Sivers effect in semiinclusive deeply inelastic scattering

Abstract

The Sivers function is extracted from HERMES data on single spin asymmetries in semi-inclusive deeply inelastic scattering. Our analysis use a simple Gaussian model for the distribution of transverse parton momenta, together with the flavor dependence given by the leading 1/Nc approximation and a neglect of the Sivers antiquark distribution. We find that within the errors of the data these approximations are sufficient.

Exploring the structure of the proton through polarization observables inlp→jetX

“…As pointed out in [41,42], the ETQS matrix element is related to the transverse momentum dependent Sivers function [43]. (For experimental studies of the Sivers effect in semi-inclusive DIS we refer to [44,45], while extractions of the Sivers function from data were discussed in [46][47][48][49][50][51]). Thus, measuring A U T in l p → jet X would give a direct (complementary) handle on the Sivers effect.…”

Extracting Boer-Mulders functions fromp+DDrell-Yan processes

“…Another distribution having the same QCD origin of h ⊥ 1 is the Sivers function [16], which plays a important role in the single spin asymmetries (SSA) [17] measured in semi-inclusive deep inelastic scattering. Measurements of Sivers SSA at HERMES [18,19] and COMPASS [20,21] have been used in order to extract the Sivers functions by several groups [22,23,24,25,26]. All these fittings show that the Sivers functions for u and d quarks have similar size but opposite sign.…”

Fragmentation functions and parton distribution functions for the pion with the nonlocal interactions

“…The fragmentation function characterizes the probability for a hadron fragmented from a quark with the momentum fraction z. It plays a crucial role in analyzing the semi-inclusive processes in the electron-positron scattering, deep-inelastic proton-proton scattering, and so on [1][2][3][4][5][6][7][8][9][10][11]. The parton distribution function provides information for the distribution of the momentum fraction x carried by a parton inside a hadron.…”