The quark model was formulated in 1964 to classify mesons as bound states made of a
quark–antiquark pair, and baryons as bound states made of three quarks. For a long time all …

The past seventeen years have witnessed tremendous progress on the experimental and
theoretical explorations of the multiquark states. The hidden-charm and hidden-bottom …

Multiquark resonances are undoubtedly experimentally observed. The number of states and
the amount of details on their properties have been growing over the years. It is very recent …

In the past decade many charmonium-like states were observed experimentally. Especially
those charged charmonium-like Z c states and bottomonium-like Z b states cannot be …

A golden age for heavy-quarkonium physics dawned a decade ago, initiated by the
confluence of exciting advances in quantum chromodynamics (QCD) and an explosion of …

For many decades after the invention of the quark model in 1964 there was no evidence that
hadrons are formed from anything other than the simplest pairings of quarks and antiquarks …

Quantum chromodynamics (QCD), the generally accepted theory for strong interactions,
describes the interactions between quarks and gluons. The strongly interacting particles that …

Pentaquark baryons are a natural expectation of an extended picture of hadrons where
quarks and diquarks are the fundamental units. The parity/mass pattern observed, when …

Following the recent confirmation of the Z+(4430) resonance with JPG= 1++, we have re-
examined the model of S-and P-wave tetraquarks. We propose a “type-II” diquark …

The past decade witnessed a remarkable proliferation of exotic charmonium-like
resonances discovered at accelerators. In particular, the recently observed charged states …