The Constituent Quark Model has provided a remarkable description of the experimentally observed ha&on spectrum but still has no firm theoretical basis. Attempts to provide a QCD justification discussed at Hadron99 include QCD Sum Rules, instantons, relativistic potential models and the lattice. Phenomenological analyses to clarify outstanding problems like the nature of the scalar and pseudoscalar mesons and the tow branching ratio for ยข' --~ p -7r were presented. New experimental puzzles include the observation of/3p --+ ยข7r.
1. Introduction
Is there a theory? QCD is supposed to explain everything about Hadron Spectroscopy -But How? QED is supposed to explain everything about Superconductivity -But How? Will explaining Hadron Spectroscopy from first principles using QCD be as difficult as explaining Superconductivity from first principles using QED?
1.1. The Sakharov-Zeldovich 1966 quark model (SZ66)
Andrei Sakharov, a pioneer in quark-hadron physics asked in 1966 "Why are the A and E masses different? They are made of the same quarks". Sakharov and Zeldovich . assumed a quark model for hadrons with a flavor dependent linear mass term and hyperfine