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