7–11 Apr 2008
University College London
Europe/Zurich timezone

Systematic Analysis of Scaling Properties in Deep Inelastic Scattering

8 Apr 2008, 15:00
20m
Massey (University College London)

Massey

University College London

Gower Street, London, United Kingdom WC1E 6BT
Structure Functions Structure Functions Working Group

Speaker

Prof. Christophe Royon

Description

Using the ``Quality Factor'' (QF) method, we analyse the scaling properties of deep-inelastic processes cross-sections at HERA for $x<10^{-2}.$ We look for scaling formulae of the form $\sigma ^{\gamma^*p}(\tau),$ where $\tau (L\!=\!\log Q^2,Y)$ is a scaling variable proposed in the literature and suggested by the asymptotic properties of QCD evolution equations with rapidity $Y$. We consider four cases: ``Fixed Coupling'', corresponding to the original geometric scaling proposal and motivated by the asymptotic properties of the Balitsky-Kovchegov (BK) equation with {\it fixed} QCD coupling constant, two versions ``Running Coupling I,II'' of the scaling suggested by the BK equation with {\it running} coupling, and ``Diffusive Scaling'' suggested by the QCD evolution equation with Pomeron loops. The Quality Factors, quantifying the phenomenological validity of the candidate scaling variables, are fitted on the total and DVCS cross-section data and predictions are made for the elastic vector-meson and for the diffractive cross-sections at fixed small $x_{\cal P}$ or $\beta.$The first three scaling formulae have comparably good QF while the fourth one is disfavored. Parametrizing non-asymptotic contributions gives a significant improvement of the ``Running Coupling II'' scaling.

Primary author

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