Proton and neutron electromagnetic radii and magnetic moments from \(N_f = 2 + 1\) lattice QCD

We present results for the electromagnetic form factors of the proton and neutron computed on the \((2 + 1)\)-flavor Coordinated Lattice Simulations (CLS) ensembles including both quark-connected and -disconnected contributions. The \(Q^2\)-, pion-mass, lattice-spacing, and finite-volume dependence...

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Bibliographic Details
Published in:arXiv.org 2023-12
Main Authors: Salg, Miguel, Djukanovic, Dalibor, Georg von Hippel, Meyer, Harvey B, Ottnad, Konstantin, Wittig, Hartmut
Format: Article
Language:English
Subjects:
Chiral dynamics
Flavor (particle physics)
Form factors
Magnetic moments
Momentum transfer
Perturbation theory
Pions
Protons
Quantum chromodynamics
Vector mesons
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Summary:We present results for the electromagnetic form factors of the proton and neutron computed on the \((2 + 1)\)-flavor Coordinated Lattice Simulations (CLS) ensembles including both quark-connected and -disconnected contributions. The \(Q^2\)-, pion-mass, lattice-spacing, and finite-volume dependence of our form factor data is fitted simultaneously to the expressions resulting from covariant chiral perturbation theory including vector mesons amended by models for lattice artefacts. From these fits, we determine the electric and magnetic radii and the magnetic moments of the proton and neutron, as well as the Zemach radius of the proton. To assess the influence of systematic effects, we average over various cuts in the pion mass and the momentum transfer, as well as over different models for the lattice-spacing and finite-volume dependence, using weights derived from the Akaike Information Criterion (AIC). Our results for the magnetic moments of the proton and neutron are in good agreement with the experimental values and have a relative precision of about \(2.4\,\%\) and \(3.7\,\%\), respectively. For the electromagnetic radii of the proton, we achieve a precision at the \(1.5\,\%\) level.
ISSN:2331-8422
DOI:10.48550/arxiv.2401.05404