Measurement of “Pretzelosity” Asymmetry of Charged Pion Production in Semi-Inclusive Deep Inelastic Scattering on a Polarized 3 He Target

An experiment to measure single-spin asymmetries of semi-inclusive production of charged pions in deepinelastic scattering on a transversely polarized 3He target was performed at Jefferson Laboratory in the kinematic region of 0.16 asymmetries on 3He, which are expressed as the convolution of the h⊥ 1T transverse-momentum-dependent distribution functions and the Collins fragmentation functions in the leading order, were measured for the first time. Under the effective polarization approximation, we extracted the corresponding neutron asymmetries from the measured 3He asymmetries and cross-section ratios between the proton and 3He. Our results show that both π± on 3He and on neutron pretzelosity asymmetries are consistent with zero within experimental uncertainties.