Sign Reversal of Boer-Mulders Functions from Semi-inclusive Deep-Inelastic Scattering to the Drell-Yan Process

TL;DR

This paper reviews the theoretical prediction and experimental evidence for the sign reversal of Boer-Mulders functions between SIDIS and Drell-Yan processes, confirming current data consistency and discussing future tests at EIC.

Contribution

It provides a comprehensive analysis of the sign reversal prediction for Boer-Mulders functions and evaluates current experimental data supporting this QCD prediction.

Findings

Current SIDIS and Drell-Yan data are consistent with the predicted sign reversal.

The sign reversal applies to the proton's valence quark Boer-Mulders functions.

Future EIC experiments could test the sign reversal for pion Boer-Mulders functions.

Abstract

A striking prediction of QCD on the properties of the novel Transverse Momentum Dependent (TMD) distribution functions is that the time-reversal odd Sivers and Boer-Mulders functions extracted from semi-inclusive deep-inelastic scattering (SIDIS) will undergo a sign reversal in the Drell-Yan (DY) process. This prediction has been tested by experiments that have focused on the Sivers functions so far. We examine the current status on the theoretical prediction and experimental extraction of the signs of the Boer-Mulders functions from SIDIS and DY. We show that the existing SIDIS and DY data are consistent with the predicted sign reversal of the Boer-Mulders functions for proton's valence quark distribution. Prospects for future experiments at EIC capable of testing the sign reversal of the pion Boer-Mulders functions are also discussed.