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arXiv 1303.5877hep-phhep-ex
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具有一般Yukawa结构的双Higgs二重态模型的味唯象

Flavor-phenomenology of two-Higgs-doublet models with generic Yukawa structure

Andreas Crivellin, Ahmet Kokulu, Christoph Greub

摘要:

我们进行了广泛的研究味道观测在2 HDM与通用汤川结构(MSSM的解耦极限)。我们研究的影响,风味物理和约束模型都从树级过程和循环可观的。模型的自由参数是重Higgs质量tan(β)和“非全纯”Yukawa耦合ε^f_ij(f=u,d,\ell)。在我们的分析中,我们以各种方式约束元素ε^f_ij:在第一步中,我们根据特胡夫特自然准则给出ε^f_ij的数量级约束。然后,我们从树级FCNC过程(B_s,d->μ^+μ^-,τ^--> μ^-μ^+μ^-,等等)约束了III型2 HDM的Yukawa结构。并且观察到除了ε ^u_32,31和ε ^u_23,13之外的所有味非对角元素必须非常小以满足实验界限。在第三步中,我们考虑Higgs介导的环对FCNC过程的贡献(b->s,dγ,μ->eγ等)。发现ε^u_13和ε^u_23也必须很小,而ε^u_31和ε^u_32的界特别弱。考虑到FCNC过程的限制,我们研究了树级带电Higgs交换的可能贡献大小。有趣的是,无约束元素ε^ u_{32,31}直接进入B->τν,B->Dτν和B->D*τν的分支比,我们表明,在这些过程中的SM预测的偏差可以同时解释。给出了轻子变味中性B介子衰变的分支比的上限,并将辐射轻子衰变与相应的中性流轻子衰变(τ^- ->μ^-μ^+μ^-,τ^- ->e^-μ^+μ^-和μ^- ->e^-e^+e^-)关联起来.一个详细的附录包含了一般标量-费米子-费米子耦合过程的所有相关信息。

英文摘要:

We perform an extensive study of flavor observables in a 2HDM with generic Yukawa structure (the decoupling limit of the MSSM). We examine the effects in flavor physics and constrain the model both from tree-level processes and loop-observables. The free parameters of the model are the heavy Higgs mass, tan(β) and the "non-holomorphic" Yukawa couplings ε^f_ij (f=u,d,\ell). In our analysis we constrain the elements ε^f_ij in various ways: In a first step we give order of magnitude constraints on ε^f_ij from 't Hooft's naturalness criterion. Then we constrain the Yukawa structure of the type-III 2HDM from tree-level FCNC processes (B_s,d->μ^+μ^-, τ^-->μ^-μ^+μ^-, etc.) and observe that all flavor off-diagonal elements except ε^u_32,31 and ε^u_23,13 must be very small in order to satisfy the experimental bounds. In a third step, we consider Higgs mediated loop contributions to FCNC processes (b->s,dγ, μ->eγ, etc.) finding that also ε^u_13 and ε^u_23 must be very small, while the bounds on ε^u_31 and ε^u_32 are especially weak. Taking into account the constraints from FCNC processes we study the possible size of contributions from tree-level charged Higgs exchange. Interestingly, the unconstrained elements ε^u_{32,31} enter directly the branching ratios for B->τν, B->Dτνand B->D*τνand we show that the deviations from the SM predictions in these processes can be explained simultaneously. We give upper limits on the branching ratios of the lepton flavor-violating neutral B meson decays and correlate the radiative lepton decays to the corresponding neutral current lepton decays (τ^- ->μ^-μ^+μ^-, τ^- ->e^-μ^+μ^- and μ^- ->e^-e^+e^-). A detailed appendix contains all relevant information for the considered processes for general scalar-fermion-fermion couplings.

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