Semi-inclusive π0 target and beam-target asymmetries from 6 GeV electron scattering with CLAS

We present precision measurements of the target and beam-target spin asymmetries from neutral pion electroproduction in deep-inelastic scattering (DIS) using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. We scattered 6-GeV, longitudinally polarized electrons off longitudinally polarized protons in a cryogenic 14NH3 target, and extracted double and single target spin asymmetries for ep→e′π0X in multidimensional bins in four-momentum transfer (1.0<Q2<3.2 GeV2), Bjorken-x (0.12<x<0.48), hadron energy fraction (0.4<z<0.7), transverse pion momentum (0<PT<1.0 GeV), and azimuthal angle ϕh between the lepton scattering and hadron production planes. We extracted asymmetries as a function of both x and PT, which provide access to transverse-momentum distributions of longitudinally polarized quarks. The double spin asymmetries depend weakly on PT. The sin⁡2ϕh moments are zero within uncertainties, which is consistent with the expected suppression of the Collins fragmentation function. The observed sin⁡ϕh moments suggest that quark gluon correlations are significant at large x. Keywords: Semi-inclusive deep-inelastic scattering, Single spin asymmetries, Double spin asymmetries, Transverse momentum distributions, Collins fragmentation

Abstract licence: CC BY

A person counts once a day per paper. We keep no cookie and no address: a reader is a hash that changes every day. Any month under five reads shows no number.