Gravitational Waves from Fermionic Preheating
Meriniemi, Tuukka (University of Helsinki)

I will present fresh numerical results for the gravitational wave spectrum produced during fermionic preheating. In our model, the inflaton is coupled to a fermionic field via Yukawa interaction. After inflation, the inflaton decays into fermionic species at preheating. During preheating the inflaton oscillates coherently around its minimum. The effective mass of the fermionic field is proportional to the inflatons amplitude and is therefore time-dependent. When the effective mass is near to its minimum the amplitude of the fermionic field changes rapidly and non-adiabatically. This gives rise to large inhomoginities which produces gravitational waves. Gravitational wave production from bosonic preheating has been studied by several groups previously, but this is the very first time that gravitational wave production from fermionic preheating has been explored.