Does Current Data Prefer a Non-minimally Coupled Inflaton?

Abstract

We examine the impact of a non-minimal coupling of the inflaton to the Ricci scalar, $\frac{1}{2}\xi R{\varphi }^2$, on the inflationary predictions. Such a non-minimal 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 $V\propto {\varphi }^2$, using the latest combined 2015 analysis of Planck and BICEP2/Keck Array. We find that the presence of a coupling $\xi$ is favoured at a significance of $99\%$ CL, assuming that nature has chosen the potential $V\propto {\varphi }^2$ 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 $\xi$ is different from zero at the $2\sigma$ level. When considering the cross-correlation polarization spectra from BICEP2/Keck Array and Planck, a value of $r=0.038_{-0.030}^{+0.039}$ is predicted in this particular non-minimally coupled scenario. Future cosmological observations may therefore test these values of $r$ and verify or falsify the non-minimally coupled model explored here.

5 pages, 4 figures and 2 tables. Published version

References in corpus (9)

• The Standard Model Higgs boson as the inflaton
• A Joint Analysis of BICEP2/Keck Array and Planck Data
• On Inflation with Non-minimal Coupling
• The Lyth Bound of Inflation with a Tilt
• ${\varphi }^2$ or Not ${\varphi }^2$: Testing the Simplest Inflationary Potential
• Gravity Waves From Non-Minimal Quadratic Inflation
• Can CMB data constrain the inflationary field range?
• Phenomenological approaches of inflation and their equivalence
• Theoretical bounds on the tensor-to-scalar ratio in the cosmic microwave background

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• Non-Minimal Two-Loop Inflation
• On the viability of m**2 phi**2 and natural inflation
• Neutron Star Structure in the Presence of Nonminimally Coupled Scalar Fields