EW corrections to $t \bar t$ distributions: the photon PDF effect

Understand

In this proceeding we present the impact of the EW corrections on $t \bar t$ distributions focusing on the effect of the photon PDF.

• We use the {\sc NNPDF2.3QED} and {\sc CT14QED} PDF sets, which include the photon PDF.
• We discuss a detailed comparison between the results obtained from these two PDF sets at NLO QCD+EW accuracy for 13 TeV, focusing on the top-quark $p_T$ and the top-quark pair rapidity.
• We point out the differences between these two PDF sets and we show that the rapidity of the top-quark pair can be used in order to constrain the photon PDF predicted by the {\sc NNPDF2.3QED} set.