Researchers using the upgraded LHCb (Large Hadron Collider beauty) detector report evidence for a new particle called the doubly charmed baryon Ω_cc^+. In plain terms, this is a short-lived particle made from quarks that contains two charm quarks. The experimenters saw a clear peak in their data that they identify as this particle.

The search used proton–proton collisions recorded in 2024 with a total data size described as 6.3 inverse femtobarns — a standard way physicists count how many collisions were examined. The collisions had a center-of-mass energy of 13.6 teraelectronvolts (TeV). The team looked for Ω_cc^+ by reconstructing events where it would decay into an Ω_c^0 baryon and a positively charged pion (π^+). The Ω_c^0 itself was built from tracks identified as a proton (p), two negatively charged kaons (K^-), and a positively charged pion (π^+).

In the mass spectrum formed from Ω_c^0 and π^+ candidates, the analysis found a peaking structure with a global significance of 8.7 standard deviations (8.7σ). In particle physics, a significance above 5σ is normally taken as strong evidence that a signal is real and not a random fluctuation. The observed structure is reported to be consistent with originating from a particle that decays via the weak force, so the authors identify it as the doubly charmed baryon Ω_cc^+.

The measured mass of the new state is 3725.9 MeV/c^2 (about 3.726 GeV/c^2). The paper gives four separate uncertainties on that number: ±1.0 MeV/c^2 (statistical, coming from the finite size of the data sample), ±0.2 MeV/c^2 (systematic, from measurement and analysis effects), ±0.4 MeV/c^2 (a contribution related to an unknown lifetime that can bias the selection), and ±0.6 MeV/c^2 (an “external” uncertainty coming from the limited precision in the known masses of related baryons used in the analysis).