IA/U.Lisboa Seminar - Quantum quenches during inflation - 22 dezembro 2016

Queen Mary, University of London

 

We propose a new technique to study fast transitions during inflation, by studying the dynamics of quantum quenches in an O(N) scalar field theory in de Sitter spacetime. We compute the time evolution of the system using a non-perturbative large-N limit approach. We derive the self-consistent mass equation for several physically relevant transitions of the parameters of the theory, in a slow motion approximation. Our computations reveal that the effective mass after the quench evolves in the direction of recovering its value before the quench, but stopping at a different asymptotic value, in which the mass is strictly positive. Furthermore, we tentatively find situations in which the effective mass can be temporarily negative, thus breaking the O(N) symmetry of the system for a certain time, only to then come back to a positive value, restoring the symmetry. We argue the relevance of our new method in a cosmological scenario.