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arXiv 1806.05090hep-ph
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探索$τ^- \to K^-π^0ν_τ $中$CP$破坏的新物理贡献

Exploring new physics contributions to $CP$ violation in $τ^- \to K^-π^0ν_τ $

David Delepine, Gaber Faisel, Carlos A. Ramirez

摘要:

对非极化$τ$在$τ\to Kπν$等过程中可能违反CP的一般分析。本文在具有一般Yukawa结构的双Higgs偶线模型和轻子模型的框架下,导出了支配$\vertΔS \vert=1$半轻子τ衰变的有效哈密顿量的新贡献.在这些模型中,我们列出了所有的运营商,在有效的哈密顿量,并提供其相应的威尔逊系数的解析表达式。此外,我们分析了不同的贡献,来自标量,矢量和张量强子电流,在产生直接CP不对称的$τ^-\to K^-π^0ν_τ$的衰变率的作用。我们表明,非零的直接CP不对称的衰变率的$τ^-\to K^-π^0ν_τ$可以产生由于存在的两个,弱相对应的张量算子和强相位差的威尔逊系数之间的干扰所产生的形状因子表示的矩阵元素的矢量和张量强子电流。考虑到所有相关的约束条件后,我们发现,所产生的直接CP不对称的顺序是$10^{-8}$这是几个数量级大于标准模型预测。我们还表明,在具有一般Yukawa结构的双Higgs二重态模型中,直接局域或非积分CP破坏可以达到$0.3$ %,与实验结果相差不远。这种不对称性可能是由于具有不同弱相位的矢量和标量贡献之间的干扰而产生的,而在SM中不是这种情况。

英文摘要:

A general analysis of possible violation of CP in processes like $τ\to Kπν$, for unpolarized $τ$ is presented. In this paper, we derive the new contributions to the effective Hamiltonian governs $\vertΔS \vert=1$ semileptonic tau decays in the framework of two Higgs doublet model with generic Yukawa structure and Leptoquarks models. Within these models, we list all operators, in the effective Hamiltonian and provide analytical expression for their corresponding Wilson coefficients. Moreover, we analyze the role of the different contributions, originating from the scalar, vecor and tensor hadronic currents, in generating direct CP asymmetry in the decay rate of $τ^-\to K^-π^0ν_τ$. We show that non vanishing direct CP asymmetry in the decay rate of $τ^-\to K^-π^0ν_τ$ can be generated due to the presence of both, the weak phase in the Wilson coefficient corresponding to the tensor operator and the strong phase difference resulting from the interference between the form factors expressing the matrix elements of the vector and tensor hadronic currents. After taking into account all relevant constraints, we find that the generated direct CP asymmetry is of order $10^{-8}$ which is several orders of magnitude larger than the standard model prediction. We show also that, in two Higgs doublet model with generic Yukawa structure , direct local or non integrated CP violation can be as large as $0.3$ % not far from experimental possibilities. This kind of asymmetry can be generated due to the interference between vector and scalar contributions with different weak phases which is not the case in the SM.

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