Ab initio nonadiabatic calculation of the sensitivity coefficients for the X 1Σ g + → B 1Σ u + ; C 1Πu lines of H2 to the proton-to-electron mass ratio

Abstract

Ab initio nonadiabatic calculations of the wavelengths λij of the individual lines of the Lyman X 1Σ g + → B 1Σ u + and Werner X 1Σ g + → C 1Πu series of molecular hydrogen and corresponding sensitivity coefficients K ij = dlnλij/dlnγ have been performed. These quantities are necessary for testing a possible change in the proton-to-electron mass ratio γ = m p/m e in the process of cosmological evolution. The basic contribution to K ij comes from the difference between the average kinetic energies of vibrations of combined states. Nonadiabatic interactions are important for a small number of locally-perturbed rovibrational levels of the B 1Σ u + and C 1Π u + states, for which change in K ij that is caused by nonadiabatic effects reaches 14%, which can lead to a significant systematic shift in the estimate of the parameter γ.