Article

# Measurement of single-spin azimuthal asymmetries in semi-inclusive electroproduction of pions and kaons on a longitudinally polarised deuterium target

[more]
Physikalisches Institut, Universität Erlangen-Nürnberg, 91058 Erlangen, Germany
(Impact Factor: 6.13). 06/2003; 562(2003)(3-4):182-192. DOI: 10.1016/S0370-2693(03)00566-5

ABSTRACT Single-spin asymmetries have been measured for semi-inclusive electroproduction of π+, π−, π0 and K+ mesons in deep-inelastic scattering off a longitudinally polarised deuterium target. The asymmetries appear in the distribution of the hadrons in the azimuthal angle φ around the virtual photon direction, relative to the lepton scattering plane. The corresponding analysing powers in the sinφ moment of the cross section are 0.012±0.002(stat.)±0.002(syst.) for π+, 0.006±0.003(stat.)±0.002(syst.) for π−, 0.021±0.005(stat.)±0.003(syst.) for π0 and 0.013±0.006(stat.)±0.003(syst.) for K+. The sin2φ moments are compatible with zero for all particles.

### Full-text

Available from: L. Lapikás, Apr 30, 2014
0 Followers
·
• Source
##### Article: The COMPASS experiment and the RICH-1 detector
[Hide abstract]
ABSTRACT: The Common Muon and Proton Apparatus for Structure and Spectroscopy (COMPASS) is a new fixed target experiment at the CERN (Conseil Européen pour la Recherche Nucléaire) Super Proton Synchrotron (SPS) with the aim to study hadron structure with polarized muon beams and hadron spectroscopy with hadron beams. The main physics objective of the muon beam physics program is the measurement of the gluon polarization in a longitudinally polarized nucleon. The hadronic program comprises a search for glue balls in the high mass region in exclusive diffractive pion proton scattering, a study of leptonic and semi leptonic decays of charmed hadrons with high statistics and precision and Primakoff scattering with various probes. A detailed investigation of charmed and doubly charmed baryons is performed in a second stage of the experiment. The setup consists of two spectrometers, one for small angle and one for large angle particles, giving a wide angular acceptance for all measurements. Each spectrometer performs full particle identification using one Ring Imaging Cherenkov Counter (RICH), electromagnetic and hadronic calorimetry and muon detection. A high momentum resolution is obtained by using highly precise tracking with silicon detectors, gaseous strip detectors and drift tubes. The measurements are performed with high intensity beams allowing to collect the needed statistics. The key-detector for particle identification is the RICH-1, which is a technological challenge in terms of photon detection and radiator gas supply. The COMPASS setup is presented with special focus on the radiator gas preparation and operational aspects of the gas system. Some first results on D meson analysis are presented.
• Source
##### Article: Single spin asymmetries in semi-inclusive deep inelastic scattering
[Hide abstract]
ABSTRACT: In this talk I want to illustrate the many possibilities for studying the structure of hadrons in hard scattering processes by giving a number of examples involving increasing complexity in the demands for particle polarization, particle identification or polarimetry. In particular the single spin asymmetries will be discussed. The measurements discussed in this talk are restricted to lepton-hadron scattering, but can be found in various other hard processes such as Drell-Yan scattering or $e^+e^-$-annihilation.
Acta Physica Polonica Series B 04/1998; · 0.85 Impact Factor
• Source
##### Article: Collins effect and single spin azimuthal asymmetriesin the HERMES and COMPASS experiments
[Hide abstract]
ABSTRACT: Predictions are made for single spin azimuthal asymmetries due to the Collins effect in pion production from semi-inclusive deeply inelastic scattering off transversely and longitudinally polarized targets for the HERMES and COMPASS experiments. The x-dependence of the asymmetries is evaluated using the parton distribution functions from the chiral quark-soliton model. The overall normalization of the predicted asymmetries is determined by the information on the Collins fragmentation function extracted from previous HERMES data on azimuthal asymmetries AULsinfA_{\mathrm {{UL}}}^{\sin\phi} from a longitudinally polarized target. The single spin asymmetries A UT from the transversely polarized proton target are found to be about 20%20\% for positive and neutral pions both at HERMES and COMPASS. For a longitudinally polarized target we obtain for COMPASS AULsinf ~ 1%A_{\mathrm {{UL}}}^{\sin\phi}\sim 1\% and AULsin2f ~ 3%A_{\mathrm {{UL}}}^{\sin2\phi}\sim 3\% .
European Physical Journal C 12/2002; 32(3):337-346. DOI:10.1140/epjc/s2003-01398-6 · 5.08 Impact Factor