Quantum Chromodynamics, the theory of quarks and gluons, whose interactions can be
described by a local SU (3) gauge symmetry with charges called “color quantum numbers” …

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 …

Results are reported from an amplitude analysis of the B+→ D+ D-K+ decay. The analysis is
carried out using LHCb proton-proton collision data taken at s= 7, 8, and 13 TeV …

A large number of experimental discoveries especially in the heavy quarkonium sector that
did not meet the expectations of the until then very successful quark model led to a …

Many efforts have been made to reveal the nature of the overabundant resonant structures
observed by the worldwide experiments in the last two decades. Hadronic molecules attract …

The spectrum of hadrons is the manifestation of color confinement of quantum
chromodynamics. Hadronic resonances correspond to poles of the S-matrix. Since 2003 …

In the past two decades, a plethora of hadronic states beyond the conventional quark model
of qq ̄ mesons and qqq baryons have been observed experimentally, which motivated …

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 …

This review presents an overview of the remarkable progress in the field of heavy-quark
exotic hadrons over the past 15 years. It seeks to be pedagogical rather than exhaustive …