The $\sin(2\phi)$ azimuthal asymmetry in exclusive $\pi^0$ production

TL;DR

This paper predicts the $ ext{sin}(2 ext{phi})$ azimuthal asymmetry in exclusive $ ext{pi}^0$ production at future colliders, linking it to quark orbital angular momentum using a light-front quark model based on AdS/QCD.

Contribution

It introduces a theoretical calculation of the azimuthal asymmetry in exclusive $ ext{pi}^0$ production using a novel light-front quark-scalar-diquark model derived from AdS/QCD, providing constraints before experimental measurement.

Findings

Predicted asymmetry values for EIC and EicC kinematics.

Linked asymmetry to quark orbital angular momentum.

Provided theoretical constraints for future experiments.

Abstract

The $\sin(2\phi)$ azimuthal angular correlation between the transverse momenta of the scattered electron and the recoil proton in the $ep\to e^\prime p^\prime \pi^0$ process provides a probe for quark orbital angular momentum. We numerically calculate this asymmetry for the future Electron-Ion Collider (EIC) in the U.S. and China (EicC) kinematics using a light-front quark-scalar-diquark model, in which the light-front wave functions (LFWFs) are derived from the soft-wall AdS/QCD framework. We also investigate the properties of the valence quark angular momentum expressed in terms of helicity-independent and helicity-dependent parton distributions. This study aims to establish theoretical constraints on the asymmetry sensitive to the quark orbital angular momentum prior to its first experimental measurement.