Progress and Issues in Hadronic Theory

Abstract

A brief review of progress and issues in hadronic theory and phenomenology is presented. New results for the $X(3872)$, $Z_c(3900)$, and $Z_c(4020)$ are discussed and unresolved issues are highlighted. A series of open problems in pQCD, NRQCD, and general phenomenology is given. It is argued that these indicate that the current understanding of hadronic dynamics is poor. In particular old ideas about quark annihilation and factorisation appear to be incorrect, pQCD looks limited in scope, and the convergence of some NRQCD computations appears jeapardised by the relative lightness of the charm quark mass.