Lattice QCD Study of Pion Electroproduction and Weak Production from a Nucleon

<p>Quantum fluctuations in QCD influence nucleon structure and interactions, with pion production serving as a key probe of chiral dynamics. In this Letter, 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.</p> <sec> <title/> <supplementary-material> <permissions> <copyright-statement>Published by the American Physical Society</copyright-statement> <copyright-year>2025</copyright-year> </permissions> </supplementary-material> </sec>. Authors: Gao, Yu-Sheng (ORCID:0009000406829247); Zhang, Zhao-Long; Feng, Xu (ORCID:0000000208560649); Jin, Lu-Chang (ORCID:0000000308064183); Liu, Chuan (ORCID:0000000344976868). DOE Contract: SC0010339; SC0021147