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"Fast--roll eras, primordial fluctuations and the lowest CMB multipoles: theory and observations."

Relatore: Claudio Destri- Dipartimento di Fisica, UniversitÓ di Milano-Bicocca

Aula Newton
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.