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Leading-order determination of the gluon polarisation from semi-inclusive deep inelastic scattering data

Author
Adolph C. Institute of Physics, University of Erlangen Nuremberg
Finger Miroslav, prof. Ing. DrSc. Faculty of Mathematics and Physics, Charles University in Prague
Finger Michael, M.Sc. CSc. Faculty of Mathematics and Physics, Charles University in Prague, JINR Dubna
Slunečka Miloš, Ing. Faculty of Mathematics and Physics, Charles University in Prague, JINR Dubna
et al.  COMPASS collaboration
Smolík Jan, Mgr. Ph.D. Faculty of Nuclear Sciences and Physical Engineering CTU
Taševský  Marek, Mgr. Ph.D. Institute of Physics ASCR

Year
2017

Scientific journal
European Physical Journal C, 77 (4), 209

Web


Abstract
Using a novel analysis technique, the gluon polarisation in the nucleon is re-evaluated using the longitudinal double-spin asymmetry measured in the cross section of semi-inclusive single-hadron muoproduction with photon virtuality Q(2) > 1 ( GeV/c)(2). The data were obtained by the COMPASS experiment at CERN using a 160 GeV/c polarised muon beam impinging on a polarised (LiD)-Li-6 target. By analysing the full range in hadron transverse momentum p(T), the different pT-dependences of the underlying processes are separated using a neural-network approach. In the absence of pQCD calculations at next-to-leading order in the selected kinematic domain, the gluon polarisation Delta g/g is evaluated at leading order in pQCD at a hard scale of mu(2) = < Q(2) > = 3( GeV/c)(2). It is determined in three intervals of the nucleon momentum fraction carried by gluons, x(g), covering the range 0.04< x(g)< 0.28 and does not exhibit a significant dependence on xg. The average over the three intervals, < Delta g/g > = 0.113 +/- 0.038(stat) +/- 0.036( syst) at < x(g) > approximate to 0.10, suggests that the gluon polarisation is positive in the measured x(g) range.

Cite article as:
C. Adolph, M. Finger, M. Finger, M. Slunečka, . et al., J. Smolík, M. Taševský , "Leading-order determination of the gluon polarisation from semi-inclusive deep inelastic scattering data", European Physical Journal C, 77 (4), 209 (2017)