CERN Accelerating science

Article
Title	Longitudinal spin structure of the nucleon at COMPASS
Author(s)	Bedfer, Yann (IRFU, Saclay, DPHN)
Collaboration	COMPASS Collaboration
Publication	SISSA, 2019
Number of pages	7
In:	PoS SPIN2018 (2019) 137
In:	23rd International Spin Symposium, Ferrara, Italy, 10 - 14 Sep 2018, pp.137
DOI	10.22323/1.346.0137
Subject category	Particle Physics - Experiment ; Nuclear Physics - Experiment
Accelerator/Facility, Experiment	CERN SPS ; NA58
Abstract	For a large fraction of its already twenty year long existence, the COMPASS collaboration hasstudied the polarised structure of the nucleon via muon-nucleon scattering. This paper summa-rizes the final results obtained in longitudinally polarised DIS, either inclusive or semi-inclusive.For inclusive DIS, these cover the measurements of structure function $g_1$, and the information ex-tracted from them in terms of polarised PDFs (pPDFs) and Bjorken sum rule. From $g_1$ measure-ments alone, combining COMPASS with world data, the quark spin contribution to the nucleonspin is determined to be 0.26 < ∆Σ < 0.36. And from COMPASS data alone, the Bjorken sumrule is verified to 9% accuracy. In semi-inclusive DIS, more information can be gained on the pPDFs of sea quarks and gluons. A selection of our achievements along this line are reported.
Copyright/License	© 2019-2025 The author(s) (License: CC-BY-NC-ND-4.0)

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