论文标题
重新访问$ b \ tocτν$过渡：在SM中和之外
Revisit to the $b\to cτν$ transition: in and beyond the SM
论文作者
论文摘要
我们对$ b \ tocτν$数据进行分析，包括$ r（d^{（*）}）$，$ r（j/ψ）$，$p_τ（d^{*}）$和$ f_l^{d^*} $，内部和超越标准模型（SM）。我们将$ b \适合d^{（*）} $ HQET参数化中的HADRONIC形式对晶格和轻率总和规则（LCSR）结果，应用了对应于$ j^p = 1^p = 1^-$，$ 1^+，$ 1^+$，$ 0^+$，$ 0^ - $ 0^ - $ 0^ - $ 0^+$的一般强度单位界限。使用螺旋性幅度之间获得的HQET关系，我们在单个螺旋度振幅上给出了强大的单位性界限，该振幅可用于BGL拟合中。使用拟合的形式，并考虑到$ r（d^{（*）}）$的最新美女测量值，我们研究了$ b \ tocτν$异常的模型无关的和leptoquark模型的解释。具体而言，我们考虑使用单个操作员，两个操作员新物理（NP）和NP型号，具有单个$ r_2 $，$ s_1 $或$ u_1 $ leptoquark，它应该能够解决$ b \ b \ b \ b \ tocτν$ anomalies，我们的结果显示$ r_2 $ lepto $ leptoark lepto s nesitive是$ leptoark smode的限制。 b（b_c \ toτν）<10 \％$。此外，我们基于当前的形式研究和NP的分析，对SM和NP场景/Leptoquark模型进行了预测。
We perform an analysis of the $b\to cτν$ data, including $R(D^{(*)})$, $R(J/ψ)$, $P_τ(D^{*})$ and $F_L^{D^*}$, within and beyond the Standard Model (SM). We fit the $B\to D^{(*)}$ hadronic form factors in the HQET parametrization to the lattice and the light-cone sum rule (LCSR) results, applying the general strong unitarity bounds corresponding to $J^P=1^-$, $1^+$, $0^-$ and $0^+$. Using the obtained HQET relations between helicity amplitudes, we give the strong unitarity bounds on individual helicity amplitudes, which can be used in the BGL fits. Using the fitted form factors and taking into account the most recent Belle measurement of $R(D^{(*)})$ we investigate the model-independent and the leptoquark model explanations of the $b\to cτν$ anomalies. Specifically, we consider the one-operator, the two-operator new physics (NP) scenarios and the NP models with a single $R_2$, $S_1$ or $U_1$ leptoquark which is supposed to be able to address the $b\to cτν$ anomalies, and our results show that the $R_2$ leptoquark model is in tension with the limit $\mathcal B(B_c\to τν)<10\%$. Furthermore, we give predictions for the various observables in the SM and the NP scenarios/leptoquark models based on the present form factor study and the analysis of NP.
