Octet baryon magnetic moments at next-to-next-to-leading order in covariant chiral perturbation theory

• Published in: The European physical journal. C, Particles and fields Particles and fields, 2018-06, Vol.78 (6), p.1-12, Article 489
• Main Authors: Xiao, Yang, Ren, Xiu-Lei, Lu, Jun-Xu, Geng, Li-Sheng, Meißner, Ulf-G.
• Format: Article
• Language: English
• Subjects: Astronomy; Astrophysics and Cosmology; Baryons; Chiral dynamics; Convergence; Dependence; Elementary Particles; Formulations; Hadrons; Heavy Ions; Magnetic moments; Magnetism; Measurement Science and Instrumentation; Nuclear Energy; Nuclear Physics; Perturbation methods; Perturbation theory; Physics; Physics and Astronomy; Quantum chromodynamics; Quantum Field Theories; Quantum Field Theory; Regular Article - Theoretical Physics; String Theory
• ISSN: 1434-6044; 1434-6052
• DOI: 10.1140/epjc/s10052-018-5960-4

We calculate the octet baryon magnetic moments in covariant baryon chiral perturbation theory with the extended-on-mass-shell renormalization scheme up to next-to-next-to-leading order. At this order, there are nine low-energy constants, which cannot be uniquely determined by the seven experimental data alone. We propose two strategies to circumvent this problem. First, we assume that chiral perturbation theory has a certain convergence rate and use this as one additional constraint to fix the low-energy constants by fitting to the experimental data. Second, we fit to lattice QCD simulations to determine the low-energy constants. We then compare the resulting predictions of the light and strange quark mass dependence of the octet baryon magnetic moments by the three mostly studied formulations of baryon chiral perturbation theory, namely, the extended-on-mass-shell, the infrared, and the heavy baryon approaches. It is shown that once more precise lattice data become available, one will learn more about the convergence pattern of baryon chiral perturbation theory.