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LHCb Confirms Doubly Charmed Ξcc⁺ Baryon in 7σ Discovery

The upgraded LHCb detector using 2024 Run‑3 data pins the particle’s mass, closing a 20‑year SELEX anomaly.

Overview

  • The new baryon contains two charm quarks and one down quark, making it about four times heavier than a proton.
  • Analysis finds a clear peak of roughly 915 events at a mass of 3619.97 MeV/c² with discovery-level significance.
  • This is the first particle identified after LHCb’s 2023 upgrades and only the second ever baryon with two heavy quarks observed.
  • The result places the Ξcc⁺ near the mass of its 2017 partner Ξcc⁺⁺, contradicting the much lower value reported by SELEX in 2002.
  • The particle’s lifetime is predicted to be up to six times shorter than its partner, underscoring the challenge of detection and offering new tests for quantum chromodynamics.