A natural mechanism for approximate Higgs alignment in the 2HDM

The 2HDM possesses a neutral scalar interaction eigenstate whose tree-level properties coincide with the Standard Model (SM) Higgs boson. In light of the LHC Higgs data which suggests that the observed Higgs boson is SM-like, it follows that the mixing of the SM Higgs interaction eigenstate with the other neutral scalar interaction eigenstates of the 2HDM should be suppressed, corresponding to the so-called Higgs alignment limit. The exact Higgs alignment limit can arise naturally due to a global symmetry of the scalar potential. If this symmetry is softly broken, then the Higgs alignment limit becomes approximate (although still potentially consistent with the current LHC Higgs data). In this paper, we obtain the approximate Higgs alignment suggested by the LHC Higgs data as a consequence of a softly broken global symmetry of the Higgs Lagrangian. However, this can only be accomplished if the Yukawa sector of the theory is extended. We propose an extended 2HDM with vector-like top quark partners, where explicit mass terms in the top sector provide the source of the soft symmetry breaking of a generalized CP symmetry. In this way, we can realize approximate Higgs alignment without a significant fine-tuning of the model parameters. We then explore the implications of the current LHC bounds on vector-like top quark partners for the success of our proposed scenario.

Single production of vector-like top partner in the Wb channel at eγ collision in the LHT model

In the framework of the littlest Higgs Model with T-parity (LHT), we investigate the single production of vector-like top partner [Formula: see text] decaying to [Formula: see text] in the leptonic channel at the high energy [Formula: see text] collision. We utilize the polarized electron beam and photon beam to enhance the signal and propose a search strategy by performing a detector simulation. On the basis of the current limits from the precision electroweak data and Higgs data, we find that the top partner mass can be excluded up to 1350 (1380) GeV with integrated luminosity of 1000 fb[Formula: see text] and 1400 (1470) GeV with integrated luminosity of 3000 fb[Formula: see text] for the [Formula: see text] TeV (2.4 TeV) at the [Formula: see text] level. If the center-of-mass energy can be improved to 3.0 TeV, the limits on the top partner mass will reach 1450 (1550) GeV with integrated luminosities of 1000 (3000) fb[Formula: see text].

The Higgs properties in the MSSM after the LHC Run-2

We scrutinize the parameter space of the SM-like Higgs boson in the minimal supersymmetric standard model (MSSM) under current experimental constraints. The constraints are from (i) the precision electroweak data and various flavor observables; (ii) the direct 22 separate ATLAS searches in Run-1; (iii) the latest LHC Run-2 Higgs data and tri-lepton search of electroweakinos. We perform a scan over the parameter space and find that the Run-2 data can further exclude a part of parameter space. For the property of the SM-like Higgs boson, its gauge couplings further approach to the SM values with a deviation below 0.1%, while its Yukawa couplings [Formula: see text] and [Formula: see text] can still sizably differ from the SM predictions by several tens percent.

Composite Higgs Models after Run 2

We assess the status of models in which Higgs is a composite pseudo-Nambu Goldstone boson, in the light of the latest 13 TeV Run 2 Higgs data. Drawing from the extensive Composite Higgs literature, we collect together predictions for the modified couplings of Higgs, in particular examining the different predictions for κV and κF. Despite the variety and increasing complexity of models on the market, we point out that many independent models make identical predictions for these couplings. We then look into further corrections induced by tree-level effects such as mass-mixing and singlet VEVs. We then investigate the compatibility of different models with the data, combining Run 1 and recent Run 2 LHC data. We obtain a robust limit on the scale f of 600 GeV, with stronger limits for different choices of fermion embeddings. We also discuss how a deficit in a Higgs channel could pinpoint the type of Composite Higgs model responsible for it.