2007/12/20 by D. Amati, M. Ciafaloni, G. Veneziano · 1 citation
Physics and Astronomy · #hep-th
paper · pdf · doi:10.1088/1126-6708/2008/02/049
published as JHEP0802:049,2008 · 39 pages, 5 figures; added discussion sect. 7, added references, acknowledgements
arxiv created 2007/12/20 · arxiv updated 2009/12/01
Extending our previous results on trans-Planckian (Gs ≫ ℏ) scattering of light particles in quantum string-gravity we present a calculation of the corresponding S-matrix from the region of large impact parameters (b ≫ G√(s)>λs) down to the regime where classical gravitational collapse is expected to occur. By solving the semiclassical equations of a previously introduced effective-action approximation, we find that the perturbative expansion around the leading eikonal result diverges at a critical value b = bc = O(G√(s)), signalling the onset of a new (black-hole related?) regime. We then discuss the main features of our explicitly unitary S-matrix -- and of the associated effective metric -- down to (and in the vicinity of) b = bc, and present some ideas and results on its extension all the way to the b → 0 region. We find that for b<bc the physical field solutions are complex-valued and the S-matrix shows additional absorption, related to a new production mechanism. The field solutions themselves are, surprisingly, everywhere regular, suggesting a quantum-tunneling -- rather than a singular-geometry -- situation.