1.1. Hawking radiation as “tunnelling process”. In a couple of remarkable papers Parik...

Abstract. Tunnelling processes through black hole horizons have recently been investigated in the frame-work of WKB theory discovering interesting interplay with the Hawking radiation. A more precise and general account of that phenomenon has been subsequently given within the framework of QFT in curved spacetime by two of the authors of the present paper. In particular, it has been shown that, in the limit of sharp localization on opposite sides of a Killing horizon, the quantum correlation functions of a scalar field appear to have thermal nature, and the tunnelling probability is proportional to exp{−βHawkingE}. This local result is valid in every spacetime including a local Killing horizon, no field equation is nec-essary, while a suitable choice for the quantum state is relevant. Indeed, the two-point function has to verify a short-distance condition weaker than the Hadamard one. In this paper we consider a massive scalar quantum field with a φ3 self-interaction and we investigate the issue whether or not the black hole radiation can be handled at perturbative level, including the renormalisation contributions. We prove that, for the simplest model of the Killing horizon generated by the boost in Minkowski space-time, and referring to Minkowski vacuum, the tunnelling probability in the limit of sharp localization on opposite sides of the horizon preserves the thermal form proportional to exp{−βHE} even taking the one-loop renormalisation corrections into account. A similar result is expected to hold for the Unruh state i