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 $$B_s$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>B</mml:mi> <mml:mi>s</mml:mi> </mml:msub> </mml:math> meson in transitions to pseudoscalar ( P ) and vector ( V ) mesons. The $$B_s \rightarrow P(V)$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mi>B</mml:mi> <mml:mi>s</mml:mi> </mml:msub> <mml:mo>→</mml:mo> <mml:mi>P</mml:mi> <mml:mrow> <mml:mo>(</mml:mo> <mml:mi>V</mml:mi> <mml:mo>)</mml:mo> </mml:mrow> </mml:mrow> </mml:math> 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 $$\beta $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>β</mml:mi> </mml:math> parameters. This enables reliable $$q^2$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mi>q</mml:mi> <mml:mn>2</mml:mn> </mml:msup> </mml:math> -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 $$B_s \rightarrow PP$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mi>B</mml:mi> <mml:mi>s</mml:mi> </mml:msub> <mml:mo>→</mml:mo> <mml:mi>P</mml:mi> <mml:mi>P</mml:mi> </mml:mrow> </mml:math> and $$B_s \rightarrow PV$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mi>B</mml:mi> <mml:mi>s</mml:mi> </mml:msub> <mml:mo>→</mml:mo> <mml:mi>P</mml:mi> <mml:mi>V</mml:mi> </mml:mrow> </mml:math> 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.