Exotic hadrons with heavy quarks

For several decades, the quark model suggested 60 years ago as a classification scheme for multiquark states had been 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 how one can extract the information contained in the experimental data on exotic hadrons with heavy quarks and employ this information to make predictions for not yet observed hadrons and their properties.