Overview
- The Xi_cc^+ baryon contains two charm quarks and one down quark, making it roughly four times heavier than a proton and the isospin partner of the Xi_cc^++ seen in 2017.
- LHCb reconstructed the state in Run 3 proton–proton collisions with a statistical significance of 7 sigma after 2023 detector upgrades sharpened sensitivity to fleeting decays.
- Its measured mass lies near its Xi_cc^++ counterpart at about 3.62 GeV/c^2, contradicting the lower-mass candidate reported by the SELEX experiment in 2002.
- The particle is predicted to have a lifetime up to six times shorter than Xi_cc^++, which helps explain why earlier experiments failed to observe it.
- Announced at the Moriond conference, the finding is LHCb’s first post‑upgrade particle discovery, raises the LHC hadron tally to 80, and provides fresh input for testing QCD models.