A Pati-Salam Version of Subcritical Hybrid Inflation

TL;DR

This paper introduces a Pati-Salam symmetric subcritical hybrid inflation model that aligns with current cosmological data, addresses monopole production, and integrates solutions for particle physics issues like the $$ problem and proton decay.

Contribution

It presents a novel inflation model combining Pati-Salam symmetry with specific symmetry protections, compatible with observational data and capable of addressing multiple particle physics challenges.

Findings

Achieves $r = 0.084$ and $n_s = 0.0963$, consistent with Planck and BICEP2/Keck data.

Dilutes monopoles via waterfall field breaking PS during inflation.

Incorporates a $$ problem solution and proton decay suppression within the inflation framework.

Abstract

In this paper we present a model of subcritical hybrid inflation with a Pati-Salam [PS] symmetry group. Both the inflaton and waterfall fields contribute to the necessary e-foldings of inflation, while only the waterfall field spontaneously breaks PS hence monopoles produced during inflation are diluted during the inflationary epoch. The model is able to produce a tensor-to-scalar ratio, $r < 0.09$ consistent with the latest BICEP2/Keck and Planck data, as well as scalar density perturbations and spectral index, $n_s$, consistent with Planck data. For particular values of the parameters, we find $r = 0.084$ and $n_s = 0.0963$. The energy density during inflation is directly related to the PS breaking scale, $v_{PS}$. The model also incorporates a $\mathbb{Z}_4^R$ symmetry which can resolve the $\mu$ problem and suppress dimension 5 operators for proton decay, leaving over an exact $R$-parity. Finally the model allows for a complete three family extension with a $D_4$ family symmetry which reproduces low energy precision electroweak and LHC data.