Robust Constraint on a Drifting Proton-to-Electron Mass Ratio at z=0.89 from Methanol Observation at Three Radio Telescopes

Julija Bagdonaite, Mario Daprà, Paul Jansen +5

A limit on a possible cosmological variation of the proton-to-electron mass ratio $\mu$ is derived from methanol (CH${}_3$OH) absorption lines in the benchmark PKS1830$-$211 lensing ga…