Viable Chaotic Inflation as a Source of Neutrino Masses and Leptogenesis

TL;DR

This paper demonstrates that a supergravity-based chaotic inflation model naturally leads to neutrino masses and leptogenesis, with predictions consistent with Planck data, and discusses solutions to related cosmological problems.

Contribution

It introduces a supergravity chaotic inflation model that naturally incorporates the seesaw mechanism and leptogenesis, linking inflation to neutrino physics.

Findings

Reheating temperature around 10^{13} GeV allows thermal leptogenesis.

Inflaton decay produces leptons and Higgs fields, connecting inflation to neutrino mass generation.

Predicted scalar spectral index and tensor-to-scalar ratio match Planck observations.

Abstract

We show that the seesaw mechanism as well as leptogenesis are natural outcomes of a viable chaotic inflation in supergravity. The inflation model contains two superfields, the inflaton and stabilizer fields, which, being singlets under the standard model gauge symmetry, naturally couple to the lepton and Higgs doublets. The inflaton decays into leptons and Higgs fields, and the reheating temperature is predicted to be of O(10^{13}) GeV, for which thermal leptogenesis is possible. On the other hand, gravitinos are copiously produced, and various solutions to the gravitino problem are discussed. We also argue that, if the shift symmetry of the inflaton is explicitly broken down to a discrete one, neutrino Yukawa couplings are periodic in the inflaton field, and masses of leptons and Higgs do not blow up even if the inflaton takes super-Planckian field values. The inflaton potential is given by a sum of sinusoidal functions with different height and periodicity, the so-called multi-natural inflation. We show that the predicted scalar spectral index and tensor-to-scalar ratio lie in the region favored by the Planck data.