Observation of the Zcs(3985) strange four-quark meson
In the March 12th, 2021 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^+ (D_s^- D^(*0)+D_s^(*-) D^0) at an e^+ e^- center-of-mass energy of 4.68 GeV. The Zcs(3985) is observed to decay to a charged strange-charmed meson plus a neutral charmed meson, i.e., D_s^- D^(*0)+D_s^(*-) D^0, and has a mass of 3.98 GeV/c2. This is the first candidate for a tetra-quark meson containing hidden-charm with non-zero strangeness. This paper was selected as one of that issue’s and "Editors' Suggestion" and prominently featured on the APS synopsis website.