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$^{-1}$.
Highlights
In this article, we extend previous works in this topic in three ways
We demonstrate that flavour-changing neutral currents in the top sector, mediated by leptophilic scalars at the electroweak scale, can arise in scenarios of new physics, and in particular in composite Higgs models
Using an effective field theory approach, we have shown that, in models of new physics with light pseudo-scalar singlet degrees of freedom S, new top flavor-changing neutral currents (FCNCs) arise
Summary
We extend previous works in this topic in three ways. First, we consider the rare top decay t → Sq, S → + − including both light leptons and taus. The longitudinal component of the missing neutrino four-momentum (pν) is reconstructed by demanding m2W = (p + pν)2, where p is the four-momentum of the lepton not coming from the scalar decay and mW = 81.2 GeV is our reference value for the W boson mass. We show the distributions of the scalar and top reconstructed masses for two signal benchmark points and for the relevant background components in figure 3.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
