QCD corrections to the production of tt¯γ at the ILC

A precise calculation of the top quark pair production associated with a hard photon is essential for testing the electroweak property of the top quark in the Standard Model (SM). We investigate the one-loop QCD corrections to the process e+e−→tt¯γ at the International Linear Collider (ILC), and find that the K-factor can be as large as 1.238 (1.105,1.060) for a center-of-mass energy s=500(800,1500) GeV. The transverse momentum distributions of the top quark and photon are respectively shown at leading order (LO) and next-to-leading order (NLO). Due to the asymmetric rapidity distribution of the top (anti-top) quark, we also study the top quark forward-backward asymmetry (AFBt) in tt¯γ production at NLO, which is found to be 45.82 (55.25,55.89)% for s=500(800,1500) GeV.