Gluonic Excitations' Millennial Finale

TL;DR

This paper reviews recent theoretical advances in hybrid mesons and glueballs, discussing potential model issues, experimental candidates, decay mechanisms, and promising future experimental searches at B-factories and Jefferson Lab.

Contribution

It summarizes the latest developments in hybrid meson and glueball theory, highlighting new calculations, interpretations, and experimental prospects from the last year.

Findings

Cracks in potential models of conventional mesons.

Calculated hybrid meson adiabatic surfaces.

Experimental J^PC exotics may be hybrids, four-quark states, or non-resonant.

Abstract

We provide an overview of theoretical developments on hybrid mesons and glueballs in the last year at this turn of the millenium conference. Cracks in potential models of conventional mesons are developing. Hybrid meson adiabatic surfaces have been calculated and interpreted, experimental J^PC exotics have hybrid meson, four-quark state or non-resonant interpretations, and the strong decay mechanism of hybrids has been studied. All theoretical progress on hybrid mesons in the last year is mentioned. Overall features of glueballs are visited: decays and the successes of the large N_c limit. Two promising experimental areas are mentioned: charmonium hybrids at B-factories and s sbar hybrids at Jefferson Lab.