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

TL;DR

This paper calculates form factors and decay rates for rare semileptonic B and B_c meson decays using a relativistic quark model, achieving good agreement with experimental data and providing new decay predictions.

Contribution

It introduces a comprehensive relativistic quark model calculation of form factors for rare B and B_c meson decays, including relativistic effects and wave function transformations.

Findings

Calculated decay branching fractions and polarization fractions match experimental data.

Predicted decay rates for B_c mesons are provided.

Relativistic effects significantly influence form factor calculations.

Abstract

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. Good agreement of the obtained results with the recent detailed experimental data on the B\to K^{(*)}\mu^+\mu^- decays from Belle and CDF is found. Predictions for the rare semileptonic decays of the B_c mesons are given.