DESY Theory Seminar

Searching for New Physics with precision calculations of Higgs properties

by Johannes Braathen (U Osaka)

Tuesday, May 28, 2019 from to (Europe/Berlin)
at Bldg. 2A ( SR2 )
The precise study of the Higgs boson properties -- in particular its mass and couplings -- is of the utmost importance for the investigation of BSM models with extended Higgs sectors.
In the first part of this talk, I will present recent work [1] on the matching of renormalisable couplings between generic theories at one-loop order, -- focusing on the scalar quartic and Yukawa couplings -- motivated by Higgs mass calculations in scenarios with heavy New Physics. In particular, I will discuss the different choices of renormalisation schemes and procedures that are possible in this context.
The second part of the presentation will be devoted to the Higgs trilinear coupling, which deserves attention as it determines the shape of the Higgs potential, and in turn the nature of the electroweak phase transition (EWPT). In particular a large deviation of the Higgs trilinear coupling from its SM prediction is necessary for the EWPT to be of strong first order, which is needed for electroweak baryogenesis. At the same time, it is known that, in a variety of BSM models with extended Higgs sectors (e.g. with doublets, singlets, etc.), the value of the Higgs trilinear coupling can deviate significantly -- i.e. by a hundred percent, or more -- from its Standard-Model prediction at one-loop order, because of non-decoupling effects in the radiative corrections involving the additional scalar states. It is then natural to ask if two-loop corrections can modify this result, and whether new large corrections can appear again. With this motivation, I will present new calculations [2] of dominant two-loop corrections to the Higgs trilinear coupling in two models with extended scalar sectors, namely a Two-Higgs-Doublet Model and the Inert Doublet Model.

[1] J.B., M. Goodsell, and P. Slavich, arXiv:1810.09388
[2] J.B. and S. Kanemura, arXiv:1903.05417