Variation of fundamental constants in space and time: theory and observations

TL;DR

This paper reviews recent theoretical and observational studies on the possible variation of fundamental constants over space and time, including new results and proposed measurements to detect such variations.

Contribution

It provides a comprehensive review of recent work on fundamental constant variations and introduces new experimental proposals and data analyses.

Findings

Constraints from Big Bang nucleosynthesis data

Results from Oklo natural reactor analysis

Proposals for enhanced measurement effects in spectra

Abstract

Review of recent works devoted to the temporal and spatial variation of the fundamental constants and dependence of the fundamental constants on the gravitational potential (violation of local position invariance) is presented. We discuss the variation of the fine structure constant $\alpha=e^2/\hbar c$, strong interaction and fundamental masses (Higgs vacuum), e.g. the electron-to-proton mass ratio $\mu=m_e/M_p$ or $X_e=m_e/\Lambda_{QCD}$ and $X_q=m_q/\Lambda_{QCD}$. We also present new results from Big Bang nucleosynthesis and Oklo natural nuclear reactor data and propose new measurements of enhanced effects in atoms, nuclei and molecules, both in quasar and laboratory spectra.