Journal article

Publication year: 2022

Journal: Physical Review D

Volume number: 105

Issue number: 9

ISSN: 2470-0010

eISSN: 2470-0029

Open access status: Hybrid

DOI Link: https://doi.org/10.1103/PhysRevD.105.094022

Publisher: American Physical Society

Abstract: 
We use a continuum quark + diquark approach to the nucleon bound-state problem in relativistic quantum field theory to deliver parameter-free predictions for the nucleon axial and induced pseudoscalar form factors, G(A) and G(P), and unify them with the pseudoscalar form factor G(5) or, equivalently, the pionnucleon form factor G(pi NN). We explain how partial conservation of the axial-vector current and the associated Goldberger-Treiman relation are satisfied once all necessary couplings of the external current to the building blocks of the nucleon are constructed consistently; in particular, we fully resolve the seagull couplings to the diquark-quark vertices associated with the axial-vector and pseudoscalar currents. Among the results we describe, the following are worth highlighting. A dipole form factor defined by an axial charge g(A) = G(A)(0) = 1.25(3) and a mass scale M-A = 1.23(3)m(N), where m(N) is the nucleon mass, can accurately describe the pointwise behavior of G(A). Concerning G(P), we obtain the pseudoscalar charge g(p)* = 8.80(23), and find that the pion pole dominance approach delivers a reliable estimate of the directly computed result. Our computed value of the pion-nucleon coupling constant, g(pi NN)/m(N) = 14.02(33)/GeV is consistent with recent precision determinations.

Harvard Citation style: Chen, C., Fischer, C., Roberts, C. and Segovia, J. (2022) Nucleon axial-vector and pseudoscalar form factors and PCAC relations, Physical Review D, 105(9), Article 094022. https://doi.org/10.1103/PhysRevD.105.094022

APA Citation style: Chen, C., Fischer, C., Roberts, C., & Segovia, J. (2022). Nucleon axial-vector and pseudoscalar form factors and PCAC relations. Physical Review D. 105(9), Article 094022. https://doi.org/10.1103/PhysRevD.105.094022