Variations in the fine structure constant constraining gravity theories

TL;DR

This paper explores how the fine structure constant varies near gravitational sources and uses astrophysical data to constrain theories predicting such variations, combining quantum and semi-classical gravity considerations.

Contribution

It provides a novel analysis of local fine structure constant variations in gravitational fields and derives observational constraints on related theories.

Findings

Constraints on free parameters from white dwarf spectra

Expressions for spatial variation of alpha in weak gravity

Comparison with existing literature constraints

Abstract

In this paper, we investigate how the fine structure constant, $\alpha$, locally varies in the presence of a static and spherically symmetric gravitational source. The procedure consists in calculating the solution and the energy eigenvalues of a massive scalar field around that source, considering the weak-field regimen. From this result, we obtain expressions for an spatially variable fine structure constant by considering suitable modifications in the involved parameters admitting some scenarios of semi-classical and quantum gravities. Constraints on free parameters of the approached theories are calculated from astrophysical observations of the emission spectra of a white dwarf. Such constraints are finally compared with those ones obtained in the literature.