Current Problems In Light Meson Spectroscopy

I describe the status of lattice studies of mesons composed of light (u/d/s) quarks and of gluons, and describe the challenges and prospects for future calculations. I focus in particular on delineating single- and multiparticle states in the spectrum, and of discerning the properties of resonances.

Recent discoveries of a number of unexpected new charmomium-like meson states at the BaBar and Belle B-factories have demonstrated how little is still known about meson spectroscopy. In this talk we will review recent highlights of the light quark spectroscopy from collider and fixed target experiments.

The second course of the International School on Physics with Low Energy Antiprotons was held in Erice, Sicily at the Ettore Majorana Centre for Scientific Culture, from May 20 to May 31, 1987. The School is dedicated to physics accessible to experiments using low energy antiprotons, especially in view of operation of the LEAR facility at CERN with the upgraded antiproton source AAC (Antiproton Accumulator AA and Antiproton Collector ACOL). The first course in 1986 covered topics related to fundamental symmetries. This book contains the proceedings of the second course which focused on spectroscopy of light and heavy quarks. These proceedings contain both the tutorial lectures and contri butions presented by participants during the School. The papers are organized in four sections: The first section includes theoretical reviews. Section II contains experimental reviews and covers the results in meson spectroscopy from DM2, MARK III, GAMS and n-WA76. Section III presents the new meson spectroscopy experiments in pre paration at CERN and Fermilab: Crystal Barrel, OBELIX, Jetset and E760. Section IV is dedicated to LEAR and to future facilities where meson spectroscopy would be a principal component of the physics programme. We should like to thank Dr. Alberto Gabriele and the staff of the Ettore Majorana Centre who provided for a smooth running of the School and a very pleasant stay. We are particularly grateful to Mrs. Anne Marie Bugge for her crucial help during the preparation and running of the School and for the editing of these Proceedings.

A comparative survey of established meson states with the predictions of a q anti q (quarkonium) model by Godfrey and Isgur shows that most meson states are well described, from pion to UPSILON(6S). However, a number of states in the light- quark isoscalar sector are not predicted at all in their model, pointing to a need for glueballs, hybrids and multi-quark states to fully account for recently reported meson states. 48 refs.