S-matrix and Quantum Tunneling in Gravitational Collapse

TL;DR

This paper links the S-matrix in gravitational collapse to quantum tunneling using the ACV reduced-action approach, revealing insights into inelastic processes, absorption effects, and quantum corrections that refine semiclassical predictions.

Contribution

It introduces a novel interpretation of the S-matrix as a tunneling amplitude in an effective field space within the ACV framework, including quantum corrections that improve semiclassical results.

Findings

S-matrix related to tunneling amplitude in gravitational collapse

Absorption effects below critical impact parameter

Quantum corrections tend to smooth semiclassical results

Abstract

Using the recently introduced ACV reduced-action approach to transplanckian scattering of light particles, we show that the $S$-matrix in the region of classical gravitational collapse is related to a tunneling amplitude in an effective field space. We understand in this way the role of both real and complex field solutions, the choice of the physical ones, the absorption of the elastic channel associated to inelastic multigraviton production and the occurrence of extra absorption below the critical impact parameter. We are also able to compute a class of quantum corrections to the original semiclassical $S$-matrix that we argue to be qualitatively sensible and which, generally speaking, tend to smooth out the semiclassical results.