Theoretical Summary of the HADRON99 conference

Abstract

The Constituent Quark Model has provided a remarkable description of the experimentally observed hadron 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 low branching ratio for $ψ' \to ρ-π$ were presented. New experimental puzzles include the observation of $\bar p p \to ϕπ$.