Angular momentum content of the rho-meson in lattice QCD

TL;DR

This paper uses lattice QCD to analyze the rho-meson's angular momentum content, revealing a simple 3S1-wave composition consistent with quark model predictions.

Contribution

It introduces a gauge-invariant method to determine the partial wave content of mesons in the infrared using the variational approach and chiral to LSJ basis transformation.

Findings

The rho-meson has a dominant 3S1-wave component in the infrared.

Results are consistent across quenched and dynamical quark simulations.

The method provides a new way to study meson internal structure in lattice QCD.

Abstract

The variational method allows one to study the mixing of interpolators with different chiral transformation properties in the non-perturbatively determined physical state. It is then possible to define and calculate in a gauge-invariant manner the chiral as well as the partial wave content of the quark-antiquark component of a meson in the infrared, where mass is generated. Using a unitary transformation from the chiral basis to the LSJ basis one may extract a partial wave content of a meson. We present results for the ground state of the rho-meson using quenched simulations as well as simulations with two dynamical quarks, all for lattice spacings close to 0.15 fm. We point out that these results indicate a simple 3S1-wave composition of the rho-meson in the infrared, like in the SU(6) flavor-spin quark model.