# Phenomenology 2014 Symposium

5-7 May 2014
University of Pittsburgh
US/Eastern timezone

## The decoupling limit in the Georgi-Machacek model

5 May 2014, 17:15
15m
Benedum Hall G30 (University of Pittsburgh)

### Speaker

Kathryn (Katy) Hartling (C)

### Description

We study the most general scalar potential of the Georgi-Machacek model, which adds isospin-triplet scalars to the Standard Model (SM). We show that this model possesses a decoupling limit, in which the predominantly-triplet states become heavy and degenerate while the couplings of the remaining light neutral scalar approach those of the SM Higgs boson. We find that the SM-like Higgs boson couplings to fermion pairs and gauge boson pairs can deviate from their SM values by corrections as large as $\mathcal{O}(v^2/M_{\rm new}^2)$, where $v$ is the SM Higgs vacuum expectation value and $M_{\rm new}$ is the mass scale of the predominantly-triplet states. In particular, the SM-like Higgs boson couplings to $W$ and $Z$ boson pairs can decouple much more slowly than in two Higgs doublet models. As such, precision measurements of these couplings may provide an effective method of distinguishing the Georgi-Machacek model from two Higgs doublet models.

### Primary authors

Prof. Heather Logan (Carleton U.) Kathryn (Katy) Hartling (C) Kunal Kumar (Carleton University)

 Slides