Silvio Pallua

Horizon conformal entropy in Gauss–Bonnet gravity

We treat spherically symmetric black holes in Gauss–Bonnet gravity by imposing boundary conditions on fluctuating metric on the horizon. Obtained effective two-dimensional theory admits Virasoro algebra near the horizon. This enables, with the help of Cardy formula, evaluation of the number of states. Obtained results coincide with the known macroscopic expression for the entropy of black holes in Gauss–Bonnet gravity.

Gravitational Chern-Simons Lagrangians and black hole entropy

We analyze the problem of defining the black hole entropy when Chern-Simons terms are present in the action. Extending previous works, we define a general procedure, valid in any dimensions both for purely gravitational CS terms and for mixed gauge-gravitational ones. The final formula is very similar to Wald’s original formula valid for covariant actions, with a significant modification. Notwithstanding an apparent violation of covariance we argue that the entropy formula is indeed covariant.

Hawking fluxes, W∞ algebra and anomalies

We complete the analysis started in [arXiv:0804.0198] of the Hawking radiation calculated by means of anomaly techniques. We concentrate on a static radially symmetric BH, reduced to two dimensions. We compare the two methods used to derive the integrated Hawking radiation, based on the trace and diffeomorphism anomaly, respectively, and show that they can be reduced to the same basic elements. We then concentrate on higher moments of the Hawking radiation and on higher spin currents, and show that, similarly to trace anomalies, also diffeomorphism anomalies are absent from the conservation laws of higher spin currents. We show that the predictivity of the method is due to the W∞ current algebra underlying the effective model that describes matter around the black hole.We complete the analysis started in [arXiv:0804.0198] of the Hawking radiation calculated by means of anomaly techniques. We concentrate on a static radially symmetric BH, reduced to two dimensions. We compare the two methods used to derive the integrated Hawking radiation, based on the trace and diffeomorphism anomaly, respectively, and show that they can be reduced to the same basic elements. We then concentrate on higher moments of the Hawking radiation and on higher spin currents, and show that, similarly to trace anomalies, also diffeomorphism anomalies are absent from the conservation laws of higher spin currents. We show that the predictivity of the method is due to the

Entropy of Killing horizons from Virasoro algebra in D-dimensional extended Gauss–Bonnet gravity

W_\infty

On a quantum group invariant spin chain with non-local boundary conditions

current algebra underlying the effective model that describes matter around the black hole.

Gravitational Chern?Simons Lagrangian terms and spherically symmetric spacetimes

We treat D-dimensional black holes with Killing horizon for extended Gauss–Bonnet gravity. We use the Carlip method and impose boundary conditions on the horizon what enables us to identify Virasoro algebra and evaluate its central charge and Hamiltonian eigenvalue. The Cardy formula allows then to calculate the number of states and thus provides for a microscopic interpretation of entropy.

Higher curvature Lagrangians, conformal symmetry and microscopic entropy of Killing horizons

We treat a one parameter family of quantum spin models, which are quantum-group invariant as well as periodic in a certain sense, using Bethe states. We analyse its ground-state properties and obtain the surprising result that its spin becomes non-zero depending on the value of the parameter. Finite-size corrections allow us to obtain the central charge which is also spin dependent. Relations to other models are mentioned.

Violation of the string hypothesis and the Heisenberg XXZ spin chain

We show that for general spherically symmetric configurations, contributions of broad class of gravitational and mixed gauge-gravitational Chern–Simons (CS) terms to the equations of motion vanish identically in D > 3 dimensions. This implies that such terms in the action do not affect Birkhoffs theorem or any previously known spherically symmetric solutions. Furthermore, we investigate the thermodynamical properties using the procedure described in an accompanying paper. We find that in the D > 3 static spherically symmetric case, CS terms do not contribute to the entropy either. Moreover, if one requires only for the metric tensor to be spherically symmetric, letting other fields be unrestricted, the results extend almost completely, with only one possible exception—CS Lagrangian terms in which the gravitational part is just the n = 2 irreducible gravitational CS term.

Stationary rotating black holes in theories with gravitational Chern-Simons Lagrangian term

We impose a certain class of boundary conditions on Killing horizon and show for Lagrangians with arbitrary curvature dependence that one can identify a Virasoro algebra with nontrivial central charge and calculable Hamiltonian eigenvalue. Entropy can then be calculated from Cardy formula.

Conformal entropy for generalized gravity theories as a consequence of horizon properties

In this paper we count the numbers of real and complex solutions to Bethe constraints in the two-particle sector of the XXZ model. We find the exact n