2001/12/31 by HERMES Collaboration, A. Airapetian, Н. Акопов +98 · 2 citations
Physics and Astronomy · #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #hep-ex
paper · pdf · doi:10.1016/s0370-2693(02)01780-x
published as Phys.Lett.B535:85-92,2002 · PLB accepted version, 6 pages, 4 figures, LaTex (revtex4), corrected typo
arxiv created 2002/04/18 · openalex publication_date 2002/05/01 · arxiv updated 2009/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/01
A single-spin asymmetry in the distribution of exclusively produced pi+ mesons azimuthally around the virtual photon direction relative to the lepton scattering plane has been measured for the first time in deep-inelastic scattering of positrons off longitudinally polarized protons. Integrated over the experimental acceptance, the sin ϕmoment of the polarization asymmetry of the cross section is measured to be -0.18 +/- 0.05 (stat.) +/- 0.02 (syst.). The asymmetry is also studied as a function of the relevant kinematic variables, and its magnitude is found to grow with decreasing x and increasing -t and vanish at t -> tmin (where x is the Bjorken scaling variable and t is the squared four-momentum transferred to the nucleon).