MG15 - Talk detail

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Abstract

We generalize the semiclassical treatment of graviton radiation to gravitational scattering at very large energies E >> m_P and finite scattering angles Theta_s, so as to approach the collapse regime. Our basic tool is the extension of the recently proposed, unified form of radiation to the ACV reduced-action model. By resumming eikonal scattering diagrams, we are able to derive the corresponding (unitary) coherent-state operator. The resulting graviton spectrum, tuned on the gravitational radius R, fully agrees with previous calculations for small angles Theta_s << 1 but, for sizeable angles Theta_s ~ 1 acquires an exponential cutoff of the large frequency region (omega > 1/R), due to energy conservation, so as to emit a finite fraction of the total energy. In the approach-to-collapse regime we find a radiation enhancement due to large tidal forces, so that the whole energy is radiated off, with a large multiplicity <N> ~ Gs >> 1 and a well-defined frequency cutoff of order 1/R. The latter corresponds to the Hawking temperature for a black hole of mass somewhat smaller than E.

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