Discrete Glimpses of the Physics Landscape after the Higgs Discovery

What is the Higgs boson telling us? What else is there? How do we find it? This talk discusses these current topics in particle physics in the wake of the Higgs discovery, with particular emphasis on the discrete symmetries CP and R-parity, not forgetting flavour physics and dark matter, and finishing with some remarks about possible future colliders. KCL-PH-TH/2015-02, LCTS/2015-01, CERN-PH-TH/2015-008 1. The Story so far Run 1 of the LHC has brought the apotheosis of the Standard Model (SM). The SM has predicted successfully many cross sections for particle and jet production measured at the LHC [1], as seen in Fig. 1. These successes include QCD jet production cross sections, which agree with SM predictions over large ranges in energy and many orders of magnitude, measurements of single and multiple W± and Z0 production, as well as multiple measurements of top quark production, both pairwise and singly and in association with vector bosons. Moreover, Run 1 of the LHC has also brought the discovery by CMS and ATLAS of a (the?) Higgs boson [2], whose production has by now been observed in three different production channels, as also seen in Fig. 1, again with cross sections in agreement with the SM predictions. A major theme of this talk is what we already know about this newly-discovered particle. Meanwhile, over there in flavour space, the Cabibbo-Kobayashi-Maskawa (CKM) description of flavour mixing and CP violation is also a pillar of the SM, but here the picture is more complex. It is in general very successful, as seen in the left panel of Fig. 2 [3], but there are a number of anomalies. On the one hand, the SM predicted successfully the branching ratio for the rare decay Bs → μ+μ−: BR(Bs → μ+μ−) = 2.8 −0.6 × 10 −9 , (1) measured by the CMS and LHCb Collaborations [4]: see Fig. 3. However, the joint CMS and LHCb analysis [4] also has an suggestion of a Bd → μ+μ− signal that is considerably larger than the SM prediction (which is an ironclad prediction also of models with minimal flavour violation (MFV), including many SUSY scenarios): BR(Bd → μ+μ−) = 3.9 −1.4 × 10 −10 , (2) ar X iv :1 50 1. 05 41 8v 1 [ he pph ] 2 2 Ja n 20 15