Azimuthal Asymmetries in Unpolarised Semi-Inclusive DIS at COMPASS
Abstract
In semi-inclusive deep inelastic scattering (SIDIS) the non-zero transverse momentum of partons induces azimuthal dependence of the cross-section. For unpolarised nucleon, three azimuthal modulations that can be related to different combinations of twist-two or higher twist transverse momentum dependent PDFs and fragmentation functions arise: the so-called Cahn effect reflected in modulation, the term related to the Boer--Mulders PDF and twist-three effect known as beam-spin asymmetry. In 2016 and 2017, the COMPASS experiment at CERN collected a large sample of SIDIS events using a longitudinally polarised 160~GeV/ muon beam scattering on a liquid hydrogen target. Amplitudes of the aforementioned azimuthal modulations have been extracted from part of the data. A new procedure has been developed to subtract a background coming from the decay of diffractively produced vector mesons. The results presented in this talk qualitatively agree with earlier COMPASS results obtained with an isoscalar target.
Keywords
Cite
@article{arxiv.2201.05205,
title = {Azimuthal Asymmetries in Unpolarised Semi-Inclusive DIS at COMPASS},
author = {Jan Matousek},
journal= {arXiv preprint arXiv:2201.05205},
year = {2026}
}
Comments
Proceedings of the 24th International Spin Symposium (SPIN 2021), Matsue, Shimane prefecture, Japan in October 18-22, 2021 5 pages, 7 figures