Next-to-leading order QCD corrections to $t\bar t\gamma$ production at   the 7 TeV LHC
  We present the theoretical predictions including the complete next-to-leading order (NLO) QCD corrections to the top-quark pair production in association with a photon at the LHC with center-of-mass system energy of $7 {\rm TeV}$. The uncertainties of the leading order (LO) and NLO QCD corrected cross sections due to the renormalization/factorization scale, and the distributions of the transverse momenta of final top-quark and photon are studied. Moreover, we provide the numerical results of the LO, NLO QCD corrected cross sections and the corresponding $K$-factors with different photon transverse momentum cuts. We also discuss the impact of QCD corrections to the \ppttga in case of there existing the exotic top-quark with an electric charge of $-4e/3$ at the $7 {\rm TeV}$ LHC. 
Duan Peng-Fei, Zhang Ren-You, Ma Wen-Gan, Han Liang, Guo Lei, and Wang   Shao-Ming
hep-ph hep-ex