论文标题
$ b \ to c $的研究$ \ bar {b}^* \ to v \ ell \barν_\ ell $衰减
Study of $b\to c$ induced $\bar{B}^* \to V \ell \barν_\ell$ decays
论文作者
论文摘要
在本文中，我们研究了以树为主的$ \ bar {b}^*_ {在轻夸克模型中获得的相关形式因素。 These decays involve much more helicity states relative to the corresponding $\bar{B}^* \to P \ell^- \barν_\ell$ and $\bar{B} \to V \ell^- \barν_\ell$ decays, and moreover, the contribution of longitudinal polarization mode ($V$ meson) is relatively small, $\sim 30\%$, compared with the相应的$ b $梅森腐烂。我们还计算了分支分数，Lepton自旋不对称，前向不对称和比率$ r_v^{\ ast（l）} \ equiv \ equiv \ frac {\ Mathcal {\ Mathcal {b}（\ bar {b} \barν_τ）} {\ Mathcal {b}（\ bar {b}^*\ to V \ ell^{\ prime-} \barν_{\ ell^{\ prime}}}} $（$ \ ell'= e \ e \ ,,μ$）。从数字上讲，$ \ bar {b}^* \ to v \ ell^{\ prime-} \barν_{\ ell^{\ prime}} $衰减的分支分数是$ {\ cal o}的级别（10^{ - 7}）$，并希望通过lhc casverle lhc，并希望通过lhc casvere。比率$ r_ {d^*\ ,, d^*_ s \ ,, j/ψ}^{\ ast（l）} $具有相对较小的理论上的不确定性，并且彼此接近，$ r^{*（l）} _ {d^*} _ {d^*} \ simeq r^simeq r^{ r^{*（l）} _ {j/ψ} \ simeq [0.26,0.27]〜（[0.27,0.29]）$，与以前的某些工作中的预测有所不同。预计未来的测量将对这些预测进行测试。
In this paper, we investigate the tree-dominated $\bar{B}^*_{u,d,s,c} \to V \ell^- \barν_\ell$ ($V=D^*_{u,d}\,,D^*_s\,,J/ψ$ and $\ell=e\,,μ\,,τ$) decays in the Standard Model with the relevant form factors obtained in the light-front quark model. These decays involve much more helicity states relative to the corresponding $\bar{B}^* \to P \ell^- \barν_\ell$ and $\bar{B} \to V \ell^- \barν_\ell$ decays, and moreover, the contribution of longitudinal polarization mode ($V$ meson) is relatively small, $\sim 30\%$, compared with the corresponding $B$ meson decays. We have also computed the branching fraction, lepton spin asymmetry, forward-backward asymmetry and ratio $R_V^{\ast(L)}\equiv \frac{\mathcal{B}(\bar{B}^*\to Vτ^- \barν_τ)}{\mathcal{B}(\bar{B}^*\to V \ell^{\prime-} \barν_{\ell^{\prime}})}$ ($\ell'=e\,,μ$). Numerically, the branching fractions of $\bar{B}^* \to V \ell^{\prime-} \barν_{\ell^{\prime}}$ decays are at the level of ${\cal O}(10^{-7})$, and are hopeful to be observed by LHC and Belle-II experiments. The ratios $R_{D^*\,,D^*_s\,,J/ψ}^{\ast(L)}$ have relatively small theoretical uncertainties and are close to each other, $R^{*(L)}_{D^*}\simeq R^{*(L)}_{D^*_s}\simeq R^{*(L)}_{J/ψ} \simeq [0.26,0.27]~([0.27,0.29])$, which are a bit different from the predictions in some previous works. The future measurements are expected to make tests on these predictions.
