2026/07/20 by You-Ya Yang, Zhi-Qing Zhang, Zhi-Jie Sun
#hep-ph #hep-ex
The semileptonic and nonleptonic decays of the Υ(nS) with n=1,2,3,4 are investigated within the covariant light-front quark model (CLFQM). Using the form factors of the transitions Υ(nS) → B(c) obtained from the CLFQM, we calculate the branching ratios of the decays Υ(nS)→ B(c)ℓν_ℓ and Υ(nS)→ B(c)M with ℓ=e,μ,τ and M referring to π(ρ),K(*),D(*),D(*)s. One can find that the branching ratios of the decays Υ(3S)→ Bcℓν_ℓ are the largest among those of considered semileptonic decays and can amount to 10-9; As to the nonleptonic decays, Υ(3S)→ Bcρ and Υ(3S)→ BcD(*)s have the largest branching ratios, which reach up to 10-10. Given the identification and detection efficiency of final states, searching for these weak decay modes should be fairly challenging in future experiments. The forward-backward asymmetry AFB and the longitudinal polarization fraction fL are also calculated for those semileptonic decays.