QCD analysis of polarized deep-inelastic scattering data and parton distributions

Abstract

In this talk results from a new QCD analysis in leading (LO) and next-toleading (NLO) order are presented. New parametrizations of the polarized quark and gluon densities are derived together with parametrizations of their fully correlated 1σ error bands. Furthermore the value of α s (M 2 Z ) is determined. Finally a number of low moments of the polarized parton densities are compared with results from lattice simulations. All details of the analysis are given in Ref. [1].

Spin asymmetries in squark and gluino production at polarized hadron colliders

“…They parametrise the probability of finding partons inside the nucleon having their spin aligned or anti-aligned to the nucleon spin and are obtained from a global fit [7][8][9][10][11][12] to spin asymmetries in polarized lepton-hadron and hadron-hadron collisions. They can be used to predict cross sections in collisions of hadrons with fixed spin orientation.…”

QCD spin physics: Status and prospects for relativistic heavy-ion collider

“…5 shows the latest results on the flavor separation by HERMES [21], obtained from their LO Monte-Carlo code based "purity" analysis. Within the still fairly large uncertainties, they are not inconsistent with the large negative polarization of ∆ū = ∆d = ∆s in the sea that has been implemented in many determinations of polarized parton distributions from inclusive DIS data [7,8] (see curves in Fig. 5).…”

“…The gluon density affects the Q 2 -evolution of the structure function g 1 (x, Q 2 ), but the limited lever arm in Q 2 available so far has left ∆g virtually unconstrained [7][8][9]. One way to access ∆g in lepton-nucleon scattering is therefore to look at a less inclusive final state that is particularly sensitive to gluons in the initial state.…”

Light-flavor sea-quark distributions in the nucleon in the SU(3) chiral quark soliton model. I. Phenomenological predictions

“…9 Now, turning to the spin-dependent distribution functions, the quality of the presently available semi-inclusive data is rather poor, so that the analyses are mainly limited to the inclusive DIS data alone. (There exist some combined analyses of inclusive and semiinclusive polarized DIS data [48], [49], [50].) This forces them to introduce several simplifying assumptions in the fittings.…”