Physics – High Energy Physics – High Energy Physics - Phenomenology
Scientific paper
2004-04-27
Acta Phys.Polon. B35 (2004) 2215-2240
Physics
High Energy Physics
High Energy Physics - Phenomenology
27 pages, 14 figures, FORTRAN programs available at http://www.fuw.edu.pl/~pjank/param.html
Scientific paper
Radiatively generated, LO quark (u,d,s,c,b) and gluon densities in the real, unpolarized photon, improved in respect to our previous paper, are presented. We perform three global fits to the F_2^gamma data, using the LO DGLAP evolution equation. We improve the treatment of the strong coupling running and used lower values of Lambda_QCD, as we have found that the too high values adopted in the previous work caused the high chi^2 of the fits. In addition to the modified FFNS_CJKL model, referred to as FFNS_CJK 1 we analyse a FFNS_CJK 2 model in which we take into account the resolved-photon heavy-quark contribution. New CJK model with an improved high-x behavior of the F_2^gamma(x,Q^2) is proposed. Finally, in the case of the CJK model we abandon the valence sum rule imposed on the VMD input densities. New fits give chi^2 per degree of freedom about 0.25 better than the old results. All features of the CJKL model, such as the realistic heavy-quark distributions, good description of the LEP data on the Q^2 dependence of the F_2^gamma and on F_2,c^gamma are preserved. Moreover we present results of an analysis of the uncertainties of the CJK parton distributions due to the experimental errors. It is based on the Hessian method used for the proton and very recently applied for the photon by one of us. Parton and structure function parametrizations of the best fits in both FFNS_CJK and CJK approaches are made accessible. For the CJK model we provide also sets of test parametrizations which allow for calculation of uncertainties of any physical value depending on the real photon parton densities.
Cornet Fernando
Jankowski P.
Krawczyk Maria
No associations
LandOfFree
CJK-Improved 5 Flavour LO Parton Distributions in the Real Photon does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with CJK-Improved 5 Flavour LO Parton Distributions in the Real Photon, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and CJK-Improved 5 Flavour LO Parton Distributions in the Real Photon will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-511114