Search for anomalous single top quark production in association with a photon

A search for single top quark production through flavor-changing neutral currents in the anomalous $tq\gamma$ vertex is presented in proton-proton collisions at a center-of-mass energy of 8 TeV. The analysis is based on a data-set corresponding to an integrated luminosity of 19.1 fb$^{-1}$ collected with the CMS detector. The search is performed on events with one isolated muon and jets in the final state. No evidence for a signal is observed. Upper limits on the strengths of the anomalous couplings at leading order for vertices involving a top quark, a photon, and another up-like quark are set at $95\%$ confidence level to be $\kappa_{tu\gamma}<0.028$ and $\kappa_{tc\gamma}<0.094$. The corresponding upper bounds on the top quark decay branching ratios are $BR(t\rightarrow u+\gamma)<0.0161\%$ and $BR(t\rightarrow c+\gamma)<0.182\%$.