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 $fb^{-1}$ 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 ${\cal B}R(t\rightarrow u γ) < 1.27%$, ${\cal B}R(t\rightarrow u Z) < 0.8% $, ${\cal B}R(t\rightarrow u g) < 1.02% $ and ${\cal B}R(t\rightarrow u H) < 4.21% $. The sensitivity of future searches in the same-sign top quark channel is also presented.