AI 中文总结
研究\(\Upsilon(nS)\)的半轻子和非轻子衰变，基于协变光前夸克模型计算相关跃迁形状因子及衰变分支比等，发现\(\Upsilon(3S)\to B_c\ell\nu_\ell\)分支比最大，还计算了半轻子衰变的不对称性和极化分数。
AI 中文摘要
在协变光前夸克模型（CLFQM）中研究了\(n = 1,2,3,4\)时\(\Upsilon(nS)\)的半轻子和非轻子衰变。利用CLFQM得到的\(\Upsilon(nS) \to B_{(c)}\)跃迁形状因子，计算了\(\Upsilon(nS)\to B_{(c)}\ell\nu_\ell\)和\(\Upsilon(nS)\to B_{(c)}M\)（\(\ell = e,\mu,\tau\)，\(M\)指\(\pi(\rho),K^{(*)},D^{(*)},D^{(*)}_s\)）的衰变分支比。发现\(\Upsilon(3S)\to B_c\ell\nu_\ell\)的分支比在考虑的半轻子衰变中最大可达\(10^{-9}\)；非轻子衰变中\(\Upsilon(3S)\to B_c\rho\)和\(\Upsilon(3S)\to B_cD^{(*)}_s\)分支比最大达\(10^{-10}\)。还计算了半轻子衰变的前后不对称性\(A_{FB}\)和纵向极化分数\(f_L\)。
英文摘要
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 $Υ(nS) \to B_{(c)}$ obtained from the CLFQM, we calculate the branching ratios of the decays $Υ(nS)\to B_{(c)}\ellν_\ell$ and $Υ(nS)\to B_{(c)}M$ with $\ell=e,μ,τ$ and $M$ referring to $π(ρ),K^{(*)},D^{(*)},D^{(*)}_s$. One can find that the branching ratios of the decays $Υ(3S)\to B_c\ellν_\ell$ are the largest among those of considered semileptonic decays and can amount to $10^{-9}$; As to the nonleptonic decays, $Υ(3S)\to B_cρ$ and $Υ(3S)\to B_cD^{(*)}_s$ 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 $A_{FB}$ and the longitudinal polarization fraction $f_L$ are also calculated for those semileptonic decays.
Comments25 pages, 4 figures
