Modelling vector-like quarks in partial compositeness framework

Abstract

Composite Higgs models, together with partial compositeness, predict the existence of new scalars and vector-like quarks (partners) at and above the TeV scale. Generically, the presence of these additional scalars opens up new decay topologies for the partners. In this paper we show how to systematically construct the general low energy Lagrangian to capture this feature. We emphasize the specific pattern in the top-partner spectrum arising in this class of models. We then present a concrete realization in the context of the SU(5)/SO(5) coset. We show that the top-partners in this model can have significant branching ratios to the additional scalars and a third generation quark, compared to the usual Standard Model channels. Amongst the most promising signatures at the LHC are final states containing a diphoton resonance along with a top quark.

Phenomenological aspects of composite Higgs scenarios: exotic scalars and vector-like quarks

“…To construct the low energy theory [57,58] involving the pNGBs of the EW sector, the VLQs, and the SM quarks and gauge bosons one must choose a symmetry breaking pattern G/H, VLQs in H irreps, and an embedding of the SM quarks into an irrep of G, see [6,42,[59][60][61] for detailed constructions.…”

“…A detailed description of how all the couplings can be derived, including the VLQ sector, has been given in [61]. For this section we consider the exotic pNGBs to be fermiophobic.…”

Composite dynamics in Sp(2N) gauge theories

“…[26] (but, see also Ref. [27] for the other possibilities), is not the lightest state, as shown in the left panel of Fig. 6.…”

Vacuum misalignment in presence of four-Fermi operators

“…The projector matrices are chosen in such a way that the left handed quark doublet (q L ) is embedded in (2, 2) and the right handed top quark (t R ) in (1, 1) or (1, 3) under the unbroken SU (2) L × SU (2) R subgroup. Detailed constructions of these models can be found in [39].…”