Speaker
Dr
Wei Chen
(University of Saskatchewan, Saskatoon)
Description
Many of the XYZ resonances observed by the Belle, Babar, CLEO and BESIII collaborations in the past decade are difficult to interpret as conventional quark-antiquark mesons, motivating the consideration of scenarios such as multi-quark states, meson molecules, and hybrids. After a brief introduction to QCD sum-rule methods, we provide a brief but comprehensive review of the mass spectra of the quarkonium-like tetraquark states $qQ\bar{q}\bar{Q}$, doubly charmed/bottomed tetraquark states $QQ\bar{q}\bar{q}$ and the heavy quarkonium hybrid states $\bar{Q}GQ$ in the QCD sum rules approach. Possible interpretations of the XYZ resonances are briefly discussed.
