arXiv 2209.062832022-09-13hep-ph

抑制$D^{+}_{s}\rightarrow π^{+}\ell^{-}\ell^{+}$衰变中的长距离效应

Taming the long distance effects in the $D^{+}_{s}\rightarrow π^{+}\ell^{-}\ell^{+}$ decay

Marxil Sánchez, Genaro Toledo, I. Heredia De La Cruz

备注：: 17 pages, 10 figures, accepted in PRD

摘要：

半轻子衰变$D^{+}_{s}\rightarrow π^{+}\ell^{-}\ell^{+}$，其中$\ell=e, \ μ$，在寻找$D_{s}\rightarrow P\ell^{\pm}\ell^{\prime+}$形式的标准模型的抑制或禁止过程时用作参考通道。这个过程主要由从$η$到$ϕ$介子区域的强子共振所控制，通常由于相关的大的不确定性而被排除在外。在这项工作中，我们探讨的共振区域中所涉及的参数的作用。我们主要研究$ρ$和$ϕ$介子之间的相对强相（$δ_{ρϕ}$）。我们认为这个参数可以从$D^{+}_{s}\rightarrow π^{+}μ^{-}μ^{+}$衰变中的双μ子不变质量的LHCb数据中得到，并且我们进行了拟合，提供了第一种方法，我们得到了$δ_{ρϕ}=(0.44 \pm 0.24) π$。与此相反，考虑对这个相位不敏感的可观测量是有用的。我们首先计算在一个轻子发射相对于π介子的给定角度下轻子对的不变质量，然后计算在这个角度下的前后分布。我们发现，对于后者观察到的共振区域被涂抹，表现出不依赖于$δ_{ρϕ}$阶段，虽然全球性的影响观察到的比较与纯相空间的方法。为了考虑在更一般的情况下观察到这一点，我们分析了共振背景过程$D^{+}_{s}\rightarrow πππ$的行为，在标准模型中的短距离的贡献，和带电的希格斯介导的过程中给出的两个希格斯偶极子模型，表现出可区分的功能。

英文摘要：

The semileptonic decay $D^{+}_{s}\rightarrow π^{+}\ell^{-}\ell^{+}$, where $\ell=e, \ μ$, is used as a reference channel when looking for suppressed or forbidden processes of the standard model of the form $D_{s}\rightarrow P\ell^{\pm}\ell^{\prime+}$. The process is dominated by hadronic resonances from the $η$ to the $ϕ$ meson region, usually excluded due to the large uncertainties associated. In this work, we explore the role of the parameters involved in the resonance region. We focus in the relative strong phase between the $ρ$ and the $ϕ$ meson ($δ_{ρϕ}$). We argue that this parameter can be bound from LHCb data of the di-muon invariant mass in the $D^{+}_{s}\rightarrow π^{+}μ^{-}μ^{+}$ decay and we perform a fit to provide a first approach to it. We obtain $δ_{ρϕ}=(0.44 \pm 0.24) π$. In contradistinction, it would be useful to consider observables insensitive to this phase. We first compute the invariant mass of the lepton pair at a given angle of one of the leptons emission with respect to the pion, and then we compute the forward-backward distribution at such angle. We show that for the latter observable the resonance region is smeared, exhibiting no dependence on the $δ_{ρϕ}$ phase, although global effects are observed by comparing with the pure phase space approach. In order to consider this observable in more general scenarios, we analyse the behavior for the resonant background process $D^{+}_{s}\rightarrow πππ$, the short distance contribution in the standard model, and the charged Higgs mediated process as given by the two Higgs doublet model, which exhibit distinguishable features among themselves.

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英文摘要：

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