Searching for New Physics with precision calculations of Higgs properties.

by Johannes Braathen

Thursday 10 Oct 2019, 14:15 → 15:15 Europe/Berlin

313 (Main)

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 discuss the matching of renormalisable couplings between generic theories at one-loop order, motivated by Higgs mass calculations in scenarios with heavy New Physics. In particular, I will present choices of renormalisation schemes and procedures that can simplify the calculation of the matching conditions and the automation of said calculations [1]. 
The second part of the talk will be devoted to the Higgs trilinear coupling. This coupling is especially important as it determines the shape of the Higgs potential, and in turn the nature and strength of the electroweak phase transition (EWPT). At the same time, it is known that, in a variety of BSM models (e.g. with extra scalar doublets or 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, because of non-decoupling effects in the radiative corrections involving the additional scalars. It is then natural to ask by how much two-loop corrections can modify this result, and whether 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 several models with extended scalar sectors.