The parton distribution functions of the photon and the structure functionF 2 ? (x, Q 2)

Autor: L. E. Gordon, J. K. Storrow
Rok vydání: 1992
Předmět:
Zdroj: Zeitschrift f�r Physik C Particles and Fields. 56:307-314
ISSN: 1434-6052
0170-9739
DOI: 10.1007/bf01555529
Popis: We present new parametrisations of the parton distribution functions of the photon including the first parametrisation in next-to-leading order QCD. We take into account some recent theoretical considerations pertaining to the gluon content of the photon,g γ. We argue that if an evolution is started at very lowQ 2 and a fit to allF 2 γ data performed with no constraints on the gluon distribution, then physically unreasonable gluon distributions may result. Our results support recent indications thatQ 0 2 ≤1 GeV2 is too low a value from which to start a perturbative evolution. Starting our evolution atQ 0 2 =5.3 GeV2, we evolve up inQ 2 using a modified version of Rossi's Ansatz. The limited lever arm inQ 2 leads to limited sensitivity to the QCD scale parameter Λ, though there is a preference for low values in the 0.1–0.2 GeV range. We also present new parametrisations of the singular asymptotic quark and gluon distribution functions of the photon which we believe are more accurate than those in current use.
Databáze: OpenAIRE
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