Communications in Theoretical Physics ›› 2020, Vol. 72 ›› Issue (8): 085401. doi: 10.1088/1572-9494/ab7ecb

• Gravitation Theory, Astrophysics and Cosmology • Previous Articles     Next Articles

Quadratic, Higgs and hilltop potentials in Palatini gravity

Nilay Bostan()   

  1. Department of Physics and Astronomy, University of Iowa, 52242, Iowa City, IA, United States of America
  • Received: 2019-11-26 Revised: 2020-02-15 Accepted: 2020-03-10 Published: 2020-08-01

Abstract:

In this work, we study the theory of inflation with the non-minimally coupled quadratic, standard model Higgs, and hilltop potentials, through ξφ2R term in Palatini gravity. We first analyze observational parameters of the Palatini quadratic potential as functions of ξ for the high-N scenario. In addition to this, taking into account that the inflaton field φ has a non-zero vacuum expectation value v after inflation, we display observational parameters of well-known symmetry-breaking potentials. The types of potentials considered are the Higgs potential and its generalizations, namely hilltop potentials in the Palatini formalism for the high-N scenario and the low-N scenario. We calculate inflationary parameters for the Palatini Higgs potential as functions of v for different ξ values, where inflaton values are both φ > v and φ < v during inflation, as well as calculating observational parameters of the Palatini Higgs potential in the induced gravity limit for high-N scenario. We illustrate differences between the Higgs potential's effect on ξ versus hilltop potentials, which agree with the observations for the inflaton values for φ < v and ξ, in which v ≪ 1 for both these high and low N scenarios. For each considered potential, we also display ns − r values fitted to the current data given by the Keck Array/BICEP2 and Planck collaborations.

Key words: non-minimal inflation, Palatini gravity, Keck Array/BICEP2 and Planck results