Blanke Monika, Buras Andrzej J, Recksiegel Stefan
CERN Theory Division, 1211 Geneva 23, Switzerland ; Institut für Theoretische Teilchenphysik, Karlsruhe Institute of Technology, Engesserstraße 7, 76128 Karlsruhe, Germany ; Institut für Kernphysik, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.
TUM Institute for Advanced Study, Lichtenbergstr. 2a, 85747 Garching, Germany ; Physik Department, Technische Universität München, James-Franck-Straße, 85747 Garching, Germany.
Eur Phys J C Part Fields. 2016;76(4):182. doi: 10.1140/epjc/s10052-016-4019-7. Epub 2016 Apr 2.
The Littlest Higgs model with T-parity (LHT) belongs to the simplest new physics scenarios with new sources of flavour and CP violation. The latter originate in the interactions of ordinary quarks and leptons with heavy mirror quarks and leptons that are mediated by new heavy gauge bosons. Also a heavy fermionic top partner is present in this model which communicates with the SM fermions by means of standard [Formula: see text] and [Formula: see text] gauge bosons. We present a new analysis of quark flavour observables in the LHT model in view of the oncoming flavour precision era. We use all available information on the CKM parameters, lattice QCD input and experimental data on quark flavour observables and corresponding theoretical calculations, taking into account new lower bounds on the symmetry breaking scale and the mirror quark masses from the LHC. We investigate by how much the branching ratios for a number of rare and decays are still allowed to depart from their SM values. This includes [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text]. Taking into account the constraints from [Formula: see text] processes, significant departures from the SM predictions for [Formula: see text] and [Formula: see text] are possible, while the effects in decays are much smaller. In particular, the LHT model favours [Formula: see text], which is not supported by the data, and the present anomalies in [Formula: see text] decays cannot be explained in this model. With the recent lattice and large input the imposition of the [Formula: see text] constraint implies a significant suppression of the branching ratio for [Formula: see text] with respect to its SM value while allowing only for small modifications of [Formula: see text]. Finally, we investigate how the LHT physics could be distinguished from other models by means of indirect measurements and discuss the consequences for quark flavour observables of not finding any LHT state in the coming years.
具有T宇称的最小希格斯模型（LHT）属于具有味和CP破坏新来源的最简单新物理情景。后者源于普通夸克和轻子与重镜像夸克和轻子的相互作用，这些相互作用由新的重规范玻色子介导。该模型中还存在一个重费米子顶伙伴，它通过标准的[公式：见正文]和[公式：见正文]规范玻色子与标准模型费米子相互作用。鉴于即将到来的味精确时代，我们对LHT模型中的夸克味可观测量进行了新的分析。我们使用了关于CKM参数、格点量子色动力学输入以及夸克味可观测量的实验数据和相应理论计算的所有可用信息，同时考虑了来自大型强子对撞机的对称破缺尺度和镜像夸克质量的新下限。我们研究了一些罕见的[公式：见正文]和[公式：见正文]衰变的分支比仍被允许偏离其标准模型值的程度。这包括[公式：见正文]、[公式：见正文]、[公式：见正文]、[公式：见正文]、[公式：见正文]、[公式：见正文]、[公式：见正文]和[公式：见正文]。考虑到[公式：见正文]过程的限制，[公式：见正文]和[公式：见正文]与标准模型预测可能存在显著偏差，而在[公式：见正文]衰变中的影响要小得多。特别是，LHT模型倾向于[公式：见正文]，但这并不被数据所支持，并且目前[公式：见正文]衰变中的异常现象无法在该模型中得到解释。利用最近的格点和大型强子对撞机的输入，施加[公式：见正文]限制意味着相对于其标准模型值，[公式：见正文]的分支比将受到显著抑制，而只允许对[公式：见正文]进行小的修改。最后，我们研究了如何通过间接测量将LHT物理与其他模型区分开来，并讨论了未来几年未发现任何LHT态对夸克味可观测量的影响。
