Abstract

One of the missing keys in the present understanding of the spin structure of the nucleon is the contribution from the gluons: the so-called gluon polarization. This quantity can be determined in deep inelastic scattering (DIS) through the photon–gluon fusion process, in which two analysis methods may be used: (i) identifying open charm events or (ii) selecting events with high-transverse-momentum (high-pT) hadrons. The data used in the present work were collected in the COMPASS experiment, where a 160 GeV/c naturally polarized muon beam, impinging on a polarized nucleon fixed target, is used. Preliminary results for the gluon polarization from high-pT and open charm analyses are presented. The gluon polarization result for high-pT hadrons is divided, for the first time, into three statistically independent measurements at leading order (LO) in quantum chromodynamic (QCD). The result from open charm analysis is obtained at LO and next-to-leading order in QCD. In both analyses a new weighted method based on a neural network approach is used.

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