Inflaton Condensate Fragmentation: Analytical Conditions and Application to α-Attractor Models

We study the stability of an inflaton condensate in the presence of attractive inflaton self-interactions, in order to determine analytical conditions on the self-interaction couplings under which the condensate undergoes fragmentation. As an application of our results, we consider the stability of the inflaton condensate in α-attractor inflation. We show that the stability of the condensate depends upon the value of α. For the T-model with n = 1, we find that it is unstable for α . 10−4. In this case it is expected that inflation will be followed by an oscillondominated era.