UNIFIED DESCRIPTION OF THE NON − SINGLET SPIN DEPENDENT STRUCTURE FUNCTION g 1 INCORPORATING ALTARELLI - PARISI EVOLUTION AND THE DOUBLE LOGARITHMIC ln 2 ( 1 / x ) EFFECTS AT LOW x
نویسنده
چکیده
A unified equation for the non-singlet spin dependent structure function gns 1 (x,Q 2) = g 1(x,Q 2) − gn 1 (x,Q2) which incorporates the complete leading order Altarelli-Parisi evolution at finite x and double logarithmic ln2(1/x) effects at x → 0 is formulated. This equation is solved assuming simple phenomenological parametrisation of the non-perturbative part of the structure function. Reasonable agreement is obtained with the recent data obtained by the Spin Muon Collaboration. Predictions for the small x behaviour of gns 1 (x,Q 2) in the kinematical range which may be relevant for the possible HERA measurements are given. The contribution to the Bjorken sum coming from the region of very small values of x is quantified. Extrapolation of g1(x,Q 2) to the region of small x and small Q2 is also discussed.
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