Nucleon longitudinal spin structure at COMPASS

TL;DR

This paper reports on the measurement of the nucleon spin structure at COMPASS, focusing on gluon polarization and quark flavor decomposition through deep inelastic muon-deuteron scattering, with results from initial data and future projections.

Contribution

It introduces new measurements of gluon polarization and quark flavor separation using semi-inclusive deep inelastic scattering at COMPASS.

Findings

Initial measurements of gluon polarization ($G/G$)

Flavor decomposition of quark helicity distributions

Projected uncertainties for upcoming data

Abstract

The nucleon spin structure is studied at COMPASS via the measurement of the spin dependent properties of deep inelastic muon-deuteron scattering. Both inclusive and semi-inclusive observables are investigated, with the emphasis put on the latter. This allows to access, in particular, the gluon polarization ($\Delta G/G$) and the flavor decomposition of the quark helicity distributions. Results from measurements with longitudinal target polarization are presented, as well as uncertainties expected from the first 3 years of data taking.