P oS(BHs, GR and Strings)035 Corrections to the Bekenstein-Hawking entropy in

The brick wall model is a semi-classical approach to understand the microscopic origin of black hole entropy. In this approach, the entropy of the black hole arises due to the canonical entropy of matter fields outside the black hole event horizon, evaluated at the Hawking temperature. Usually, in the brick wall model, the density of states and the resulting canonical entropy of the matter fields are calculated at the leading order (in terms of h̄) in the WKB approximation. We extend this approach and compute the brick wall entropy of a quantum scalar field around static and spherically symmetric black holes at the higher orders in the WKB approximation. We find that the brick wall model generally predicts corrections to the Bekenstein-Hawking entropy in all spacetime dimensions. We compare our results with the sub-leading contributions to the black hole entropy that has been obtained from various other approaches