Informal Pizza Seminar

Nongaussianity and Spectral Distortion from Tachyonic Preheating

Neil Barnaby

McGill

Models of hybrid inflation are popular in the literature and arise naturally in realistic theories of high energy physics like string theory and supersymmetry. Inflation ends in these models with a spinodal instability which leads to nonperturbative particle production called tachyonic preheating. Preheating can generate large scale curvature perturbations at the end of inflation and thus may lead to large nongaussianity in the CMB. I will show that non-observation of nongaussian signatures in the CMB puts interesting constraints on the parameter space of hybrid inflation. I will also consider the possibility of second order cosmological fluctuations becoming large and distorting the power spectrum.