Heavy Flavour Spectroscopy

TL;DR

This paper reviews recent experimental progress in heavy flavour spectroscopy, focusing on exotic hadronic states beyond the traditional quark model, including new particles, decay modes, and evidence for tetraquarks and pentaquarks.

Contribution

It provides a comprehensive overview of experimental discoveries related to XYZ particles, highlighting new states, decay channels, and evidence for exotic multiquark configurations.

Findings

Observation of new decay modes of Y(4230)

Evidence for neutral isospin partners of Z_{cs}

Discovery of tetraquark and pentaquark candidates

Abstract

The discovery of hadronic states beyond the conventional two-quark meson and three-quark baryon picture in the last two decades is one of the most amazing accomplishments in fundamental physics research. We review the experimental progress on the study of the exotic states (also known as the XYZ particles) beyond the conventional quark model. We give a general review and then focus on the lineshape measurement of the X(3872), observation of new decay modes of the Y(4230) and new vector charmoniumlike states Y(4500) and Y(4790), evidence for the neutral isospin partners of the charged charmoniumlike $Z_{cs}$ states, discoveries of the tetraquark state candidates with four different flavours or two-pairs of charm-anticharm quarks and the pentaquark states.