标题： Z-Z' 混合与 SU(3)_C x SU(3)_L x U(1)_X 模型中的 Z 介导的 FCNCs 显示英文标题

标题： Z-Z' Mixing and Z-Mediated FCNCs in SU(3)_C x SU(3)_L x U(1)_X Models

摘要： 大多数现有的关于FCNC过程在331模型中的分析，基于规范群SU(3)_C x SU(3)_L x U(1)_X，只考虑了新的重中性规范玻色子Z'的树级交换。 然而由于Z-Z'混合，也存在来自Z玻色子的相应贡献，通常被忽略。 我们计算了这些贡献对不同β值下的ΔF=2过程以及稀有K、B_s和B_d衰变的影响，其中β参数区分了不同的331模型，并且对于SU(3)_L群下的不同费米子表示。 我们找到了一个关于β、M_Z、M_Z'和tan(bar{贝塔})的一般表达式，这与2希格斯双重态模型中熟悉的表达式不同，与文献中提到的有所不同。 我们特别研究了β=±n/sqrt{3}的模型，其中n=1,2，这些模型最近我们在B_{s,d}→μ^+ μ^- 和 B_d→K^*(K)μ^+ μ^-的新数据背景下进行了研究。 我们发现，在ΔF=2跃迁和衰变的情况下，例如B_d→K^*μ^+μ^-，这些新贡献确实可以被忽略，因为它们被带电轻子的矢量Z耦合所抑制。 然而，树级Z交换对敏感于轴矢量耦合的衰变的贡献，如B_{s,d}->mu^+ mu^-和B_d->K mu^+ mu^-，以及末态包含中微子的衰变，如b->s nu bar{nu}转换，K^+->pi^+ nu bar{你}和K_L->pi^0 nu bar{nu}不能被普遍忽略，其大小取决于beta，tan(bar{贝塔})和M_Z'。 我们首次在这些模型中分析了epsilon'/epsilon的比值，包括Z'和Z的贡献。 我们在331模型中对电弱精确观测量的分析清楚地表明，电弱精确观测量中的NP效应与味观测量中的NP效应之间的相互作用，将来可能有助于识别最受欢迎的331模型。 显示英文摘要

摘要： Most of the existing analyses of FCNC processes in the 331 models, based on the gauge group SU(3)_C x SU(3)_L x U(1)_X, take only into account tree-level exchanges of a new heavy neutral gauge boson Z'. However due to the Z-Z' mixing also corresponding contributions from Z boson are present that are usually neglected. We calculate the impact of these contributions on Delta F=2 processes and rare K, B_s and B_d decays for different values of a parameter beta, which distinguishes between various 331 models and for different fermion representations under the SU(3)_L group. We find a general expression for the Z-Z' mixing in terms beta, M_Z, M_Z' and tan(bar{beta}), familiar from 2 Higgs Doublet models, that differs from the one quoted in the literature. We study in particular the models with beta=+-n/sqrt{3} with n=1,2 which have recently been investigated by us in the context of new data on B_{s,d}->mu^+ mu^- and B_d->K^*(K)mu^+ mu^-. We find that these new contributions can indeed be neglected in the case of Delta F=2 transitions and decays, like B_d->K^*mu^+mu^-, where they are suppressed by the small vectorial Z coupling to charged leptons. However the contributions of tree-level Z exchanges to decays sensitive to axial-vector couplings, like B_{s,d}->mu^+ mu^- and B_d->K mu^+ mu^-, and those with neutrinos in the final state, like b->s nu bar{nu} transitions, K^+->pi^+ nu bar{nu} and K_L->pi^0 nu bar{nu} cannot be generally neglected with size of Z contributions depending on beta, tan(bar{beta}) and M_Z'. We analyze for the first time the ratio epsilon'/epsilon in these models including both Z' and Z contributions. Our analysis of electroweak precision observables within 331 models demonstrates transparently that the interplay of NP effects in electroweak precision observables and those in flavour observables could allow in the future to identify the favourite 331 model.