Minimal Supersymmetric Hybrid Inflation, Flipped SU(5) and Proton Decay

TL;DR

This paper explores minimal supersymmetric hybrid inflation models with a U(1) R-symmetry, analyzing their spectral index predictions and implications for proton decay in flipped SU(5), aligning with observational data.

Contribution

It presents a detailed calculation of the spectral index including radiative, supergravity, and soft SUSY breaking effects within a minimal supersymmetric hybrid inflation framework.

Findings

Spectral index n_s in the range 0.96-0.97 consistent with WMAP

U(1) R-symmetry suppresses dimension five proton decay

Proton lifetime estimated between 10^{34} and 10^{36} years

Abstract

Minimal supersymmetric hybrid inflation utilizes a canonical Kahler potential and a renormalizable superpotential which is uniquely determined by imposing a U(1) R-symmetry. In computing the scalar spectral index $n_s$ we take into account modifications of the tree level potential caused by radiative and supergravity corrections, as well as contributions from the soft supersymmetry breaking terms with a negative soft mass-squared term allowed for the inflaton. All of these contributions play a role in realizing $n_s$ values in the range 0.96-0.97 preferred by WMAP. The U(1) R-symmetry plays an important role in flipped SU(5) by eliminating the troublesome dimension five proton decay. The proton decays into $e^+ \pi^0$ via dimension six operators arising from the exchange of superheavy gauge bosons with a lifetime of order $10^{34}$-$10^{36}$ years.