Jul 20 – 27, 2011
Alpes Congrès - Alpexpo
Europe/Paris timezone

Quantifying the impact of collider isolated photon data on global PDF fits

Jul 21, 2011, 3:30 PM
Bayard (Alpes Congrès - Alpexpo)


Alpes Congrès - Alpexpo

Parallel session talk QCD QCD


Prof. David d'Enterria (CERN)


Isolated prompt photon production in proton-(anti)proton collisions proceeds mostly through quark-gluon Compton scattering [1] and has been proposed since long to directly constrain the gluon distribution in the proton. There exist 25 pT-differential measurements of isolated photon production at collider energies in the range sqrt(s)=0.2-7 TeV which are well reproduced by next-to-leading-order (NLO) perturbative QCD predictions, yet the photon data have not been included in global parton distribution functions (PDF) fits since more than 10 years. We present a quantitative study of the impact of including these data sets into global PDF fits based on the JETPHOX NLO code [2] supplemented with the NNPDF2.1 parton densities [3]. By running over hundreds of PDF replicas and using the NNPDF reweighting technique [4] we quantify the additional constraints that all these data (and coming LHC measurements) will impose on the gluon distribution of the proton. [1] R.Ichou and D.d'Enterria, Phys.Rev.D82(2010)014015;arXiv:1005.4529 [2] S.Catani, M.Fontannaz, J.P.Guillet, E.Pilon, JHEP 0205(2002)028;hep-ph/0204023 [3] R.D. Ball et al. [NNPDF Coll.], Nucl.Phys.B849(2011)296; arXiv:1101.1300 [4] R.D. Ball et al. [NNPDF Coll.], Nucl.Phys.B849(2011)112; arXiv:1012.0836

Primary author

Prof. David d'Enterria (CERN)

Presentation materials