# Gravitational scattering and radiation in the eikonal approach - Emerging Hawking-like radiation in gravitational scattering beyond the Planck scale

#### Gravitational scattering and radiation in the eikonal approach - Emerging Hawking-like radiation in gravitational scattering beyond the Planck scale

- Event time: 2:00pm
- Event date: 15th January 2020
- Speaker: Dr Dimitri Colferai (University of Florence)
- Location: Higgs Centre Seminar Room, Room 4305, James Clerk Maxwell Building (JCMB) James Clerk Maxwell Building Peter Guthrie Tait Road Edinburgh EH9 3FD GB

### Event details

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

Amati-Ciafaloni-Veneziano reduced-action model.

By resumming eikonal scattering diagrams, we

are able to derive the corresponding (unitary) coherent-state operator.

The resulting graviton spectrum turns out to be tuned on the gravitational

radius $R$ for small angles $\Theta_s << 1$ but, for sizeable

angles $\Theta_s \sim 1$ 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

$<N> \sim Gs >> 1$ 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 $E$.

### About Particle Physics Theory seminars

The Particle Physics Theory seminar is a weekly series of talks reflecting the diverse interests of the group. Topics include analytic and numerical calculations based on the Standard Model of elementary particle physics, theories exploring new physics, as well as more formal developments in gauge theories and gravity..