Exes and why Z? Some charming and beautiful observations

Abstract

Threshold enhancements like the X(4660) and depletion effects as the X(4260) are listed as c-cbar resonances in the Particle Data Group tables. We will discuss these observations, and present a list of further c-cbar enhancements, which are more likely to represent true vector charmonium excitations. We will furthermore discuss the importance of the observed Z resonances, viz. Z(4050), Z(4250), and Z(4430), for the family of charm-strange mesons. Another piece of very important information that can be extracted from the present data is the universal, flavor independent frequency of 190 MeV for mesons, due to the quark-antiquark oscillations within the glue environment. Finally, we will show hints from the data at a further flavor-independent quantity, having a value of 76 +-2 MeV, the origin of which is not yet understood. Talk available at http://cft.fis.uc.pt/eef/Frascati2010start.htm