Abstract
We present an analysis of the pion-nucleon -term using six ensembles with -flavor highly improved staggered quark action generated by the MILC Collaboration. The most serious systematic effect in lattice calculations of nucleon correlation functions is the contribution of excited states. We estimate these using chiral perturbation theory () and show that the leading contribution to the isoscalar scalar charge comes from and states. Therefore, we carry out two analyses of lattice data to remove excited-state contamination, the standard one and a new one including and states. We find that the standard analysis gives , consistent with previous lattice calculations, while our preferred -motivated analysis gives , which is consistent with phenomenological values obtained using scattering data. Our data on one physical pion mass ensemble were crucial for exposing this difference, therefore, calculations on additional physical mass ensembles are needed to confirm our result and resolve the tension between lattice QCD and phenomenology.
- Received 9 September 2021
- Revised 18 October 2021
- Accepted 27 October 2021
DOI:https://doi.org/10.1103/PhysRevLett.127.242002
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.
Published by the American Physical Society