Quartet Scheme of Hadrons in Chiral $U(4) \otimes U(4)$

Abstract

A general scheme of fundamental quartets is reformulated on the basis of strict lepton-baryon symmetry, and treated in a context of chiral U(4) ⊗U(4) invariance. The structure of spontaneous breaking of it accompanied by sixteen Nambu-Goldstone bosons is studied in detail. One of the main predictions of our model is the existence of a new 0--meson, χ, with the mass heavier by ∼0.5 GeV than the charmed partners, which may be identified with new heavy particles recently reported by Niu et al. It decays predominantly as χ→K + K + (π,ηor η′) with small decay widths (∼a few MeV). Such an indication of the existence of new heavy particles is encouraging enough to push forward our new treatment of the fundamental quartets (quartons) as a natural generalization of the Sakata-Nagoya model.