CERN Discovers Ξ_cc^+ Subatomic Particle

Scientists at CERN's Large Hadron Collider have discovered a new subatomic particle, a heavier counterpart to the proton known as the Ξ_cc^+, which consists of two charm quarks and one down quark. The finding, announced at the Rencontres de Moriond conference, marks the first major discovery using the upgraded LHCb detector and was made possible through analysis of proton-proton collisions recorded in 2024.

The particle, a type of baryon four times heavier than a standard proton, was identified by its decay into three lighter particles: a lambda-charm baryon, a kaon and a pion. Researchers observed about 915 events forming a clear signal at a mass of 3,619.97 MeV/c², with a statistical significance exceeding 7 sigma, surpassing the 5-sigma threshold for a confirmed discovery. Unlike the stable proton, made of two up quarks and one down quark, this baryon is highly unstable, surviving for less than a trillionth of a second before decaying.

The discovery builds on a 2017 LHCb observation of a similar particle, the Ξ_cc^{++}, which features two charm quarks and one up quark. The new particle's predicted lifetime is up to six times shorter due to quantum effects, making it far more...