Ξcc++

The Xi double-charm baryon, denoted as $$\Xi_{\rm{cc}}^$$, is a Xi baryon composed of two charm quarks and one up quark.

Its discovery by the LHCb Collaboration was announced on 6 July 2017 in Venice, Italy, at the European Physical Society Conference on High Energy Physics. $$\Xi_{\rm{cc}}^$$ is the first baryon discovered with two heavy quarks (charm and/or bottom) and a light quark. Its mass is 3621 MeV, nearly four times that of the proton.

It was identified when it disintegrated into a $$\Lambda_{\rm{c}}^$$ baryon and three lighter mesons, K$5$, π$1$ and π$–$.