Composite scalars at the LHC: the Higgs, the Sextet and the Octet

TL;DR

This paper explores a phenomenological model of scalar particles transforming as sextets and octets under QCD, proposing their potential as composite states related to the Higgs and top quark, with implications for LHC searches.

Contribution

It introduces a concrete UV completion based on the SU(4)/Sp(4) coset, detailing the production, detection, and constraints of these scalars at the LHC.

Findings

Set lower mass limits for octet and sextet scalars using 8 TeV data.

Analyzed LHC Run II prospects focusing on same sign leptons.

Identified potential to distinguish sextet signals at 13 TeV.

Abstract

We present a phenomenological theory of scalar particles that transform as a sextet and an octet of QCD interactions. These particles may arise as light bound states of a fundamental dynamics giving rise to a composite Higgs boson and partial compositeness for the top. As a concrete example, we discuss an explicit UV completion based on the SU(4)/Sp(4) coset, where QCD colour is carried by additional fundamental fermions charged under the confining gauge group. Top partners, as well as potentially even lighter coloured scalars, arise as bound states of the coloured fermions. We study production and detection at LHC Run I and II of the octet and sextet, setting lower limits on masses and couplings to Standard Model particles using existing 8 TeV analyses. We finally explore prospects for the ongoing 13 TeV Run II: we focus on final states with two same sign leptons, that have the potential to discriminate the sextet.