Torsion-rotational transitions in methanol as a probe of fundamental physical constants -- electron and proton masses

TL;DR

This study uses torsion-rotational transitions in methanol molecules to set stringent limits on possible variations of the electron-to-proton mass ratio over cosmic timescales, supporting the constancy of fundamental constants.

Contribution

It introduces a novel astrophysical method employing methanol spectral lines to constrain variations in the electron-to-proton mass ratio with high precision.

Findings

Upper limit on relative change in mu: < 1.1×10^{-8}

Results align with previous constraints on fundamental constant variability

Demonstrates methanol as an effective probe for fundamental physics

Abstract

We report on the using of torsion-rotational transitions in the CH3OH and (13)CH3OH molecules to evaluate possible variations of the physical constant mu=m_e/m_p - the electron-to-proton mass ratio - from spectral observations of emission lines detected in the microwave range towards the dense molecular cloud Orion-KL. An estimate of the upper limit on the relative changes in mu is obtained by two independent ways - with (13)CH3OH lines and with the combination of (13)CH3OH and CH3OH lines. The calculated upper limit Delta mu/mu < 1.1*10^{-8} (1 sigma) is in line with the most stringent constraints on the variability of fundamental physical constants established by other astrophysical methods.