Fermionic decay of light charged pseudoscalar in Georgi Machacek model

TL;DR

This paper investigates the fermionic decay modes of light charged pseudoscalars in the Georgi-Machacek model, using LHC data to constrain model parameters, especially the triplet vev, based on observed decay channels.

Contribution

It provides the first detailed analysis of fermionic decay channels of light charged pseudoscalars in the GM model using recent LHC data, setting bounds on the triplet vev.

Findings

ATLAS data constrains triplet vev for pseudoscalar mass below 160 GeV.

Fermionic decay channels $cs$ and $ au u$ are crucial for low mass charged pseudoscalars.

More stringent bounds on model parameters are derived from observed decay channels.

Abstract

The Georgi Machacek (GM) model is a triplet extension of the scalar sector of the Standard Model (SM) containing charged and neutral scalars and pseudoscalars with alluring phenomenology. The CMS and ATLAS collaborations of the LHC at $\sqrt{s}=13$ TeV already searched for various decays of the charged Higgs boson in low as well as high mass region. The low mass charged Higgs are produced by the decay of top quarks or antiquarks. $H^{\pm}\rightarrow \tau\nu,\, cs$ are the main fermionic decay channels of light charged scalars or pseudoscalars. For low mass region of the charged pseudoscalars, the triplet vev is restricted from above from the indirect search coming from the $b\rightarrow s \gamma$ decay. Here, I consider the observed data from the ATLAS and CMS both for the light charged Higgs decaying into $cs$ and $\tau\nu$. The ATLAS data observed for $H^{\pm}\rightarrow \tau\nu$ offers a more stringent bound on $v_2$ for GM model pseudoscalar mass below $160$ GeV.