In this work we study the Higgs boson decays into two photons and into one photon and one $Z$ gauge boson within the context of the non-linear Effective Field Theory called the Electroweak Chiral Lagrangian. We present a detailed computation of the corresponding amplitudes to one-loop level in the covariant $R_ξ$ gauges. We assume that the fermionic loop contributions are as in the Standard Model and focus here just in the computation of the bosonic loop contributions. Our renormalization program and the anatomy of the various contributions participating in the $R_ξ$ gauges are fully explored. With this present computation we demonstrate the gauge invariance of the EChL result, not only for the case of on-shell Higgs boson, but also for the most general and interesting case of off-shell Higgs boson. We finally analyse and conclude on the special relevance of the Goldstone boson loops, in good agreement with the expected chiral loops behaviour in Chiral Lagrangians. We perform a systematic comparison with the corresponding computation of the Standard Model in the $R_ξ$ gauges and with the previous EChL results in the unitary gauge. This work represents the first computation within the EChL of these Higgs observables to one-loop in the most general $R_ξ$ gauges and with a full renormalization program description, not yet fully explored in the previous literature and which is different to the most frequently used in the linear Effective Field Theory (SMEFT).
Anatomy of the Higgs fits: a first guide to statistical treatments of the theoretical uncertainties
基于最近和即将到来的大型强子对撞机数据的希格斯玻色子耦合的研究打开了一个新的窗口，物理学超越了标准模型。在本文中，我们提出了一个统计指南的一致性治疗的理论不确定性进入希格斯速率拟合。贝叶斯和频率论的方法进行了系统的分析，在一个统一的形式主义。我们提出的边际似然分析表达式，同时实施的实验和理论的不确定性。我们回顾了理论误差的各种来源（QCD，EFT，PDF，生产模式污染.）。所有这些单独的不确定性都在基于矩的考虑的帮助下被彻底地结合起来。希格斯探测通道之间的理论相关性似乎会影响希格斯耦合空间中最佳拟合区域的位置和大小。我们讨论了个别理论误差的先验分布的形状的经常性问题，并发现一个近高斯先验产生的错误组合。我们还开发了偏见的方法，这是一种替代边缘化提供更保守的结果。介绍了应用偏倚原理的统计框架，并提出了偏倚的两种实现方式。最后，根据统计处理，标准模型预测的希格斯信号强度被发现位于$68\%$或$95\%$置信水平区域内，这些置信水平区域是从$7$和$8$ TeV LHC数据集的最新分析中获得的。
Karlsruhe Institute of Technology（卡尔斯鲁厄理工学院）；Institut für Theoretische Teilchenphysik, Karlsruhe Institute of Technology（卡尔斯鲁厄理工学院理论粒子物理研究所）；Institut für Astroteilchenphysik, Karlsruhe Institute of Technology（卡尔斯鲁厄理工学院天体粒子物理研究所）；Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所）；Kaiping Neutrino Research Center（开平中微子研究中心）；Laboratory for Particle Physics, PSI Center for Neutron and Muon Sciences（PSI中子与缪子科学中心粒子物理实验室）；Physik-Institut, Universitat Zurich（苏黎世大学物理学院）；School of Physics and Institute for Collider Particle Physics, University of the Witwatersrand（威特沃特斯兰德大学物理学院及对撞机粒子物理研究所）
