Search for top quark flavour changing neutral currents in same-sign top quark production

Abstract

The presence of the anomalous top quark flavour changing neutral current (FCNC) interactions leads to the production of same-sign top quarks in proton-proton collisions. The results of a search for events with same-sign dileptons and b-jets conducted by CMS collaboration with 10.5 $f{b}^{-1}$ of data collected in pp colisions at $\sqrt{s}=8$ TeV are used to obtain the constraints on the strength of top quark FCNC interactions. The 95 confidence level upper limits on the branching ratios of top quark decays to a light quark $q=u,c$ and a gauge or a Higgs boson are set to be $\mathcal{B}R(t\to u\gamma )<1.27$, $\mathcal{B}R(t\to uZ)<0.8$, $\mathcal{B}R(t\to ug)<1.02$ and $\mathcal{B}R(t\to uH)<4.21$. The sensitivity of future searches in the same-sign top quark channel is also presented.

Comments: typos fixed, Refs. added (published version)