Vector-like quarks with a scalar triplet

TL;DR

This paper explores a minimal extension of the Standard Model incorporating a real scalar triplet and a vector-like quark, aiming to address Higgs mass corrections and proposing new decay channels for collider searches.

Contribution

It introduces a novel model with non-renormalizable interactions that cancel top quark divergences and predicts new decay modes for vector-like quarks, connecting collider and low-energy constraints.

Findings

Heavy vector-like top quarks as light as 650 GeV are allowed by current data.

New decay modes involving the scalar triplet can be probed at the LHC.

The model links naturalness, dark matter, and collider phenomenology.

Abstract

We study a minimal extension to the Standard Model with an additional real scalar triplet, $\Sigma$, and a single vector-like quark, $T$. This class of models appear naturally in extensions of the Littlest Higgs model that incorporate dark matter without the need of $T$-parity. We assume the limit that the triplet does not develop a vacuum expectation value and that all dimension five operators coupling the triplet to Standard Model fields and the vector-like quarks are characterized by the scale $\Lambda$ at which we expect new physics to arise. We introduce new non-renormalizable interactions between the new scalar sector and fermion sector that allow mixing between the Standard Model third generation up-type quark and the vector-like quark in a way that leads to the cancellation of the leading quadratic divergences to the one-loop corrections from the top quark to the mass of the Higgs boson. Within this framework, new decay modes of the vector-like quark to the real scalar triplet and SM particles arise and bring forth an opportunity to probe this model with existing and future LHC data. We contrast constraints from direct colliders searches with low energy precision measurements and find that heavy vector-like top quarks with a mass as low as $650$ GeV are consistent with current experimental constraints in models where new physics arises at scales below $2$ TeV.