Thermal partition function of photons and gravitons in a Rindler wedge.

The thermal partition function of photons in any covariant gauge and gravitons in the harmonic gauge, propagating in a Rindler wedge, are computed using a local ζ-function regularization approach. The correct Planckian leading order temperature dependence T 4 is obtained in both cases. For the photons, the existence of a surface term giving a negative contribution to the entropy is confirmed, as earlier obtained by Kabat, but this term is shown to be gauge dependent in the four-dimensional case and, therefore is discarded. It is argued that similar terms could appear dealing with any integer spin s ≥ 1 in the massless case and in more general manifolds. Our conjecture is checked in the case of a graviton in the harmonic gauge, where different sur∗Electronic address: [email protected] †Electronic address: [email protected]