Dr. Alexey Nefediev (IJS): From ordinary to exotic hadrons: where are we heading?

For several decades, the quark model suggested 60 years ago was a powerful and successful tool to understand and predict properties of hadronic states in QCD. However, since 2003, when the Belle Collaboration discovered the X(3872), an enigmatic state in the spectrum of charmonium with the properties at odds with the predictions of the quark model, a new era in the spectroscopy of hadrons containing heavy quarks began. Since then, many new states in the spectrum of charmonium and bottomonium have been discovered that do not fit into the quark model scheme and qualify as exotic states. Most of them reside near strong open-flavour thresholds that leave imprint on their nature and properties. I will discuss various phenomena (coupled channels, multi-body dynamics, an interplay of the quark and hadronic degrees of freedom, and so on) to take into account in theoretical approaches to reliably extract the information contained in the data on exotic hadrons with heavy quarks and discuss particular examples of the effective field theory approach applied to exotic hadronic states.
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