Features of heavy physics in the CMB power spectrum

by Dr Subodh Patil

Thursday 5 May 2011, 16:00 → 17:00 Europe/Brussels

E/3rd floor-E.349 - Seminar room (E.349) (Marc de Hemptinne (chemin du Cyclotron, 2, Louvain-la-Neuve))

It is widely appreciated that the observed properties of the CMB are accurately reproduced by a scale invariant spectrum of primordial metric fluctuations, strongly suggesting an earlier epoch of slow roll inflation. However, direct and accurate reconstructions of the primordial spectrum from the raw CMB data is limited by degeneracies in the priors and the systematics adopted in our analyses. It may very well be that the data can be better fit by a primordial spectrum which deviates from scale invariance in possessing certain features. In this talk we discuss how such features (in the form of damped, superimposed oscillations) can arise from the non-decoupling of certain heavy operators in multi-field inflation if the inflaton trajectory curves enough in field space. In the two-field case where one field is sufficiently massive, we are able to compute an effective theory for the adiabatic mode encapsulating the relevant operators of the full multi-field dynamics. This effective theory exhibits a modified speed of sound that is a functional of the curvature of the background inflaton trajectory, anticipating non-Gaussian signatures directly correlated to the features imprinted in the power spectrum.