Quarkonium: New Developments
Abstract
Description
To illustrate the campaign to understand heavy quarkonium systems, I focus on a puzzling new state, $X(3872) \to π^+π^- J/ψ$. Studying the influence of open-charm channels on charmonium properties leads us to propose a new charmonium spectroscopy: additional discrete charmonium levels that can be discovered as narrow resonances of charmed and anticharmed mesons. I recall some expectations for a new spectroscopy of mesons with beauty and charm, the $B_c$ ($b\bar{c}$) system. Throughout, I call attention to open issues for theory and experiment.
20 pages, 13 figures, uses boxedeps and LaThuileFPSproa.sty (included). Presented at XVIII Rencontres de la Vallee d'Aoste, La Thuile 2004. One added reference, one typo fixed
20 pages, 13 figures, uses boxedeps and LaThuileFPSproa.sty (included). Presented at XVIII Rencontres de la Vallee d'Aoste, La Thuile 2004. One added reference, one typo fixed