Reproducing the Higgs boson data with vector-like quarks

TL;DR

This paper investigates how vector-like quarks can modify Higgs boson signals, potentially explaining deviations from Standard Model predictions and suggesting new particles that could be observed at the LHC.

Contribution

It systematically identifies minimal vector-like quark models that improve Higgs rate fits while satisfying experimental constraints, highlighting exotic charges and phenomenology.

Findings

Large enhancements in diphoton channels due to high-charge VL quarks

Minimal VL quark models can significantly improve Higgs rate fits

Predicted exotic quarks may be observable at the LHC within the TeV scale

Abstract

Vector-Like (VL) quarks arise in the main alternatives to the supersymmetric extensions of the Standard Model (SM). Given the experimental possibility of a 125 GeV Higgs boson with rates significantly different from the SM expectations, it is motivating to study the effects of VL quarks on the Higgs boson cross sections and branching ratios. We perform a systematic search for the minimal field contents and gauge group representations of VL quarks able to significantly improve the fit of the measured Higgs rates, and simultaneously, to satisfy the direct constraints on VL quark masses as well as the electro-weak precision tests. In particular, large enhancements can be achieved in certain diphoton channels - as pointed out by both the ATLAS and CMS Collaborations - optimizing then the Higgs rate fit. This is a consequence of the introduction of VL quarks, with high electric charges of 8/3 or -7/3, which are exchanged in the Higgs-to-diphoton loop. Interestingly, the field contents and formal Higgs couplings obtained here are similar to those of scenarios in warped/composite frameworks arising from different motivations. The various exotic-charge quarks predicted, possibly below the TeV scale, might lead to a rich phenomenology soon at the LHC.