arXiv 1701.040292017-01hep-phhep-ex

排列双Higgs模型中的$Λ_b\to Λ(\to pπ^-)μ^+μ^-$衰变

The $Λ_b\to Λ(\to pπ^-)μ^+μ^-$ decay in the aligned two-Higgs-doublet model

Quan-Yi Hu, Xin-Qiang Li, Ya-Dong Yang

备注：: 26 pages, 2 figures, and 4 tables; More discussions added, final version published in the journal

摘要：

稀有重子衰变$Λ_b\to Λ(\to pπ^-)μ^+μ^-$提供了有价值的补充信息相比，相应的介子$b\to sμ^+μ^-$过渡。在本文中，使用最新的高精度格点QCD计算的$Λ_b\toΛ$跃迁形状因子，我们研究了这个有趣的衰变在对齐的两个Higgs的二重态模型，特别注意的手征翻转运营商的带电标量产生的影响。为了在这个衰变中提取完整的角度系数，我们考虑以下十个角度观测值，它们可以从随后的宇称违反$Λ\to pπ^-$衰变的分析中导出：微分分支分数${\rm d}{\cal B}/{\rm d}q^2$，纵向极化分数$F_L$，轻子、强子和轻子-强子组合侧前后不对称性$A_{\rm FB}^\ell$、$A_{\rm FB}^Λ$和$A_{\rm FB}^{\ellΛ}$，以及其它五个不对称观测量$Y_i$ ~（$i={\rm 2,\,3s,\,3sc,\,4s,\,4sc}$）。详细的数值比较SM和NP值之间的这些角度观测。研究发现，在包含$B\to X_sγ$分支分数和$b\to s\ell\ell$数据最新的整体拟合结果的约束下，右手半轻子算符$O^{\prime}_{9,10}$的贡献除了能调和$B^0\to K^{\ast 0}μ^+μ^-$衰变中观测到的$P_5^{\prime}$异常外，还能增强仓$[15,20]~{\rm GeV}^2$中的${\rm d}{\cal B}/{\rm d}q^2$和$A_{\rm FB}^\ell$的值，得到与当前LHCb测量一致的结果.

英文摘要：

The rare baryonic decay $Λ_b\to Λ(\to pπ^-)μ^+μ^-$ provides valuable complementary information compared to the corresponding mesonic $b\to sμ^+μ^-$ transition. In this paper, using the latest high-precision lattice QCD calculation of the $Λ_b\toΛ$ transition form factors, we study this interesting decay within the aligned two-Higgs-doublet model, paying particularly attention to effects of the chirality-flipped operators generated by the charged scalars. In order to extract the full set of angular coefficients in this decay, we consider the following ten angular observables that can be derived from the analysis of the subsequent parity-violating $Λ\to pπ^-$ decay: the differential branching fraction ${\rm d}{\cal B}/{\rm d}q^2$, the longitudinal polarization fraction $F_L$, the lepton-, hadron- and combined lepton-hadron-side forward-backward asymmetries $A_{\rm FB}^\ell$, $A_{\rm FB}^Λ$ and $A_{\rm FB}^{\ellΛ}$, as well as the other five asymmetry observables $Y_i$~($i={\rm 2,\,3s,\,3sc,\,4s,\,4sc}$). Detailed numerical comparisons are made between the SM and NP values for these angular observables. It is found that, under the constraints from the inclusive $B\to X_sγ$ branching fraction and the latest global fit results of $b\to s\ell\ell$ data, the contributions of right-handed semileptonic operators $O^{\prime}_{9,10}$, besides reconciling the $P_5^{\prime}$ anomaly observed in $B^0\to K^{\ast 0}μ^+μ^-$ decay, could also enhance the values of ${\rm d}{\cal B}/{\rm d}q^2$ and $A_{\rm FB}^\ell$ in the bin $[15,20]~{\rm GeV}^2$, leading to results consistent with the current LHCb measurements.

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英文摘要：

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