Quantum fluctuations in QCD influence nucleon structure and interactions, with pion production serving as a key probe of chiral dynamics. In this study, we present a lattice QCD calculation of multipole amplitudes at threshold, related to both pion electroproduction and weak production from a nucleon, using two gauge ensembles near the physical pion mass. We develop a technique for spin projection and construct multiple operators for analyzing the generalized eigenvalue problem in both the nucleon-pion system in the center-of-mass frame and the nucleon system with nonzero momentum. The numerical lattice results are then compared with those extracted from experimental data and predicted by low-energy theorems incorporating one-loop corrections.
@article{arxiv.2502.12074,
title = {Lattice QCD Study of Pion Electroproduction and Weak Production from a Nucleon},
author = {Yu-Sheng Gao and Zhao-Long Zhang and Xu Feng and Lu-Chang Jin and Chuan Liu and Ulf-G. Meißner},
journal= {arXiv preprint arXiv:2502.12074},
year = {2025}
}