Weak decays of B_c meson in a QCD potential model

The leptonic and semileptonic decay properties of B_c meson are studied in a QCD potential model. The CKM element for the leptonic decay is calculated by evaluating its decay constant. With the help of the Isgur–Wise function, the form factors and the CKM element for semileptonic decay are also calculated. The variation in four-momentum square in the two decays demands two different scales of the strong coupling constant α_s. Thus, a two-scale picture is evident from the study. We compute the decay constant f_p for leptonic decay and form factors for semileptonic decay with two different Λ scales in a specific prescription where it is related to the strong coupling α_s. Within the potential model, we find the scale for leptonic decay is Λ ≤ 150 GeV and for semileptonic decay is Λ ≥ 0.410 GeV. (author)