UA(1) symmetry breaking, scalar mesons and the nucleon spin problem in an effective chiral field theory Original Research Article

We establish a relationship between the scalar-meson spectrum and the View the MathML source symmetry-breaking ʹt Hooft interaction on one hand and the constituent-quark flavor singlet axial coupling constant View the MathML source on the other, using an effective chiral quark field theory. This analysis leads to the new sum rule View the MathML source, where η′,η,K are the observed pseudoscalar mesons, View the MathML source is the strange scalar meson at 1430 MeV and View the MathML source are “the eighth and the ninth” scalar mesons. We discuss the relationship between the constituent-quark flavor singlet axial coupling constant View the MathML source and the nucleon one View the MathML source (“nucleon spin content”) in this effective field theory. We also relate View the MathML source as well as the flavour octet constituent-quark axial coupling constant View the MathML source to vector and axial-vector meson masses in general as well as in the tight-binding limit.