http://arxiv.org/abs/1409.1784
Here, we revisit the question of possible preheating of entropy modes in a two field model with a massless inflaton coupled to a matter scalar field. Using a perturbative approximation to the covariant method we demonstrate that there is indeed a parametric instability of the entropy mode which then at second order leads to exponential growth of the curvature fluctuation on super-Hubble scale. Back-reaction effects shut off the induced curvature fluctuations, but only after their amplitude has grown to a phenomenologically unacceptable value. This confirms previous results obtained using different methods.
H. Moghaddam, R. Brandenberger, Y. Cai, et. al.
Mon, 8 Sep 14
61/69
Comments: 12 pages