Transverse single-spin asymmetries of pion production in semi-inclusive DIS at subleading twist

Abstract

We study the single-spin asymmetries with the sin φS and sin(2φ h − φS) angular dependences for charged and neutral pions produced in semi-inclusive deep inelastic scattering on the transversely polarized proton target. The theoretical interpretations of the two asymmetries are presented in terms of the convolution of the twist-3 quark transverse momentum dependent distributions and twist-2 fragmentation functions. Specifically, we investigate the role of the distributions fT , hT and h ⊥ T in the sin φS asymmetry, as well as the role of the distributions f ⊥ T , hT and h ⊥ T in the sin(2φ h −φS) asymmetry. We calculate these distributions in a spectator-diquark model and predict the corresponding asymmetries for the first time, considering the kinematics at HERMES, JLab and COMPASS. The numerical estimates show that the asymmetries are sizable, and the dominant contribution to the sin φS asymmetry comes from the T-odd distribution fT , while f ⊥ T gives the main contribution to the sin(2φ h − φS) asymmetry. The future measurements on these asymmetries can shed light on the information of twist-3 transverse momentum dependent distributions.

SIDIS Transverse Spin Asymmetries at COMPASS: Multy-Dimensional Analysis

“…This is the only DSA which appears to be non-zero at COMPASS and the last TSA for which a statistically significant signal has been detected. Remaining four asymmetries are found to be small or compatible with zero within available statistical accuracy which is in agreement with available predictions [19,20,28]. As an example the "3D:…”

Double spin asymmetriesALTcosϕSandAMao1, Lü2, Qiang3 et al. 2015Phys. Rev. DSelf Cite12290View full textAdd to dashboardCite

“…Sizable asymmetries have been observed and have provided the basis for several related theoretical studies [33][34][35][36][37][38][39]. Here we should mention a recent theoretical prediction [40] on the transverse SSAs at subleading twist. These asymmetries are of vital importance, as they provide complementary information on the spin and flavor structure of nucleon.…”

Semi-inclusive deep inelastic scattering in Wandzura-Wilczek-type approximation

“…More recently the A sin(2φ h −φ S ) U T was also studied in the model approach of Ref. [213]. Historically this was the earliest azimuthal SIDIS asymmetry to be discussed in literature: the first prediction for this asymmetry from intrinsic k ⊥ was made in [159,214], a first measurement was reported in [215].…”