Understanding Geometric Scaling at Small x

2002/05/18 by E. Iancu, Iancu, E., K. Itakura +3
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #hep-ph

paper · pdf · doi:10.48550/arxiv.hep-ph/0205198

4 pages, 1 figure, uses moriond.sty, included. Talk presented at the XXXVIIth Rencontres de Moriond "QCD and high energy hadronic interactions", Les Arcs, France, March 16-23, 2002

arxiv created 2002/05/18 · arxiv updated 2009/11/30

Abstract

Geometric scaling is a novel scaling phenomenon observed in deep inelastic scattering at small x: the total virtual photon-proton cross section depends upon the two kinematical variables Q² and x only via their combination Q² R₀²(x), with R₀²(x) ∝ x^λ. At sufficiently low Q², below the saturation scale Q_s²(x) (a few GeV²), this phenomenon finds a natural explanation as a property of the Color Glass Condensate, the high-density matter made of saturated gluons. To explain the experimental observation of geometric scaling up to much higher values of Q², of the order of 100 GeV², we study the solution to the BFKL equation subjected to a saturation boundary condition at Q²∼ Q_s²(x). We find that the scaling extends indeed above the saturation scale, within a window 1 < ln(Q²/Q_s²) << ln(Q_s²/Λ²_{\rm QCD}), which is consistent with phenomenology.

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