2024/05/14 by Yohei Ema, Ting Gao, Ema, Yohei +5 · 2 citations
Physics and Astronomy · #Atomic and Subatomic Physics Research #FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #High Energy Physics - Phenomenology (hep-ph) #Nuclear Theory (nucl-th) #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions
paper · pdf · doi:10.48550/arxiv.2405.08856
openalex publication_date 2024/05/14 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
We revisit the chiral properties of nucleon interpolating currents, and show that of the two leading order currents j1 and j2, only two linear combinations j1± j2 transform covariantly under the anomalous U(1)A symmetry. As a result, calculations of quantities which vanish by symmetry in the chiral limit may produce unphysical results if carried out with different linear combinations of the currents. This includes observables such as electric dipole moments, induced by the QCD parameter θ, and the θ-dependence of the nucleon mass. For completeness, we also exhibit the leading order results for nucleon electric dipole moments (dn,p) induced by θ, and the nucleon magnetic moments (μn,p), when calculated using QCD sum rules for both the covariant choices of the nucleon interpolating current. The results in each channel, conveniently expressed as the ratios, dn,p/μn,p, are numerically consistent, and reflect the required physical dependence on θ.