Hard photons in hadroproduction of top quarks with realistic final states

We present a complete description of top quark pair production in association with a hard photon in the dilepton channel. Our calculation is accurate to NLO in QCD. It is based on matrix elements for e+e production and includes all resonant and non- resonant diagrams, interferences, and o ff - shell e ff ects of the top quarks and the W gauge bosons. This calculation constitutes the fi rst full computation for top quark pair production with a fi nal state photon in hadronic collisions at NLO in QCD. Numerical results for total and di ff erential cross sections are presented for the LHC at a centre- of- mass energy of ps = 13TeV. For a few observables relevant for new physics searches, beyond some kinematic bounds, we observe shape distortions of more than 100%. In addition, we con fi rm that the size of the top quark o ff - shell e ff ects for the total cross section is consistent with the expected uncertainties of the narrow width approximation. Results presented here are not only relevant for beyond the Standard Model physics searches but also important for precise measurements of the top- quark fi ducial cross sections and top- quark properties at the LHC.