We report on our calculation of the nucleon axial charge gA in QCD with two flavours of dynamical quarks. A detailed investigation of systematic errors is performed, with a particular focus on contributions from excited states to three-point correlation functions. The use of summed operator insertions allows for a much better control over such contamination. After performing a chiral extrapolation to the physical pion mass, we find gA=1.223 +/- 0.063 (stat) +0.035 -0.060 (syst), in good agreement with the experimental value.
@article{arxiv.1205.0180,
title = {The nucleon axial charge from lattice QCD with controlled errors},
author = {S. Capitani and M. Della Morte and G. von Hippel and B. Jäger and A. Jüttner and B. Knippschild and H. B. Meyer and H. Wittig},
journal= {arXiv preprint arXiv:1205.0180},
year = {2013}
}
Comments
6 pages, 5 figures, table and figure added, results and conclusions unchanged; version to appear in Physical Review D