Transverse Force on Quarks in DIS

TL;DR

This paper explores how transverse forces on quarks in deep inelastic scattering relate to nucleon spin structure, impact parameter distributions, and orbital angular momentum, revealing connections between GPDs and spin asymmetries.

Contribution

It introduces a framework linking transverse forces from spectator quarks to measurable spin asymmetries and orbital angular momentum changes in nucleons.

Findings

Transversely distorted impact parameter distributions lead to net transverse forces.

Transverse forces are related to twist-3 parton distribution functions.

The change in quark orbital angular momentum is connected to the difference between two OAM definitions.

Abstract

Generalized Parton Distributions (GPDs) provide information on the distribution of quarks in impact paarmeter space. For transversely polarized nucleons, these impact parameter distributions are transversely distorted and this deviation from axial symmetry leads on average to a net transverse force from the spectators on the active quark in a DIS experiment. %The strength of that force can be related to twist-3 PDFs. This force when acting along the whole trajectory of the active quark leads to a transverse single-spin asymmetries. For a longitudinally polarized nucleon target, the transverse force implies a torque acting on the quark Orbital Angular Momentum (OAM). The resulting change in OAM as the quark leaves the target equals the difference between the Jaffe-Manohar and Ji OAMs.