Rare semileptonic decays of B and B_c mesons in the relativistic quark model

Understand

Rare semileptonic decays of B and B_c mesons are investigated in the framework of the QCD-motivated relativistic quark model based on the quasipotential approach.

• Form factors parametrizing the matrix elements of the weak transitions between corresponding meson states are calculated with the complete account of the relativistic effects including contributions of intermediate negative energy states and relativistic transformations of the meson wave functions.
• The momentum transfer dependence of the form factors is reliably determined in the whole accessible kinematical range.
• On this basis the total and differential branching fractions of the B\to K^{(*)}l^+l^-(\nu\bar\nu) and B_c\to D_s^{(*)}l^+l^-(\nu\bar\nu), B_c\to D^{(*)}l^+l^-(\nu\bar\nu) decays as well as the longitudinal polarization fractions F_L of the final vector meson and the muon forward-backward asymmetries A_{FB} are calculated.