modes of the problem, characterising both forward and backward time propagations are given. A Hamiltonian analysis, showing the equivalence with the Lagrangian approach, is also done. Based on this Hamiltonian analysis, the quantization of the model is discussed.Comment: Revtex, 6 pages, considerably expanded with modified title and refs.; To appear in J.Phys.