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arXiv · 2003.10158

On the axial-vector form factor of the nucleon and chiral symmetry

Matthias F. M. Lutz·Ulrich Sauerwein·Rob G. E. Timmermans
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Abstract

We consider the chiral Lagrangian with nucleon, isobar, and pion degrees of freedom. The baryon masses and the axial-vector form factor of the nucleon are derived at the one-loop level. We explore the impact of using on-shell baryon masses in the loop expressions. As compared to results from conventional chiral perturbation theory we find significant differences. An application to QCD lattice data is presented. We perform a global fit to the available lattice data sets for the baryon masses and the nucleon axial-vector form factor, and determine the low-energy constants relevant at N$^3$LO for the baryon masses and at N$^2$LO for the form factor. Partial finite-volume effects are considered. We point out that the use of on-shell masses in the loops results in non-analytic behavior of the baryon masses and the form factor as function of the pion mass, which becomes prominent for larger lattice volumes than presently used.

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Matthias F. M. Lutz, Ulrich Sauerwein, Rob G. E. Timmermans. 2020-03-23. On the axial-vector form factor of the nucleon and chiral symmetry. https://doi.org/10.1140/epjc%2Fs10052-020-8417-5

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