Scientists from the University of Manchester have played a pivotal role in the groundbreaking discovery of a new subatomic particle at CERN’s Large Hadron Collider (LHC). The particle, named Ξcc⁺ (Xi-cc-plus), represents a novel class of heavy proton-like particles, comprising two charm quarks and one down quark. This discovery marks a significant milestone for the upgraded LHCb detector, a global initiative involving over 1,000 scientists from 20 countries, with the UK making the largest national contribution, spearheaded by Manchester.
The announcement comes as the newly observed Ξcc⁺ emerges as a heavier counterpart to the proton, famously discovered in Manchester by Ernest Rutherford and his team between 1917 and 1919. While the proton consists of two up quarks and a down quark, the Ξcc⁺ replaces the up quarks with their heavier charm relatives, extending a legacy that began in the 1950s when Manchester physicists first identified a member of the Ξ (Xi) particle family.
Manchester’s Leading Role in Particle Physics
Professor Chris Parkes, head of the University’s Department of Physics and Astronomy, led the international collaboration during the installation and initial operation of the LHCb Upgrade detector. He has also been at the helm of the UK’s contribution to the project for over a decade, from its inception to fruition. The Manchester LHCb group was instrumental in designing and constructing key components of the upgraded tracking system, including the silicon pixel detector modules assembled in the University’s Schuster Building.
Professor Parkes remarked, “Rutherford’s gold-foil experiment in a Manchester basement transformed our understanding of matter, and today’s discovery builds on that legacy using state-of-the-art technology at CERN. Both milestones demonstrate just how far curiosity-driven research can take us. This discovery showcases the extraordinary capability of the upgraded LHCb detector and the strength of UK and Manchester contributions to the experiment.”
Technological Innovations and Applications
Dr. Stefano De Capua from The University of Manchester, who led the silicon detector module production, explained, “The detector is a form of ‘camera’ that images the particles produced at the LHC and takes photographs 40 million times per second. It utilises a custom-designed silicon chip that also has a variant for use in medical imaging applications.”
The Ξcc⁺ particle was identified through its decay into three lighter particles (Λc⁺ K⁻ π⁺), recorded during proton-proton collisions at the LHC in 2024, marking the first year of full operation of the LHCb Upgrade experiment.
A clear peak of around 915 events was observed at a mass of 3619.97 MeV/c², consistent with expectations based on a previously discovered partner particle, the Ξcc⁺⁺.
Resolving Long-standing Scientific Questions
This observation resolves a question that had remained open for more than two decades since an unconfirmed claim of the observation of this particle was made. The particle has now been discovered by LHCb at a mass incompatible with this earlier claim and a mass that is compatible with the theoretical expectations based on the partner particle.
In the next phase of the LHC programme, The University of Manchester is playing a leading role in LHCb Upgrade 2, which is planned to take advantage of the High-Luminosity LHC accelerator. Details of the Ξcc⁺ discovery are presented at the Rencontres de Moriond Electroweak conference.
Implications for Future Research
The move represents a significant leap forward in particle physics, promising to deepen our understanding of the fundamental forces that govern the universe. The discovery of the Ξcc⁺ not only enriches the particle zoo but also sets the stage for future explorations into the behavior of quarks and the strong force.
As the scientific community digests these findings, the implications for both theoretical and experimental physics are profound. The upgraded LHCb detector’s success in identifying the Ξcc⁺ underscores the importance of international collaboration and cutting-edge technology in advancing our knowledge of the universe.
Looking ahead, researchers are eager to explore the potential applications of these technological advancements beyond particle physics, particularly in fields like medical imaging, where the precision and speed of the silicon detectors could revolutionize diagnostic techniques.
The discovery of the Ξcc⁺ at CERN’s LHC is a testament to the enduring legacy of Manchester’s contributions to science and the relentless pursuit of knowledge that continues to drive the field of particle physics forward.
