XYZ physics at BESIII experiment

TL;DR

The BESIII experiment has made significant advances in studying exotic charmoniumlike states, discovering new particles and decay behaviors that shed light on the nature of $XYZ$ states in high-energy physics.

Contribution

This paper reports the discovery of the charged state $Z_c(3900)$, its decay behaviors, and potential connections between $Y(4260)$ and $X(3872)$, advancing understanding of exotic hadrons.

Findings

Discovery of $Z_c(3900)$ as a four-quark candidate

Observation of new decay modes of $Z_c(3900)$

Potential link between $Y(4260)$ and $X(3872)$

Abstract

With the ability to run above 4~GeV, the BESIII experiment located in the Beijing Electron Positron Collider (BEPCII), has becoming a pioneer in searching and studying charmoniumlike states ($XYZ$ particles). In 2013, BESIII Collaboration discovered a charged charmoniumlike state $Z_c(3900)$, which is confirmed immediately experimentally, and provides the best candidate for a four quark state by now. Continuous studies by BESIII Collaboration show new decay behavior of $Z_c(3900)$, and there are possible partner particle $Z_c(4020)/Z_c(4025)$ existing. By scanning above 4~GeV, BESIII also reveals the potential connection between $Y(4260)$ and $X(3872)$ for the first time, which may help us understand $XYZ$ particles in a new sight.