Hawking radiation and ultraviolet regulators.

Polchinski has argued that the prediction of Hawking radiation must be independent of the details of unknown high-energy physics because the calculation may be performed using ‘nice slices’, for which the adiabatic theorem may be used. If this is so, then any calculation using a manifestly covariant — and so slice-independent — ultraviolet regularization must reproduce the standard Hawking result. We investigate the dependence of the Hawking radiation on such a short-distance regulator by calculating it using a Pauli–Villars regularization scheme. We find that the regulator scale, Λ, only contributes to the Hawking flux by an amount that is exponentially small in the large variable Λ/TH ≫ 1, where TH is the Hawking temperature; in agreement with Polchinski’s arguments. We also solve a technical puzzle concerning the relation between the short-distance singularities of the propagator and the Hawking effect.