A Lattice Study of the Magnetic Moment and the Spin Structure of the Nucleon

TL;DR

This study calculates the nucleon magnetic moment and spin structure using lattice QCD without momentum extrapolation, providing new insights into quark contributions with different lattice masses.

Contribution

It introduces a momentum-extrapolation-free method for calculating nucleon properties in lattice QCD and compares results with previous approaches.

Findings

Consistent nucleon magnetic moments across different quark masses.

Quantified quark angular momentum contributions to nucleon spin.

Analyzed disconnected diagrams at the largest quark mass.

Abstract

Using an approach free from momentum extrapolation, we calculate the nucleon magnetic moment and the fraction of the nucleon spin carried by the quark angular momentum in the quenched lattice QCD approximation. Quarks with three values of lattice masses, 210, 124 and 80 MeV, are formulated on the lattice using the standard Wilson approach. At every mass, 100 gluon configurations on 16^3 x 32 lattice with \beta=6.0 are used for statistical averaging. The results are compared with the previous calculations with momentum extrapolation. The contribution of the disconnected diagrams is studied at the largest quark mass using noise theory technique.