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A new 5 Flavour LO Analysis and Parametrization of Parton Distributions in the Real Photon
New, radiatively generated, LO quark (u,d,s,c,b) and gluon densities in a real, unpolarized photon are presented. We perform a global 3 parameter fit, based on LO DGLAP evolution equations, to all available data for the structure function F2^gamma(x,Q^2). We adopt a new theoretical approach called A...
Autores principales: | , , , |
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Lenguaje: | eng |
Publicado: |
2002
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Materias: | |
Acceso en línea: | https://dx.doi.org/10.1103/PhysRevD.68.014010 http://cds.cern.ch/record/596343 |
Sumario: | New, radiatively generated, LO quark (u,d,s,c,b) and gluon densities in a real, unpolarized photon are presented. We perform a global 3 parameter fit, based on LO DGLAP evolution equations, to all available data for the structure function F2^gamma(x,Q^2). We adopt a new theoretical approach called ACOT(chi), originally introduced for the proton, to deal with the heavy-quark thresholds. This defines our basic model (CJKL model) which gives a very good description of the experimental data on F2^gamma(x,Q^2), for both Q^2 and x dependences. For comparison we perform a standard fit using the Fixed Flavour-Number Scheme (FFNS_cjkl model), updated with respect to the previous fits of this type. We show the superiority of the CJKL fit over the FFNS_cjkl one and other LO fits to the F2^gamma(x,Q^2) data. The CJKL model gives also the best description of the LEP data on the Q^2 dependence of the F2^gamma$, averaged over various x-regions, and the F_2,c^gamma, which were not used directly in the fit. Finally, a simple analytic parametrization of the resulting parton densities obtained in the CJKL model is given. |
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