GUT Inflation and Proton Decay after WMAP5

TL;DR

This paper explores inflation within non-supersymmetric GUTs like SU(5) and SO(10), linking inflationary parameters to GUT scales and proton decay predictions consistent with WMAP5 data.

Contribution

It demonstrates how Coleman-Weinberg and Higgs potentials can realize inflation in non-supersymmetric GUTs with specific spectral index and proton decay predictions.

Findings

Inflation scale around 10^{16} GeV consistent with WMAP5

Proton lifetime estimates between 10^{34} and 10^{38} years

In SO(10) models with axion dark matter, proton decay via leptoquark exchange occurs within observable ranges

Abstract

We employ Coleman-Weinberg and Higgs potentials to implement inflation in non-supersymmetric grand unified theories (GUTs) such as SU(5) and SO(10). To realize a scalar spectral index close to 0.96, as indicated by the most recent WMAP 5-year anlaysis, the energy scale of observable inflation turns out to be of order $10^{16}$ GeV. This implies a GUT symmetry breaking scale of similar magnitude, and proton lifetime of order $10^{34}$-$10^{38}$ years. In some SO(10) models with axion dark matter, the scalar leptoquark boson exchange leads to proton decay with a lifetime of order $10^{34}$-$10^{35}$ years.