ACP Seminar (Astronomy - Cosmology - Particle Physics)

Speaker: Lorenzo Sorbo (U of Massachusetts, Amherst)
Title: Naturally inflating on steep potentials through electromagnetic dissipation
Date (JST): Wed, Feb 05, 2014, 13:30 - 14:30
Place: Seminar Room A
Related File: 1130.pdf
Abstract: In many models of inflation the inflaton is an axion-like particle. Unfortunately, axion potentials in UV-complete theories appear to be too steep to drive inflation. I discuss how, even for a steep potential, natural inflation can occur if the coupling between axion and gauge fields is taken into account. Due to this coupling, quanta of the gauge field are produced by the rolling of the axion. If the coupling is large enough, such a dissipative effect slows down the axion, leading to inflation even for a steep potential. The spectrum of perturbations is quasi-scale invariant, but in the simplest construction its amplitude is larger than 10^(-9). I discuss a possible way out of this problem as well as the additional signatures of this model: potentially observable nongaussianities and a spectrum of chiral tensor modes.