2003/12/25 by D. V. Bugg, D.V. Bugg, Bugg, D. V. +2
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #Nuclear physics research studies #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #hep-ph
paper · pdf · doi:10.48550/arxiv.hep-ph/0312346
15 pages, no figures. Accepted for publication in Euro. Phys. J C
arxiv created 2003/12/25 · openalex publication_date 2003/12/25 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The latest πN elastic scattering data are re-analysed to determine the coupling constant gc of the charged pion, using the dispersion relation for the invariant amplitude B(+). Depending on the choice of data-base, values g2c/4π= 13.80 to 13.65 are obtained with errors of ± 0.12. We re-examine the well known discrepancy with the Goldberger-Treiman relation. After allowing for the mass dependence of the pion decay constant fπ, a (2-3)% discrepancy is predicted, hence g2c/4π= 13.74 ± 0.10 in the prior case. The mass difference between charge states of Δ(1232) is M0 -M++ = 2.0 ± 0.4 MeV, close to twice the mass difference between neutron and proton. The difference in widths on resonance is Γ0 - Γ++ =3.8 ± 1.0 MeV. One may account for a width difference of 4.5 MeV from phase space for decays and the extra channel Δ0 → γn.