Journalartikel

Jahr der Veröffentlichung: 2023

Zeitschrift: The European Physical Journal A

Bandnummer: 59

Heftnummer: 7

ISSN: 1434-6001

eISSN: 1434-601X

DOI Link: https://doi.org/10.1140/epja/s10050-023-01066-9

Verlag: Springer

Abstract: 
A quark + diquark Faddeev equation treatment of the baryon bound state problem in Poincare-invariant quan-tum field theory is used to deliver parameter-free predictions for all six Delta-baryon elastic weak form factors. Amongst the results, it is worth highlighting that there are two dis-tinct classes of such Delta-baryon form factors, (g(1) , g(3) , G(pi Delta Delta)), (h(1) , h(3) , H-pi Delta Delta), the functions within each of which are sepa-rately linked via partial conservation of axial current (PCAC) and Goldberger-Treiman (GT) relations. Respectively with in each class, the listed form factors possess qualitatively the same structural features as the nucleon axial, induced pseudoscalar, and pion-nucleon coupling form factors. For instance, the Delta-baryon g1 axial form factor can reliably be approximated by a dipole function, characterised by an axial charge g(Delta+) (A) = 0.71(9) and mass-scale m(A)(Delta) = 0.95(2)m(Delta). Moreover, the two distinct Delta-baryon PCAC form factor rela-tions are satisfied to a high degree of accuracy on a large range of Q(2); the associated GT relations present good approxima-tions only on Q(2)/ m(Delta)(2) similar or equal to 0; and pion pole dominance approx-imations are reliable within both classes. There are two pi Delta Delta couplings: g(pi Delta Delta) = 10.46(1.88); h(pi Delta Delta) = 35.73(3.75); and the associated form factors are soft. Such couplings com-monly arise in phenomenology, which may therefore bene-fit from our analyses. A flavour decomposition of the axial charges reveals that quarks carry 71% of the Delta-baryon spin. The analogous result for the proton is approximate to 65%.

Harvard-Zitierstil: Yin, P., Chen, C., Fischer, C. and Roberts, C. (2023) Δ-Baryon axialvector and pseudoscalar form factors, and associated PCAC relations, The European Physical Journal A, 59(7), Article 163. https://doi.org/10.1140/epja/s10050-023-01066-9

APA-Zitierstil: Yin, P., Chen, C., Fischer, C., & Roberts, C. (2023). Δ-Baryon axialvector and pseudoscalar form factors, and associated PCAC relations. The European Physical Journal A. 59(7), Article 163. https://doi.org/10.1140/epja/s10050-023-01066-9