Paolo Benincasa (MPI, Munich)

Infra-red effects in expanding universes

Quantum field theory in expanding universes allows us to describe correlations at the end of inflation/beginning of the hot Big Bang, which sets the seeds for the subsequent evolution of the universe. However, such correlations turn out to suffer from infra-red divergencies whenever sufficiently light states are involved. Despite of recent works points toward a resolution of this issue for the leading divergencies in de Sitter space-time as the resummation of the infra-red modes, whose resummed probability distribution being compatible with the stochastic inflation proposal, a fundamental understanding is still missing. In this talk I will describe a novel approach to this issue discussing the possibility of defining infra-red safe observables.