Course on high energy scattering for particles and strings

Who: Paolo di Vecchia (Nordita)
When: Monday, February 3, 2014 at 11:00
Tuesday, February 4, 2014 at 11:00
Wednesday, February 5, 2014 at 11:00

Where: The CP³ meeting room

High-energy scattering in a gravitational theory is dominated by graviton exchanges. Since gravitons are coupled to energy, perturbative unitarity is violated. In these lectures  we will discuss how unitarity is recovered in the scattering  of both a  particle and   a closed string  on D-branes. We will also discuss the cases of particle-particle and string-string scattering.

In the case of  a particle one must re-sum the perturbative series getting the eikonal c-number phase that is unitary. From the eikonal phase one can then compute the deflection angle experienced by the particle scattering on a set of Dp-branes. The case of string is more interesting because one gets the eikonal operator  that is an operator in the Hilbert space of the string states.  In this case, unlike the scattering of a particle, elastic unitarity is violated and, in order to recover the full unitarity,  one must include inelastic processes.  This allows us to identify the microscopic closed-string states that must be included for satisfying the unitarity requirement for large impact parameter.

Slides from his talks are available here.