Nucleon Structure from Lattice QCD

TL;DR

This paper presents lattice QCD calculations of nucleon structure, including form factors and sea-quark contributions, using stochastic estimation techniques on a quenched lattice to explore fundamental properties of nucleons.

Contribution

It introduces a detailed lattice QCD study of nucleon form factors and sea-quark effects, employing stochastic noise methods and extrapolations to the chiral limit, providing new insights into nucleon structure.

Findings

Determined nucleon axial, electromagnetic, and scalar form factors.

Calculated strange quark condensate and $ N $ sigma term.

Validated the use of $Z_2$ noise as optimal for stochastic estimation.

Abstract

We report results on the nucleon structure obtained from the lattice quantum chromodynamics calculation. These include the axial, electromagnetic, $\pi NN$, and scalar form factors. The calculation is carried out at $\beta = 6$ on a $16^3 \times 24$ lattice with 24 quenched gauge configurations. The chiral limit results are extrapolated from several light quark cases. For the disconnected insertion (sea-quark contribution), we used the stochastic estimation with the $Z_2$ noise to calculate the diagonal and off-diagonal traces of the inverse matrices with a size of $10^6 \times 10^6$. It is found that the $Z_2$ noise is the optimal choice and its comparison with the Gaussian noise for our quark matrix is given. For the sea-quark contribution, we report results on the strange condensate in the nucleon and the $\pi N \sigma$ term.