Implications of a High-Mass Diphoton Resonance for Heavy Quark Searches

TL;DR

This paper explores how a high-mass diphoton resonance affects searches for heavy vector-like quarks, proposing new detection channels at the LHC and analyzing how to distinguish these decays from standard modes.

Contribution

It introduces a novel search strategy for vector-like top partners via scalar-mediated decay channels at the 13 TeV LHC, considering enhanced diphoton branching ratios.

Findings

A singlet top partner can be detected through its decay into a scalar and a quark.

Conventional heavy quark searches can be adapted to detect these new decay modes.

Kinematic distributions can help distinguish between different heavy quark decay processes.

Abstract

Heavy vector-like quarks coupled to a scalar $S$ will induce a coupling of this scalar to gluons and possibly (if electrically charged) photons. The decay of the heavy quark into $Sq$, with $q$ being a Standard Model quark, provides, if kinematically allowed, new channels for heavy quark searches. Inspired by naturalness considerations, we consider the case of a vector-like partner of the top quark. For illustration, we show that a singlet partner can be searched for at the 13$\,$TeV LHC through its decay into a scalar resonance in the $2\gamma+\ell + X$ final states, especially if the diphoton branching ratio of the scalar $S$ is further enhanced by the contribution of non coloured particles. We then show that conventional heavy quark searches are also sensitive to this new decay mode, when $S$ decays hadronically, by slightly tightening the current selection cuts. Finally, we comment about the possibility of disentangling, by scrutinising appropriate kinematic distributions, heavy quark decays to $St$ from other standard decay modes.