Grand Unification and Time Variation of the Gauge Couplings

TL;DR

This paper explores how astrophysical evidence of changing fundamental constants can be explained by grand unification theories, focusing on variations in the unification scale and their implications for cosmology.

Contribution

It analyzes models where the electromagnetic coupling variation arises from changes in the unification scale, linking astrophysical observations to grand unification frameworks.

Findings

Time variation of the electromagnetic coupling could be due to unification scale changes.

Recent hints suggest a possible time change in the proton-electron mass ratio.

Implications for baryogenesis are discussed.

Abstract

Astrophysical indications that the fine structure constant is time dependent are discussed in the framework of grand unification models. A variation of the electromagnetic coupling constant could either be generated by a corresponding time variation of the unified coupling constant or by a time variation of the unification scale, or by both. The case in which the time variation of the electromagnetic coupling constant is caused by a time variation of the unification scale is of special interest. It is supported in addition by recent hints towards a time change of the proton-electron mass ratio. Possible implications for baryogenesis are discussed.