$\cos 2 \phi$ asymmetries in unpolarized semi-inclusive DIS

TL;DR

This paper calculates and predicts the $ ext{cos} 2 ext{phi}$ asymmetries in unpolarized SIDIS using Boer-Mulders and Collins functions, comparing with existing data and proposing future measurements to refine understanding of transverse momentum dependent distributions.

Contribution

It combines Boer-Mulders and Collins functions to predict $ ext{cos} 2 ext{phi}$ asymmetries in SIDIS across multiple experiments, providing new theoretical predictions and analysis.

Findings

Predicted larger asymmetries for $ ext{pi}^-$ compared to $ ext{pi}^+$ production.

Compared theoretical calculations with existing HERA and JLab data.

Provided predictions for upcoming HERMES and JLab experiments.

Abstract

We use the Boer-Mulders functions parameterized from unpolarized $p+D$ Drell-Yan data by the FNAL E866/NuSea Collaboration combined with recently extracted Collins functions to calculate the $\cos 2 \phi$ asymmetries in unpolarized semi-inclusive deeply inelastic scattering (SIDIS) processes both for ZEUS at Hadron Electron Ring Accelerator (HERA) and Jefferson Lab experiments (JLab), and to compare our results with their data. We also give predictions for the $\cos 2 \phi$ asymmetries of SIDIS in the kinematical regime of HERMES Collaboration, and the forthcoming JLab experiments. We predict that the $\cos 2 \phi$ asymmetries of semi-inclusive $\pi^-$ production are somewhat larger than that of $\pi^+$ production. We suggest to measure these two processes separately, which will provide more detail information on the Boer-Mulders functions as well as on the Collins functions.