Expectation of primordial gravity waves generated during inflation

The inflationary paradigm is extremely successful regarding predictions of temperature anisotropies in the CMB. However, inflation also makes predictions for a CMB B-mode polarization, which has not been detected. Moreover, the standard inflationary paradigm is unable to accommodate the evolution from the initial state, which is assumed to be symmetric, into a nonsymmetric aftermath. In [G. León, A. Majhi, E. Okon, and D. Sudarsky, Phys. Rev. D 96, 101301(R), (2017)], we show that the incorporation of an element capable of explaining such a transition drastically changes the prediction for the shape and size of the B-mode spectrum. In particular, employing a realistic objective collapse model in a well-defined semiclassical context, we find that, while predictions of temperature anisotropies are nor altered (with respect to standard predictions), the B-mode spectrum gets strongly suppressed—in accordance with observations. Here, we present an in-depth discussion of that analysis, together with the details of the calculation.

Figure 1

The predicted B-mode polarization spectrum in three cases: the standard approach, the CSL inflationary collapse model and the Newtonian collapse scheme. In all cases, we set $\epsilon \simeq {10}^{-2}$. In the standard approach that value for the slow-roll parameter is consistent with a tensor to scalar ratio $r=0.12$.