Singlet channel scattering in a Composite Higgs model on the lattice

TL;DR

This paper reports the first lattice calculation of singlet channel scattering in a composite Higgs model, revealing a stable singlet state in an $SU(2)$ gauge theory with two fermions, relevant for beyond Standard Model physics.

Contribution

It introduces a novel lattice computation of scattering amplitudes in a non-QCD gauge theory with chiral symmetry breaking relevant for composite Higgs models.

Findings

The lowest flavor singlet state is stable for the studied fermion masses.

The study demonstrates the feasibility of lattice scattering calculations in non-QCD theories.

Results inform the phenomenology of composite Higgs models at the LHC.

Abstract

We present the first calculation of the scattering amplitude in the singlet channel beyond QCD. The calculation is performed in $SU(2)$ gauge theory with $N_f=2$ fundamental Dirac fermions and based on a finite-volume scattering formalism. The theory exhibits a $SU(4) \to Sp(4)$ chiral symmetry breaking pattern that is used to design minimal composite Higgs models currently tested at the LHC. Our results show that, for the range of underlying fermion mass considered, the lowest flavour singlet state is stable.