Search for a lighter neutral custodial fiveplet scalar in the Georgi-Machacek model

TL;DR

This paper investigates the potential to detect a lighter neutral fiveplet scalar in the Georgi-Machacek model using recent LHC data, proposing new parameter constraints and analyzing the model's phenomenology.

Contribution

It introduces a new set of constrained parameters for the GM model to efficiently generate events and compares the production of the scalar with latest experimental search results.

Findings

Constraints on the GM model parameter space are derived.

Correlations among GM input parameters are identified.

Potential decay channels for discovery are discussed.

Abstract

Many researches from both the theoretical and experimental sides have been performed to search for a new Higgs Boson lighter than the 125 $GeV$ Higgs boson which was discovered at the LHC in 2012. In this paper we explore the possibility of constraining a lighter neutral custodial fiveplet scalar $H_{5}^{0}$ in the Georgi-Machacek (GM) model by the latest results of the search for a lighter Higgs boson decaying into two photons from LHC data. The custodial-singlet mass eigenstate $h$ or $H$ is considered to be the LHC observed 125 $GeV$ Higgs boson. A new set of constrained parameters that is favoured by low-mass $H_{5}^{0}$, is proposed to generate events efficiently. The production of $H_{5}^{0}$ from the scan based on the constrained parameters is compared to the latest results of the search for a lighter Higgs boson decaying into two photons by CMS Collaboration, after the theoretical constraints from GM model and the constraints from all existing relevant experimental measurements including the recent results of the Higgs boson searches from the LHC. The numerical analyses of the surviving GM parameter space are performed. The tendencies and correlations of the GM input parameters from the phenomenological studies are summarized. In addition the discovery potential of other interesting decay channels of this low-mass neutral custodial fiveplet scalar are discussed.