Scientists from the University of Manchester have played a leading role in the discovery of a new subatomic particle at CERN's Large Hadron Collider (LHC). The particle, known as the Ξcc⁺ (Xi‑cc‑plus), is a new type of heavy proton-like particle containing two charm quarks and one down quark.

The result is the first particle discovery made using the upgraded LHCb detector, a major international project involving more than 1,000 scientists across 20 countries. The UK made the largest national contribution to the upgrade, with significant leadership from Manchester.

The newly observed Ξcc⁺ is a heavier relative of the proton, which was famously discovered in Manchester by Ernest Rutherford and colleagues in 1917–1919. The proton contains two up quarks and a down quark. Details of the Ξcc⁺ discovery were presented at the Rencontres de Moriond Electroweak conference.

The new discovery replaces the up quarks with their heavier relatives, the charm quarks. It also extends a legacy begun in the 1950s, when Manchester physicists were the first to identify a member of the Ξ (Xi) particle family.

Professor Chris Parkes, head of the University's Department of Physics and Astronomy, led the international collaboration during the installation and first operation of the LHCb Upgrade detector. He also led the UK contribution to the project for over a decade, from approval through to delivery.