|Speaker:||Xian Gao (Titech)|
|Title:||Heavy modes and the oscillatory features in the curvature power spectrum|
|Date (JST):||Fri, Oct 18, 2013, 13:30 - 14:30|
|Place:||Seminar Room A|
We investigate cosmological perturbations in multiple field inflationary models where some of the degrees of freedom are heavy with respect to the Hubble parameter. We examine the consequences of a sudden turn along the inflationary trajectory, in particular the possible breakdown of the low energy effective theory in case the heavy modes are excited.
Resorting to a new "mass" basis in field space, instead of the usual adiabatic/entropic basis, we compute the power spectrum after the turn and compare with the result obtained from the low energy effective theory. In particular, we find two types of oscillatory features in the power spectrum: One is sinusoidal in $k$ due to the bending trajectory, the other is sinusoidal in $ln k$ due to the resonance of the perturbation with the oscillation of the background trajectory.