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a r X i v : h e p - p h / 0 6 0 9 2 4 0 v 1 2 2 S e p 2 0 0 6 February 2, 2008 7:15 WSPC - Proceedings Trim Size: 9in x 6in colangelo˙qcd06 1 NEW OPEN AND HIDDEN CHARM SPECTROSCOPY P. COLANGELO?, F. DE FAZIO, R. FERRANDES, S. NICOTRI Istituto Nazionale di Fisica Nucleare, Sezione di Bari, Bari, Italy ?E-mail: pietro.colangelo@ba.infn.it Many new results on open and hidden charm spectroscopy have been obtained recently. We present a short review of the experimental findings in the meson sector, of the theoretical interpretations and of the open problems, with a discussion on the possibility that some mesons are not quark-antiquark states. Keywords: charmed mesons, quarkonium, nonstandard quark/gluon states 1. Introduction Observation of a long list of new hadrons has been recently reported by experiments at e+e? and pp? colliders, by fixed target experiments and by reanalyses of old data. We can use Leporello’s words in Mozart’s Don Gio- vanni: Madamina, il catalogo e? questo: a D?sJ (2317), DsJ (2460), DsJ(2632), DsJ(2860), D ? 0(2308), D ′ 1(2440), hc, η′c, X(3872), X(3940), Y (3940), Z(3930), Y (4260), Υ(1D), B1, B2, Bs2, Θ(1540)+, Θc(3099), Ξcc(3518), . . . Not all the states in the list have been confirmed (DsJ (2632), Θ(1540) +, Θc(3099)) and therefore we can ignore them. Other states (Ξcc(3518)) are baryons, deserving a dedicated analysis, and mesons with open (B1, B2, Bs2) or hidden beauty (Υ(1D)), that we do not discuss here. We only consider mesons with open and hidden charm. The wealth of information collected in recent years is impressive: not only the number of known states has nearly doubled, but a few experimental observations seem to challenge the current picture of mesons as simple quark-antiquark configurations. Therefore, it is important to search the signatures allowing us to assign a given state to a particular multiplet, so that the hints of exotic structures can be clearly interpreted. The next Sections are devoted to such aMy lady, this i