Variation of fundamental constants: theory and observations

TL;DR

This review discusses recent observational and theoretical efforts to detect variations in fundamental constants over time, highlighting methods, results, and potential enhancement effects in atomic and nuclear systems.

Contribution

It compiles and compares recent observational constraints on fundamental constant variations and proposes new scenarios for enhanced detection effects.

Findings

Quasar spectra constrain ot;/ to (1 b1 3) db7 10^{-16} yr^{-1}

Atomic clock data set the best limit on ot;/ of lpha to (-0.8 b1 0.8) db7 10^{-16} yr^{-1}

Variation effects can be significantly enhanced near narrow atomic, molecular, and nuclear energy levels.

Abstract

Review of recent works devoted to the variation of the fundamental constants is presented including atomic clocks, quasar absorption spectra, and Oklo natural nuclear reactor data. Assuming linear variation with time we can compare different results. From the quasar absorption spectra: $\dot{\mu}/\mu=(1 \pm 3) \times 10^{-16}$ yr$^{-1}$. A combination of this result and the atomic clock results gives the best limt on variation of $\alpha$: $\dot{\alpha}/\alpha=(-0.8 \pm 0.8) \times 10^{-16}$ yr$^{-1}$. The Oklo natural reactor gives the best limit on the variation of $m_s/\Lambda_{QCD}$ where $m_s$ is the strange quark mass. Huge enhancement of the relative variation effects happens in transitions between close atomic, molecular and nuclear energy levels. We suggest several new cases where the levels are very narrow. Large enhancement of the variation effects is also possible in cold atomic and molecular collisions near Feshbach resonance. Massive bodies (stars or galaxies) can also affect physical constants. They have large scalar charge $S$ proportional to number of particles which produces a Coulomb-like scalar field $U=S/r$. This leads to a variation of the fundamental constants proportional to the gravitational potential, e.g. $\delta \alpha/ \alpha = k_\alpha \delta (GM/ r c^2)$. We compare different manifestations of this effect.The strongest limit $k_\alpha +0.17 k_e= (-3.5\pm 6) \times 10^{-7}$.