论文标题
调查$υ（ns）\至τ^+τ^ - $ $衰减在leptoquark方案中
Investigating $ Υ(ns) \to τ^+ τ^- $ decay in the Leptoquark scenario
论文作者
论文摘要
Several measurements on $R_D, R_{D^*}$, and $R_{J/ ψ}$ by the BaBar, Belle, and LHCb experiments show significant deviations from their Standard Model (SM) predictions, which illustrate the fact that the concept of lepton flavor universality (LFU) is violated in semileptonic $B$ meson as well as leptonic $υ（ns）（n = 1,2,3）$衰减。最近，巴巴尔实验宣布，$1.8σ$级别，$r_υ（3s）= {\ rm br}（υ（3S）\至τ\barτ）/{\ rm br}（υ（3S）\ toμ\barμ）$显示出对SM的接受。这些令人着迷的发现表明，新物理学在$ b \ tocτ\barν$过渡中可能含义，这又创造了一个新的方向，可以在$ b \ bar {b} \ toτ\barτ$过程中寻找新物理。因此，对$ b \cτ\barν$进程的新物理贡献不可避免地将$ b \ bar {b} \转换为τ\barτ$ transitions。在这里，我们通过使用$ r_d $，$ r_d $，$ r {_d*} $，$ r_ {j/ψ} $，$ r_ {x_c} $，$ r_d*} $，$χ^{2} $拟合来约束新参数。 In this context, we investigate the effect of constrained new physics couplings on the branching ratios and LFU parameters $R_{Υ(ns)}$ through leptoquark models such as $S_3, \tilde{S_1}, \tilde{R_2}, U_1, U_3 $ and $ V_2$.
Several measurements on $R_D, R_{D^*}$, and $R_{J/ ψ}$ by the BaBar, Belle, and LHCb experiments show significant deviations from their Standard Model (SM) predictions, which illustrate the fact that the concept of lepton flavor universality (LFU) is violated in semileptonic $B$ meson as well as leptonic $Υ(ns)(n=1,2,3)$ decays. Recently BaBar experiment announced that at $1.8σ$ level, $R_Υ(3s)= {\rm Br}(Υ(3s) \to τ\barτ)/{\rm Br}(Υ(3s) \to μ\barμ)$ shows an acceptance with the SM. These fascinating findings point towards the possible implication of new physics in the $b \to c τ\barν$ transitions, which in turn, creates a new direction to look for new physics in $b \bar{b} \to τ\barτ $ process. Thereby, the new physics contributions to the $b \to c τ\barν$ process would inevitably alter the $b \bar{b} \to τ\barτ $ transitions. Here we conduct a $χ^{2}$ fit to constraining the new parameters by using the measured values of $ R_D$, $R{_D*}$, $ R_{J/ ψ}$, $ R_{X_C}$, $F_L (D^*)$ and $P_τ (D^*)$. In this context, we investigate the effect of constrained new physics couplings on the branching ratios and LFU parameters $R_{Υ(ns)}$ through leptoquark models such as $S_3, \tilde{S_1}, \tilde{R_2}, U_1, U_3 $ and $ V_2$.
