Tests for Sivers, Boer-Mulders and transversity distributions in difference cross sections in SIDIS

TL;DR

This paper proposes a method to analyze azimuthal asymmetries in SIDIS to extract Sivers, Boer-Mulders, and transversity distributions, simplifying the process especially on deuteron targets and under certain data conditions.

Contribution

It introduces simplified expressions for asymmetries in SIDIS that enable direct tests of assumptions used in extracting transverse momentum dependent distributions.

Findings

Asymmetries on deuteron targets depend only on valence-quark distributions.

Simplified formulas allow for straightforward tests of distribution extraction assumptions.

Current data can be used for these tests if Q^2-dependence is negligible.

Abstract

A major experimental program is presently underway to determine the Sivers, Boer-Mulders and transversity distributions, vital for understanding the internal structure of the nucleon. To this end we consider the Sivers, Boer-Mulders and transversity azimuthal asymmetries of the difference cross sections of hadrons with opposite charges in SIDIS reactions with unpolarized and transversely polarized target l+N\to l'+h+X, h=\pi^\pm, K^\pm, h^\pm. We show that on deuteron target these asymmetries are particularly simple and determine the sum of the valence-quark Q_V=u_V+d_V transverse momentum dependent distributions without any contributions from the strange or other sea-quark functions. At present, data on these asymmetries are presented for the integrated asymmetries i.e. the x_B- and z_h-dependent asymmetries. If data are available in small bins in Q^2, so that Q^2-dependence can be neglected, these expressions simplify dramatically leading to remarkably simple and powerful tests of the simplifying assumptions used in extracting these functions from the data.