Shailesh Kulkarni

Hawking radiation and covariant anomalies

Generalizing 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.

Quasilocal conserved charges in a covariant theory of gravity.

In any generally covariant theory of gravity, we show the relationship between the linearized asymptotically conserved current and its nonlinear completion through the identically conserved current. Our formulation for conserved charges is based on the Lagrangian description, and so completely covariant. By using this result, we give a prescription to define quasilocal conserved charges in any higher derivative gravity. As applications of our approach, we demonstrate the angular momentum invariance along the radial direction of black holes and reproduce more efficiently the linearized potential on the asymptotic anti-de Sitter space.

Quasilocal conserved charges in the presence of a gravitational Chern-Simons term

We extend our recent work on the quasilocal formulation of conserved charges to a theory of gravity containing a gravitational Chern-Simons term. As an application of our formulation, we compute the off-shell potential and quasilocal conserved charges of some black holes in three-dimensional topologically massive gravity. Our formulation for conserved charges reproduces very effectively the well-known expressions on conserved charges and the entropy expression of black holes in the topologically massive gravity.

Hawking radiation from Garfinkle-Horowitz-Strominger and nonextremal D1-D5 black holes via covariant anomalies

We apply the method of Banerjee and Kulkarni (arXiv:0707.2449, [hep-th]) to provide a derivation of Hawking radiation from the GHS (stringy) blackhole which falls in the class of the most general spherically symmetric blackholes ( √−g 6= 1) and also the non-extremal D1−D5 blackhole using only covariant gravitational anomalies.

Deformed symmetry in Snyder space and relativistic particle dynamics

We describe the deformed Poincare-conformal symmetries implying the covariance of the noncommutative space obeying Snyders algebra. Relativistic particle models invariant under these deformed symmetries are presented. A gauge (reparametrisation) independent derivation of Snyders algebra from such models is given. The algebraic transformations relating the deformed symmetries with the usual (undeformed) ones are provided. Finally, an alternative form of an action yielding Snyders algebra is discussed where the mass of a relativistic particle gets identified with the inverse of the noncommutativity parameter.

Hawking fluxes, back reaction and covariant anomalies

Starting from the chiral covariant effective action approach of Banerjee and Kulkarni (2008 Phys. Lett. B 659 827), we provide a derivation of the Hawking radiation from a charged black hole in the presence of gravitational back reaction. The modified expressions for charge and energy flux, due to the effect of one-loop back reaction are obtained.

Remarks on the generalized Chaplygin gas

We develop 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 also discuss a relativistic formulation for GCG by providing a detailed analysis of the Poincare algebra.

Modified dispersion relations and the response of the rotating Unruh-DeWitt detector

We study the response of a rotating monopole detector that is coupled to a massless scalar field which is described by a nonlinear dispersion relation in flat spacetime. Since it does not seem to be possible to evaluate the response of the rotating detector analytically, we resort to numerical computations. Interestingly, unlike the case of the uniformly accelerated detector that has been considered recently, we find that defining the transition probability rate of the rotating detector poses no difficulties. Further, we show that the response of the rotating detector can be computed exactly (albeit, numerically) even when it is coupled to a field that is governed by a nonlinear dispersion relation. We also discuss the response of the rotating detector in the presence of a cylindrical boundary on which the scalar field is constrained to vanish. While superluminal dispersion relations hardly affect the standard results, we find that subluminal dispersion relations can lead to relatively large modifications.

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.