Selected decays of $B_{s}$ meson in covariant confined quark model

TL;DR

This study analyzes a broad set of $B_s$ decays within the covariant confined quark model (CCQM) to test SM hadronic dynamics and CKM-driven amplitudes. It employs an effective Hamiltonian framework with Wilson coefficients and a CCQM-based description of hadronic form factors and decay constants to compute widths for hadronic and semileptonic channels. The results show good agreement for semileptonic decays $B_s^0 \to D_s^- \mu^+ \nu_\mu$ and $B_s^0 \to K^- \mu^+ \nu_\mu$, while tensions arise in several hadronic modes (notably $B_s^0 \to D_s^- \pi^+$, $D_s^- \rho^+$, $\phi J/\psi$, and especially $\phi \overline{D^{0}}$ and $\phi \eta_c$), indicating possible factorization breakdown and the importance of long-distance effects. The work highlights the value of cross-model comparisons to isolate genuine hadronic physics and suggests further theoretical developments to incorporate nonfactorizable and long-distance contributions in nonleptonic $B_s$ decays.

Abstract

We present a study of various $B_{s}$ meson decays, including hadronic and semileptonic final states with different spins and diagram topologies. The covariant confined quark model is employed to describe hadronic effects, and our analysis serves as a broad test of the current understanding of the underlying dynamics within the Standard Model. The level of agreement with experimental data varies across channels: it is good for the semileptonic decays $B_{s}^{0}\to D_{s}^{-}μ^{+}ν_μ$ and $B_{s}^{0}\to K^{-}μ^{+}ν_μ$; acceptable for the hadronic modes $B_{s}^{0}\to D_{s}^{-}D^{+}$ and $B_{s}^{0}\to K^{-}π^{+}$; marginal for $B_{s}^{0}\to D_{s}^{-}π^{+}$, $B_{s}^{0}\to D_{s}^{-}ρ^{+}$, and $B_{s}^{0}\toφ\,J/ψ$; and significantly discrepant for $B_{s}^{0}\toφ\,\overline{D^{0}}$ and $B_{s}^{0}\toφ\,η_{c}$. We argue that the observed inconsistencies may arise from the breakdown of naive factorization and unaccounted long-distance effects. In particular, the channels $B_{s}^{0}\to D_{s}^{-}π^{+}$ and $B_{s}^{0}\to D_{s}^{-}ρ^{+}$ are theoretically among the cleanest nonleptonic decays, yet they exhibit persistent discrepancies also reported by other theoretical groups.

Figures (9)

• Figure 1: The feynman diagram of decays $B_{s}^{0}\to D_{s}^{-}+\pi^{+}$ and $B_{s}^{0}\to D_{s}^{-}+\rho^{+}$.
• Figure 2: The Feynman diagrams of the decay $B_{s}^{0}\to D_{s}^{-}+D^{+}$.
• Figure 3: The Feynman diagram of the decay $B_{s}^{0}\to\phi+\overline{D^{0}}$.
• Figure 4: The Feynman diagrams of decays $B_{s}^{0}\to\phi+\eta_{c}$ and $B_{s}^{0}\to\phi+J/\psi$.
• Figure 5: The Feynman diagrams of decays $B_{s}^{0}\to D_{s}^{-}+\mu^{+}\nu$ and $B_{s}^{0}\to K^{-}+\mu^{+}\nu$.