%0 Conference Paper
%A Marukyan, Hrachya
%A HERMES Collaboration
%T Overview of HERMES Results on Longitudinal Spin Asymmetries
%V 37
%I Journal of the Physical Society of Japan
%M PUBDB-2023-00204
%P 1-5
%D 2022
%< Proceedings of the 24th International Spin Symposium (SPIN2021) - Journal of the Physical Society of Japan, 2022. - ISBN 4-89027-150-3 - doi:10.7566/JPSCP.37.020106
%X The HERMES experiment collected a wealth of data using the 27.6 GeV polarized HERA lepton beam and various polarized and unpolarized gaseous targets. This allows for a series of unique measurements of observables sensitive to the multidimensional (spin) structure of the nucleon, in particular semi-inclusive deep-inelastic scattering (SIDIS) measurements, for which the HERMES dual-radiator ring-imaging Cherenkov counter provided final-hadron identification between 2 to 15 GeV for pions, kaons, and (anti)protons.In this contribution, longitudinal single- and double-spin asymmetries in SIDIS will be presented. The azimuthally uniform double-spin asymmetries using longitudinally polarized nucleons constrain the flavor dependence of the quark-spin contribution to the nucleon spin. For a first time, such asymmetries are explored differential in three dimensions in Bjorken-x and in the hadron kinematics z and P<sub>h⊥</sub> (which respectively represent the energy fraction and transverse momentum of the final-state hadron) simultaneously. This approach increases the quark-flavor sensitivity and allows to probe the transverse-momentum dependence of the helicity distribution. The measurement of hadron charge-difference asymmetries allows, under certain simplifying assumptions, the direct extraction of valence-quark polarizations. The azimuthal modulation of this double-spin as well as of the single-(beam)spin asymmetry probe novel quark-gluon-quark correlations through twist-3 distribution and fragmentation functions. Also here, asymmetries are explored in several dimensions. Furthermore, in case of the beam-spin asymmetry, results for electro-produced protons and antiprotons have become available. The beam-spin asymmetries for pions are compared to similar measurements for pions at CLAS and unidentified hadrons at COMPASS.
%B 24th International Spin Symposium
%C 18 Oct 2021 - 22 Oct 2021, Matsue (Japan (Hybrid))
Y2 18 Oct 2021 - 22 Oct 2021
M2 Matsue, Japan (Hybrid)
%F PUB:(DE-HGF)8 ; PUB:(DE-HGF)7
%9 Contribution to a conference proceedingsContribution to a book
%R 10.7566/JPSCP.37.020106
%U https://bib-pubdb1.desy.de/record/491512