CERN’s LHCb experiment discovered the Xi-cc-plus, a new proton-like particle with two charm quarks, confirmed with 7 sigma significance during the 2024 LHC run.

Scientists at CERN’s LHCb experiment have discovered a new proton-like particle, the Xi-cc-plus, made of two charm quarks and one down quark, four times heavier than a proton. Detected using the upgraded LHCb detector during the LHC’s 2024 run, the particle was identified with 7 sigma significance, confirming it as the first new particle found after the upgrade. It is only the second baryon with two charm quarks ever observed and differs from a similar particle with an up quark, predicted to have a much shorter lifetime. The discovery provides key data for testing quantum chromodynamics and highlights the importance of detector advancements and international collaboration in high-energy physics.