Novel flavour-changing neutral currents in the top quark sector

TL;DR

This paper explores new flavor-changing neutral currents involving the top quark mediated by leptophilic scalars, highlighting their potential detectability at the LHC and their weak current experimental constraints.

Contribution

It introduces a novel class of flavor-changing neutral currents in the top sector mediated by leptophilic scalars and assesses their experimental reach at the LHC.

Findings

Current experiments poorly constrain these interactions.

LHC can probe cut-off scales up to ~90 TeV.

Dedicated analyses show promising detection prospects.

Abstract

We demonstrate that flavour-changing neutral currents in the top sector, mediated by leptophilic scalars at the electroweak scale, can easily arise in scenarios of new physics, and in particular in composite Higgs models. We moreover show that such interactions are poorly constrained by current experiments, while they can be searched for at the LHC in rare top decays and, more generally, in the channels $pp\to tS(S)+j$, with $S\to\ell^+\ell^-$. We provide dedicated analyses in this respect, obtaining that cut-off scales as large as $\Lambda\sim$ 90 TeV can be probed with an integrated luminosity of $\mathcal{L} = 150$ fb$^{-1}$.