Physicists at CERN's LHCb experiment reported the discovery of the doubly charmed baryon Ξcc⁺ in March 2026. This particle contains two charm quarks and one what?

Subatomic particles known as baryons are composite particles made up of three quarks. There are six types of quarks in the Standard Model of particle physics: up, down, strange, charm, bottom, and top. The recent discovery of the doubly charmed baryon Ξcc⁺ by physicists at CERN's LHCb experiment in March 2026 revealed a fascinating new member of this family. This particle is composed of two charm quarks and one down quark.

This particular combination is significant because it represents a baryon with two heavy charm quarks. Protons, for example, are composed of two up quarks and one down quark. The Ξcc⁺ is a much heavier cousin of the proton, weighing roughly four times as much due to the significantly greater mass of charm quarks compared to up quarks. The observation of such a particle provides a unique opportunity to study the strong nuclear force, which binds quarks together, under extreme conditions involving multiple heavy quarks. This discovery also confirms theoretical predictions and helps refine our understanding of quantum chromodynamics.

The upgraded LHCb detector at CERN was crucial in identifying this elusive particle. Particles like the Ξcc⁺ are extremely unstable, existing for only about 45 femtoseconds before decaying into lighter particles, making their detection a considerable experimental challenge. The successful observation of the Ξcc⁺, which was spotted through its decay products from proton-proton collisions recorded in 2024, expands the known "particle zoo" and further strengthens the validity of the Standard Model of particle physics.