We have measured the moment Asin ϕ LU corresponding to the polarized electron beam-spin asymmetry in semi-inclusive deep inelastic scattering. Asin ϕ LU is a twist-3 quantity providing information about quarkgluon correlations. Data were taken with the CLAS Spectrometer at Jefferson Lab using a 5.498 GeV longitudinally polarized electron beam and an unpolarized liquid hydrogen target. All three pion channels (πþ, π0 and π−) were measured simultaneously over a large range of kinematics within the virtuality range Q2 ≈ 1.0–4.5 GeV2. The observable was measured with better than 1% statistical precision over a large range of z, PT, xB, and Q2, which permits comparison with several reaction models. The discussed measurements provide an upgrade in statistics over previous measurements, and serve as the first evidence for the negative sign of the π− sin ϕ moment
Beam-spin asymmetries from semi-inclusive pion electroproduction
CONTALBRIGO, Marco;LENISA, Paolo;PAPPALARDO, Luciano Libero;
2014
Abstract
We have measured the moment Asin ϕ LU corresponding to the polarized electron beam-spin asymmetry in semi-inclusive deep inelastic scattering. Asin ϕ LU is a twist-3 quantity providing information about quarkgluon correlations. Data were taken with the CLAS Spectrometer at Jefferson Lab using a 5.498 GeV longitudinally polarized electron beam and an unpolarized liquid hydrogen target. All three pion channels (πþ, π0 and π−) were measured simultaneously over a large range of kinematics within the virtuality range Q2 ≈ 1.0–4.5 GeV2. The observable was measured with better than 1% statistical precision over a large range of z, PT, xB, and Q2, which permits comparison with several reaction models. The discussed measurements provide an upgrade in statistics over previous measurements, and serve as the first evidence for the negative sign of the π− sin ϕ momentI documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.