A natural mechanism for approximate Higgs alignment in the 2HDM
Abstract
The 2HDM possesses a neutral scalar interaction eigenstate whose treelevel properties coincide with the Standard Model (SM) Higgs boson. In light of the LHC Higgs data which suggests that the observed Higgs boson is SMlike, 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 socalled 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 vectorlike 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 finetuning of the model parameters. We then explore the implications of the current LHC bounds on vectorlike top quark partners for the success of our proposed scenario.
 Publication:

Journal of High Energy Physics
 Pub Date:
 May 2021
 DOI:
 10.1007/JHEP05(2021)235
 arXiv:
 arXiv:2011.13159
 Bibcode:
 2021JHEP...05..235D
 Keywords:

 Beyond Standard Model;
 Higgs Physics;
 High Energy Physics  Phenomenology
 EPrint:
 55 pages, 8 figures, 3 tables, and 3 appendices