Constraint on a cosmological variation in the proton-to-electron mass ratio from electronic CO absorption

M. Daprà, M. L. Niu, E. J. Salumbides +2

Carbon monoxide (CO) absorption in the sub-damped Lyman-$\alpha$ absorber at redshift $z_{abs}\simeq 2.69$, toward the background quasar SDSS J123714.60+064759.5 (J1237+0647), was inve…