BESIII: Observation of the Zcs(3985) strange four-quark meson

In the last issue of Physical Review Letters, the BESIII collaboration reports the discovery of an exotic multi-quark structure, dubbed the Zcs(3985), that is produced in the process of e+ e-→K+ (Ds- D*0+Ds*-D0) at a center-of-mass energy of 4.68 GeV, at BEPCII collider.

 

This is the first candidate for a tetra-quark meson containing hidden-charm with non-zero strangeness and has a mass of 3.98 GeV/c2.

The BESIII discovery emerged from analyses of data sets taken at five center-of-mass energy points ranging from 4.628 to 4.698 GeV in 2020 with a total integrated luminosity of 3.7 fb^-1.

Studies of exotic hadron states provide unique access to details of the non-perturbative effects and color confinement mechanisms in the QCD theory. The existence of hidden-charm tetraquarks with non-zero strangeness was predicted by many theoretical models, but until now, no definitive experimental observations have been reported.

 

The BESIII Collaboration has about 500 members from 72 institutions in 15 countries, including researchers of the University and INFN Section of Ferrara, Perugia, Torino, and of the National Laboratory of Frascati.

Further reading: http://bes3.ihep.ac.cn/doc/4187.html

PRL publication: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.126.102001