Transitions of Bc → ψ(1S,2S) and the modified harmonic oscillator wave function in the light front quark model

The LHCb Collaboration has systematically measured the rates of B-c -> J/psi K, B-c J/psi D-s, B-c -> J/psi D-s*, and B-c -> psi(2S)pi. The new data enable us to study relevant theoretical models and further determine the model parameters. In this work, we calculate the form factors for the transitions B-c -> J/psi and B-c -> psi(2S) numerically and then determine the partial widths of the semileptonic and nonleptonic decays. The theoretical predictions on the ratios of Gamma(B-c -> J/psi K)/Gamma(B-c -> J/psi pi), Gamma(B-c -> J/psi D-s)/Gamma(B-c -> J/psi pi), and Gamma(B-c -> J/psi D-s*)/Gamma(B-c -> J/psi pi) are consistent with data within only 1 sigma. Especially, for calculating Gamma(B-c -> psi(2S)X) the modified harmonic oscillator wave function which we developed in early works is employed, and the results indicate that the modified harmonic oscillator wave function works well.