Talks by Ugo Moschella

Particle decay in the de Sitter universe

Ugo Moschella University of Insubria
We study particle decay in the de Sitter spacetime as given by first order perturbation theory in an interacting quantum field theory. We discuss first a general construction of bosonic two-point functions, including a recently discovered class of tachyonic theories that do exist in the de Sitter spacetime at discrete negative values of the squared mass parameter and have no Minkowskian counterpart. We show then that for fields with masses above a critical mass $m_c$ there is no such thing as particle stability, so that decays forbidden in flat space-time do occur there.