GMCALC: a calculator for the Georgi-Machacek model

TL;DR

GMCALC is a FORTRAN software tool that calculates particle spectra, couplings, and decay properties in the Georgi-Machacek model, aiding theoretical and phenomenological studies of this extended Higgs sector.

Contribution

It provides a comprehensive, self-contained calculator for the Georgi-Machacek model, including spectrum, couplings, constraints, and MadGraph compatibility, which was not previously available.

Findings

Calculates particle spectrum and couplings in the model

Checks theoretical and experimental constraints

Generates input files for simulation tools

Abstract

The Georgi-Machacek model adds scalar triplets to the Standard Model Higgs sector in such a way as to preserve custodial SU(2) symmetry in the scalar potential. This allows the triplets to have a non-negligible vacuum expectation value while satisfying constraints from the rho parameter. Depending on the parameters, the 125~GeV neutral Higgs particle can have couplings to WW and ZZ larger than in the Standard Model due to mixing with the triplets. The model also contains singly- and doubly-charged Higgs particles that couple to vector boson pairs at tree level (WZ and like-sign WW, respectively). GMCALC is a self-contained FORTRAN program that, given a set of input parameters, calculates the particle spectrum and tree-level couplings in the Georgi-Machacek model, checks theoretical and indirect constraints, and computes the branching ratios and total widths of the scalars. It also generates a param_card.dat file for MadGraph5 to be used with the corresponding FeynRules model implementation.