AN ELEMENTARY PARTICLE CONSTITUENT-QUARK MODEL

A comparison of meson masses with baryon excitation energies reveals a common mass-band structure, in which particles with a variety of quantum numbers are grouped together. These quantized mass values seemingly mandate a constituent-quark (CQ) viewpoint. By studying the meson and baryon yrast states, we can deduce the masses and spin values of some of the constituent quarks. A comprehensive CQ model is presented that reproduces the observed spectrum of hadrons and leptons. These CQ quarks include the standard u, d, s, c, b set of quarks as a subset. The quark generation process, which features characteristic mass triplings, is a key ingredient of this CQ model. All of the constituent-quark masses are formed from a set of three basic masses, two spinning and one spinless, which are directly related to the masses of the electron, muon, and pion. The mass quantum X=420 MeV is a dominant excitation state that dictates meson, baryon, and lepton mass values. The quantum X occurs in both S=0 and S=1 spin configurations, and it serves as a «window» for transformations between orbital and spin angular momenta. The fully relativistic spinning sphere, with its distinctive 3/2 mass increase, provides an isoergic link between spinless and spinning excitation quanta. The fine-structure constant α and the charge-splitting quantum ε=9 m e provide links between quarks and leptons. Particle lifetimes and decay modes reflect constituent-quark substructures. © 1990 Società Italiana di Fisica.