Speaker
Mr
Fernando Gil Domínguez
(UCM)
Description
In flat spacetime, an instability problem arises in the homogeneous field configuration of a system with concave potential. We extend that analysis to an accelerated expanding universe where the potential is not needed to be concave in order to have instabilities. We study the particular case of an inflationary universe with a slow-roll phase and calculate the lifetime associated to its decay. In order to avoid this instability problem, with an estimation of the size of the observable universe at this epoch we obtain an upper bound for the Hubble parameter which is incompatible with standard models of inflation based on a minimally coupled scalar inflaton.
