Analytic Approaches to the Evolution of Polarised Parton Distributions at Small $x$

Abstract

The $Q^2$ evolution of polarised parton distributions at small $x$ is studied. Various analytic approximations are critically discussed. We compare the full evolution with that obtained from the leading-pole approximation to the splitting functions, and show that the validity of this approximation depends critically on the $x\to 0$ behaviour of the starting distributions. A new analytic solution which is valid at small $x$ is obtained, and its domain of applicability is discussed.

14 pages, LATeX, 4 figures availabe as .uu-file

References in corpus (5)

• Measurement of the Spin-Dependent Structure Function $g_1(x)$ of the Proton
• Spin-dependent Parton Distributions from Polarized Structure Function Data
• Scale Dependence and Small-x Behaviour of Polarized Parton Distributions
• The Spin Dependence of Diffractive Processes and Implications for the Small $x$ Behaviour of $g_1$ and the Spin Content of the Nucleon
• The small $x$ behaviour of $g_1$

Cited by in corpus (8)

• Polarized Parton Distributions in the Nucleon
• On the analytical approximation to the GLAP evolution at small x and moderate Q^2
• Small- and large-x nucleon spin structure from a global QCD analysis of polarized Parton Distribution Functions
• QCD expectations for the spin structure function $g_1$ in the low $x$ region
• Unified description of the non-singlet spin dependent structure function $g_1$ incorporating Altarelli-Parisi evolution and the double logarithmic $l{n}^2(1/x)$ effects at low $x$
• The Bethe-Heitler Process in Polarized Photon-Nucleon Interactions
• A polarized version of the CCFM equation for gluons
• QCD predictions for spin dependent photonic structure function $g_1^{\gamma }(x,Q^2)$ in the low x region of future linear colliders