"Fast--roll eras, primordial fluctuations and the lowest CMB multipoles: theory and observations."
Relatore: Claudio Destri- Dipartimento di Fisica, UniversitÓ di Milano-Bicocca
02 Settembre 2010 ore 16.00
|In single-field inflation the slow-roll attractor stage is generically
preceeded by a fast-roll stage which in turn follows a period of
decelerating expansion. The corresponding evolution of the scale
factor, the inflaton and the scalar quantum fluctuations are studied
in detail both semi-analytically and numerically, focusing in
particular on the effect of finite-time Bunch-Davies initial
conditions on the observable CMB spectrum. When these conditions are
imposed at the transition from fast-roll to slow-roll the lowest CMB
multipoles are depressed. Comparison with current observation data
show a marginal likelihood improvement over the assumption that the
low quadrupole is simply a manifestation of cosmic variance.