OPTICAL APPROACH FOR THE THERMAL PARTITION-FUNCTION OF PHOTONS

The optical manifold method to compute the one-loop effective action i n a static space-time is extended from the massless scalar field to th e Maxwell field in any Feynman-like covariant gauge. The method is app lied to the case of the Rindler space obtaining the same results as th e point-splitting procedure. The result is free from Kabat's surface t erms which instead affect the zeta-function or heat-kernel approaches working directly in the static manifold containing conical singulariti es. The relation between the optical method and the direct zeta-functi on approach on the Euclidean Rindler manifold is discussed both in the scalar and the photon cases. Problems with the thermodynamic self-con sistency of the results obtained from the stress tensor in the case of the Rindler space are pointed out.