English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

The nucleon-pion-state contribution to QCD two- and three-point functionsused in the calculation of the axial form factors of the nucleon are studied inchiral perturbation theory. For physically small quark masses the nucleon-pionstates are expected to dominante the excited-state contamination at largeeuclidean time separations. To leading order in chiral perturbation theory theresults depend on two experimentally well-known low-energy constants only andthe nucleon-pion-state contribution can be reliably estimated. Thenucleon-pion-state contribution to the axial form factor $G_{\rm A}(Q^2)$ is atthe 5 percent level for source-sink separations of 2 fm and shows almost nodependence on the momentum transfer $Q^2$. In contrast, for the induced pseudoscalar form factor $G_{\rm P}(Q^2)$ the nucleon-pion-state contribution shows arather strong dependence on $Q^2$ and leads to a 10 to 40 percentunderestimation of $G_{\rm P}(Q^2)$ at small momentum transfers. Applying theChPT results to recent lattice data generated by the PACS collaboration we findagreement with experimental data and the predictions of the pion-pole dominancemodel.

Nucleon-pion-state contamination in lattice calculations of the axial form factors of the nucleon