$N\pi$-state contamination in lattice calculations of the nucleon pseudoscalar form factor
Abstract
The nucleon-pion-state contribution in the QCD 3-point function of the pseudoscalar density is calculated to leading order in chiral perturbation theory. It predicts a nucleon-pion-state contamination in lattice estimates for the pseudoscalar form factor determined with the plateau method. Depending on the momentum transfer the contamination varies between -20% and +50% for a source-sink separation of 2 fm. The nucleon-pion-state contamination also causes violations in the generalized Goldberger-Treiman relation among the pseudoscalar and the axial nucleon form factors, the dominant source being the nucleon-pion-state contamination in the induced pseudoscalar form factor . Comparing the chiral perturbation theory predictions with lattice results of the PACS collaboration we find reasonable agreement even for source-sink separations as small as 1.3 fm.
Keywords
Cite
@article{arxiv.1906.03652,
title = {$N\pi$-state contamination in lattice calculations of the nucleon pseudoscalar form factor},
author = {Oliver Bar},
journal= {arXiv preprint arXiv:1906.03652},
year = {2019}
}
Comments
22 pages, 9 figures. Revised version: Minor changes in section III and IV, typos corrected, references added, results and conclusions unchanged. Matches version published in Phys. Rev. D. arXiv admin note: text overlap with arXiv:1812.09191