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The Deuteron Spin-dependent Structure Function g1d and its First Moment

The COMPASS Collaboration, V. Yu. Alexakhin

Abstract

We present a measurement of the deuteron spin-dependent structure function g1d based on the data collected by the COMPASS experiment at CERN during the years 2002-2004. The data provide an accurate evaluation for Gamma_1^d, the first moment of g1d(x), and for the matrix element of the singlet axial current, a0. The results of QCD fits in the next to leading order (NLO) on all g1 deep inelastic scattering data are also presented. They provide two solutions with the gluon spin distribution function Delta G positive or negative, which describe the data equally well. In both cases, at Q^2 = 3 (GeV/c)^2 the first moment of Delta G is found to be of the order of 0.2 - 0.3 in absolute value.

The Deuteron Spin-dependent Structure Function g1d and its First Moment

Abstract

We present a measurement of the deuteron spin-dependent structure function g1d based on the data collected by the COMPASS experiment at CERN during the years 2002-2004. The data provide an accurate evaluation for Gamma_1^d, the first moment of g1d(x), and for the matrix element of the singlet axial current, a0. The results of QCD fits in the next to leading order (NLO) on all g1 deep inelastic scattering data are also presented. They provide two solutions with the gluon spin distribution function Delta G positive or negative, which describe the data equally well. In both cases, at Q^2 = 3 (GeV/c)^2 the first moment of Delta G is found to be of the order of 0.2 - 0.3 in absolute value.

Paper Structure

This paper contains 1 section, 20 equations, 3 figures, 4 tables.

Table of Contents

  1. Acknowledgements

Figures (3)

  • Figure 1: Fraction of inclusive, semi-inclusive, and calorimetric triggers as a function of $x$. Events are counted with the weight they carry in the asymmetry calculation.
  • Figure 2: Difference between asymmetries for inclusive and hadronic Monte Carlo events in the kinematic range covered by the purely calorimetric trigger.
  • Figure :