Photons in the proton: implications for the LHC
Richard Ball (The Higgs Centre for Theoretical Physics, University of Edinburgh, JCMB, KB, Mayfield Rd, Edinburgh, EH9 3JZ, Scotland); Andrea Barontini (Tif Lab, Dipartimento di Fisica, Università di Milano and INFN, Sezione di Milano, Via Celoria 16, Milan, 20133, Italy); Alessandro Candido (CERN, Theoretical Physics Department, Geneva 23, 1211, Switzerland, Tif Lab, Dipartimento di Fisica, Università di Milano and INFN, Sezione di Milano, Via Celoria 16, Milan, 20133, Italy); Stefano Carrazza (Tif Lab, Dipartimento di Fisica, Università di Milano and INFN, Sezione di Milano, Via Celoria 16, Milan, 20133, Italy); Juan Cruz-Martinez (CERN, Theoretical Physics Department, Geneva 23, 1211, Switzerland); et al - Show all 18 authors
We construct a set of parton distribution functions (PDFs), based on the recent NNPDF4.0 PDF set, that also include a photon PDF. The photon PDF is constructed using the LuxQED formalism, while QED evolution accounting for $${\mathcal {O}}\left( \alpha \right) $$ , $${\mathcal {O}}\left( \alpha \alpha _s\right) $$ , and $${\mathcal {O}}\left( \alpha ^2\right) $$ corrections is implemented and benchmarked by means of the EKO code. We investigate the impact of QED effects on NNPDF4.0, and compare our results both to our previous NNPDF3.1QED PDF set and to other recent PDF sets that include the photon. We assess the impact of photon-initiated processes and electroweak corrections on a variety of representative LHC processes, and find that they can reach the 5% level in vector boson pair production at large invariant mass.
