We examine the impact of a nonminimal coupling of the inflaton to the Ricci scalar, 12ξRξ2, on the inflationary predictions. Such a nonminimal coupling is expected to be present in the inflaton Lagrangian on fairly general grounds. As a case study, we focus on the simplest inflationary model governed by the potential V∝φ2, using the latest combined 2015 analysis of Planck and the BICEP2/Keck Array. We find that the presence of a coupling ξ is favored at a significance of 99% C.L., assuming that nature has chosen the potential V∝φ2 to generate the primordial perturbations and a number of e-foldings N=60. Within the context of the same scenario, we find that the value of ξ is different from zero at the 2σ level. When considering the cross-correlation polarization spectra from the BICEP2/Keck Array and Planck, a value of r=0.038-0.030+0.039 is predicted in this particular nonminimally coupled scenario. Future cosmological observations may therefore test these values of r and verify or falsify the nonminimally coupled model explored here.
|Número de artículo
|Physical Review D - Particles, Fields, Gravitation and Cosmology
|Publicada - 19 may. 2015
|Publicado de forma externa