Simple symmetry breaking in a chiral SU(4) × SU(4) model of pseudoscalar mesons

Abstract

We calculate the effects of simple symmetry breaking on the mass spectrum, neutral isoscalar mixing angles, and decays of pseudoscalar mesons using a chiral SU(4) nonlinear model to describe the mesons. We find that in addition to quark-mass-type terms, a simple U(1)-breaking term will induce a reasonable isoscalar mass spectrum, give a low value for the ${\eta }^{\prime }\to \eta \pi \pi$ decay, and is the dominant contribution to the ${\eta }^{\prime \prime }$ (paracharmonium) decay into three isoscalars. We also calculate the effects of symmetry breaking on hadronic currents and thus on the weak decays of new mesons.