Ξcc++
The Xi double-charm baryon, denoted as, 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. is the first baryon discovered with two heavy quarks and a light quark. Its mass is 3621 MeV, nearly four times that of the proton.
It was identified when it disintegrated into a baryon and three lighter mesons, K, π and π.