论文标题
近期LHCB和BABAR测量的Singlet Vector Leptoquark模型
Singlet vector leptoquark model facing recent LHCb and BABAR measurements
论文作者
论文摘要
最近，LHCB实验发布了比率$ r（λ_c）= {\ rm br}（λ_b\ \λ_cCτ\barν_τ）/{\ rm br}（λ_b\toλ_cμ\barν_μ）$的第一个测量。此外，Babar实验报告了Upsilon Meson $υ（3s）$的松性衰减比的新结果，即$ r_ {υ（3S）} = {\ rm br}（υ（3S）\ to t to to to to to to to to to to to to to to t toτ^+τ^+τ^ - ）/{\ rm Br}（3s）（3S）（3S）（3S）这两个测量值都低于其相应的标准模型预测（赤字），分别偏离$ \ sim1.1σ$和$ \ sim1.8σ$。此外，LHCB最近介绍了对Lepton风味的首次搜索，违反衰减$ B^0 \ to K^{\ ast 0}μ^\pmτ^\ mp $。在这些新数据的激励下，在这项工作中，我们研究了它们对单线矢量leptoquark（$ u_1 $）的现象学的影响，该模型通过进行全球拟合分析，以涉及$ b $ ersons（$ b $ b $ meson anomalies）的半衰减衰减的提示。通常，我们发现$ u_1 $型号的最小版本为1.8 TEV可以成功解释$ b $中元异常，同时与所有其他风味可观察的物品和LHC界限兼容。有趣的是，我们的研究表明，新的观察力$ r（λ_c）$和$ r_ {υ（3s）} $产生了强烈的张力，从而对全球拟合产生了非平凡的影响。 LHCB和Belle II实验的未来改进将有助于了解其互补性。此外，我们还分析了预期灵敏度对Belle II的风味可观测值的影响，以进一步测试$ u_1 $型号。最后，我们研究了$ u_1 $模型还可以提供对穆恩异常磁矩的合并解释的最小假设。
Very recently the LHCb experiment released the first measurement of the ratio $R(Λ_c) = {\rm BR}(Λ_b \to Λ_cτ\barν_τ)/{\rm BR}(Λ_b \to Λ_cμ\barν_μ)$. Moreover, the BABAR experiment reported a new result of the leptonic decay ratio of Upsilon meson $Υ(3S)$, namely, $R_{Υ(3S)} = {\rm BR}(Υ(3S) \to τ^+τ^-)/{\rm BR}(Υ(3S) \to μ^+μ^-)$. Both measurements are below their corresponding Standard Model predictions (deficit), deviating by $\sim 1.1σ$ and $\sim 1.8σ$, respectively. Moreover, the LHCb recently presented the first search of the lepton flavor violating decay $B^0 \to K^{\ast 0}μ^\pmτ^\mp$. Motivated by these new data, in this work we study their impact on the phenomenology of the singlet vector leptoquark ($U_1$) model addressing the hints of lepton flavor universality violation in the semileptonic decays of $B$ mesons ($B$ meson anomalies), by carrying out a global fit analysis. In general, we found that a minimal version of the $U_1$ model with a mass of 1.8 TeV can successfully explain the $B$ meson anomalies, while being compatible with all other flavor observables and LHC bounds. Interestingly, our study shows that the new observables $R(Λ_c)$ and $R_{Υ(3S)}$ generate strong tension, leading to non-trivial effects on the global fit. Future improvements at the LHCb and Belle II experiments would help to understand their complementarity. Moreover, we also analyze the impact of the expected sensitivity on flavor observables at Belle II to provide a further test of the $U_1$ model. Finally, we study the minimal assumptions under which the $U_1$ model could, in addition, provide a combined explanation of the anomalous magnetic moment of the muon.
