Bounds and Decays of New Heavy Vector-like Top Partners

TL;DR

This paper analyzes the properties, decay modes, and detection prospects of new heavy vector-like top partners at the LHC, highlighting their decay channels, bounds, and potential signatures for different representations.

Contribution

It provides a comprehensive study of the decay patterns and phenomenology of vector-like top partners, including bounds, decay modes, and implications for LHC searches.

Findings

Tree-level decays mainly to Wb, Z, Higgs plus top

Loop-induced radiative decays are small but detectable

Different representations can be distinguished at the LHC

Abstract

We study the phenomenology of new heavy vector-like fermions that couple to the third generation quarks via Yukawa interactions, covering all the allowed representations under the standard model gauge groups. We first review tree and loop level bounds on these states. We then discuss tree level decays and loop-induced decays to photon or gluon plus top. The main decays at tree level are to W b and/or Z and Higgs plus top via the new Yukawa couplings. The radiative loop decays turn out to be quite close to the naive estimate: in all cases, in the allowed perturbative parameter space, the branching ratios are mildly sensitive on the new Yukawa couplings and small. We therefore conclude that the new states can be observed at the LHC and that the tree level decays can allow to distinguish the different representations. Moreover, the observation of the radiative decays at the LHC would suggest a large Yukawa coupling in the non-perturbative regime.