Weak decays of the \(\varvec{B_s}\) meson in the self-consistent covariant light-front approach

Abstract

We present a comprehensive study of weak transition form factors and decay observables of the \(B_s\) meson in transitions to pseudoscalar (P) and vector (V) mesons. The \(B_s \rightarrow P(V)\) form factors are calculated using the self-consistent covariant light-front quark model, with a model-independent z-series expansion calibrated to lattice QCD and phenomenological inputs for quark masses and \(\beta \) parameters. This enables reliable \(q^2\)-resolved predictions across the full kinematic range. Based on these form factors, we predict branching ratios and angular observables, including forward–backward asymmetries, polarization fractions, and leptonic convexity parameters for semileptonic decays. Nonleptonic two-body decay rates for \(B_s \rightarrow PP\) and \(B_s \rightarrow PV\) modes are also computed within the standard factorization framework using the same dynamical input. Comparisons with results from lattice QCD, light-cone sum rules, and other approaches are presented, highlighting both theoretical consistency and persistent tensions with experiment.