The 125 GeV boson: A composite scalar?

TL;DR

This paper explores the possibility that the 125 GeV boson is a composite scalar generated by a non-Abelian gauge theory, analyzing how its mass depends on the gauge group and fermion representations using the Bethe-Salpeter equation.

Contribution

It provides a detailed calculation of the composite scalar mass in a non-Abelian gauge theory framework, considering various gauge groups and fermion representations, and assesses the likelihood of such a scalar being light.

Findings

Light composite scalar only for specific fermion numbers in fundamental representation.

Small gauge groups with adjoint fermions are unlikely to produce such a light scalar.

The scalar mass depends critically on the gauge group and fermion content.

Abstract

Assuming that the 125 GeV particle observed at the LHC is a composite scalar and responsible for the electroweak gauge symmetry breaking, we consider the possibility that the bound state is generated by a non-Abelian gauge theory with dynamically generated gauge boson masses and a specific chiral symmetry breaking dynamics motivated by confinement. The scalar mass is computed with the use of the Bethe-Salpeter equation and its normalization condition as a function of the SU(N) group and the respective fermionic representation. If the fermions that form the composite state are in the fundamental representation of the SU(N) group, we can generate such light boson only for one specific number of fermions for each group. In the case of small groups, like SU(2) to SU(5), and two fermions in the adjoint representation we find that is quite improbable to generate such light composite scalar.