Possible anomalies in thebb¯spectrum and their theoretical interpretation

Recently, CESR experiments found anomalies in the bb¯ spectrum: (i) the mass difference between Υ(4S) and Υ(5S) is larger than expected from the potential models, (ii) a possible resonance structure is found just above Υ(4S). We show that quarkonium-hybrid mixing (QHM) gives a possible interpretation of these anomalies. The QHM model also improves the prediction of ${\Gamma }_{\mathrm{ee}}$, ${\Gamma }_{\mathrm{total}}$, and masses for cc¯ and bb¯ states above threshold.