Newest results on XYZ states at BESIII

TL;DR

This paper reviews recent results from BESIII on XYZ states, including precision measurements and first observations, advancing understanding of exotic charmonium-like particles.

Contribution

It presents new experimental findings on XYZ states, including the first observation of X(3872) in radiative decays and detailed measurements of Y and Z states.

Findings

First observation of X(3872) in radiative decays

Precision cross-section measurements of Y states

Completion of isospin triplet observations for Zc states

Abstract

The BESIII experiment at BEPCII at IHEP in Beijing/China has collected the world largest data sets in the $\tau$-charm region and it is well suited to cover a rich hadron physics programme, including charmonium and open-charm spectroscopy, $R$-scan or electromagnetic form factor measurements, and many more. In particular, the unique data sets between 3.8 and 4.6\,GeV allow for discoveries and precision measurements of the interesting charmonium-like (exotic) `XYZ' states. The recently published precision cross-section measurement for $Y$ states is discussed as well as the first observation of the $X(3872)$ in radiative decays, also the completion of the two observed isospin triplets $Z_{\rm c}(3900)$ and $Z_{\rm c}(4020)$ is briefly summarised.