论文标题
使用新的Monte Carlo Event Generator，对$ {\ bar b}^0 \ in $ {\ bar b}^0 \ in $ {\ bar b}^0 \ in $ {\ bar b}^0 \ in $ {\ bar b}^0 \ in y y y y homomaly的影响
Implications for the $ΔA_{FB}$ anomaly in ${\bar B}^0\to D^{*+}\ell^- {\barν}$ using a new Monte Carlo Event Generator
论文作者
论文摘要
Belle，Babar和LHCB的$ B $物理学的最新实验结果表明，弱$ b \ to C $充电 - 电流中的新物理（NP）以及$ b \ to $ b \ to s $中性流动过程。在这里，我们将重点放在充电的情况下，特别是衰减模式$ \ bar {b}^0 \ to d^{*+} \ ell^ - \barν$带有$ \ ell = e $和$μ$。当前的世界平均值$ r_d $和$ r_d^{*} $与标准模型（SM）预测$3.4σ$不同，而最近在前进的不对称测量中观察到了新的异常，$ a_ {fb} $ in $ a_ {fb} $，in $ \ bar bar {b}^0 \ bar {b}^0 \ decy d^$ d^ - 发现$ΔA_{fb} = a_ {fb}（b \ to d^{*}μν） - a_ {fb}（b \ to d^{*}eν）$在2019年Belle数据分析中与SM预测中的$4.1σ$相比。在这项工作中，我们探讨了$ΔA_{fb} $异常的可能解决方案，并指出其他Angular可观察物中相关的NP信号。在超越标准模型物理学的情况下，必须存在角度可观察物之间的这些相关性。我们强调了$δ$类型可观察到的重要性，这些可观测值是通过获取MUON和电子模式的可观察到的差异而获得的。这些数量取消了SM中的外形不确定性，并允许对NP进行干净的测试。这些有趣的结果还表明，迫切需要在$ \ bar {b}^0 \ to d^{*+} \ ell^ - \barν$衰减中进行改进的仿真和分析技术。在这里，我们还描述了一种基于EVTGEN的新蒙特卡洛事件生成工具，我们开发了该工具，以模拟$ \ bar {b}^0 \ to d^{*+} \ ell^ - ν$中的NP签名，这是由于SM和NP amplitudes之间的干扰而产生的。然后，我们讨论对Belle II数据的1、5、50和250 AB $^{ - 1} $的NP耦合敏感的可观察到的前景，这似乎非常适合这类测量。
Recent experimental results in $B$ physics from Belle, BaBar and LHCb suggest new physics (NP) in the weak $b\to c$ charged-current and the $b\to s$ neutral-current processes. Here we focus on the charged-current case and specifically on the decay modes $\bar{B}^0\to D^{*+}\ell^- \barν$ with $\ell = e$ and $μ$. The world averages of the ratios $R_D$ and $R_D^{*}$ currently differ from the Standard Model (SM) predictions by $3.4σ$ while recently a new anomaly has been observed in the forward-backward asymmetry measurement, $A_{FB}$, in $ \bar{B}^0\to D^{*+}μ^- \barν$ decay. It is found that $ΔA_{FB} = A_{FB}(B\to D^{*} μν) - A_{FB} (B\to D^{*} e ν)$ is around $4.1σ$ away from the SM prediction in an analysis of 2019 Belle data. In this work we explore possible solutions to the $ΔA_{FB}$ anomaly and point out correlated NP signals in other angular observables. These correlations between angular observables must be present in the case of beyond the Standard Model physics. We stress the importance of $Δ$ type observables that are obtained by taking the difference of the observable for the muon and the electron mode. These quantities cancel form factor uncertainties in the SM and allow for clean tests of NP. These intriguing results also suggest an urgent need for improved simulation and analysis techniques in $\bar{B}^0\to D^{*+}\ell^- \barν$ decays. Here we also describe a new Monte Carlo Event-generator tool based on EVTGEN that we developed to allow simulation of the NP signatures in $\bar{B}^0\to D^{*+}\ell^- ν$, which arise due to the interference between the SM and NP amplitudes. We then discuss prospects for improved observables sensitive to NP couplings with 1, 5, 50, and 250 ab$^{-1}$ of Belle II data, which seem to be ideally suited for this class of measurements.
