Spin-orbit correlation and spatial distributions for spin-0 hadrons

TL;DR

This paper explores the spin-orbit correlation in spin-0 hadrons using form factors, revealing a relationship with chiral stress and providing spatial distributions based on existing electromagnetic form factor data.

Contribution

It introduces a novel connection between spin-orbit correlation and chiral stress in spin-0 hadrons, and presents spatial distributions derived from current form factor parametrizations.

Findings

Spin-orbit correlation equals minus half the valence quark number when neglecting quark mass.

The form factor $ ilde F^q(t)$ relates to a torque interpreted as chiral stress.

Spatial distributions for pions, kaons, and alpha particles are provided.

Abstract

The spin-orbit correlation in spin-0 hadrons can be investigated through the kinetic energy-momentum tensor form factor $\tilde F^q(t)$. We observe that the latter is also related to a torque about the radial direction, which we interpret as a chiral stress. If we neglect the quark mass contribution, then $\tilde F^q(t)$ is simply proportional to the electromagnetic form factor for spin-0 hadrons, and the spin-orbit correlation is equal to minus half of the valence quark number. Given the extensive studies on the electromagnetic form factor for spin-0 hadrons such as pions, kaons, and the $\alpha$ particle, we present the spatial distributions of chiral stress and kinetic spin-orbit correlation based on current parametrizations of the pion electromagnetic form factor.