The recent discovery of a new particle marks a significant milestone in particle physics, taking place at CERN's upgraded LHCb detector. This achievement is the result of a collaborative effort involving over 1,000 scientists from 20 countries, with the United Kingdom, particularly Manchester, playing a pivotal role.
A Heavier Proton Relative
The newly identified particle, Ξcc⁺, belongs to the same family as the proton, first discovered in Manchester by Ernest Rutherford and his team between 1917 and 1919. Unlike the proton, which consists of two up quarks and one down quark, the Ξcc⁺ contains heavier charm quarks in place of the up quarks.
This finding is a continuation of Manchester's rich legacy in particle physics. In the 1950s, researchers at the university were the first to discover a member of the Ξ (Xi) particle family, paving the way for groundbreaking discoveries such as this one.
Manchester's Contribution to the LHCb Upgrade
Professor Chris Parkes, head of the Department of Physics and Astronomy at the University of Manchester, led the international team during the installation and initial operations of the upgraded LHCb detector. He has overseen the UK's involvement in this project for over a decade, guiding it from its inception to completion.
The Manchester LHCb team was instrumental in designing and constructing key components of the upgraded tracking system, including silicon pixel detector modules fabricated in the university's Schuster Building. These components are essential for accurately tracking particle decays and identifying signals like the Ξcc⁺.
Professor Parkes emphasized, "Rutherford's groundbreaking gold-foil experiment in a Manchester basement revolutionized our understanding of matter. Today's discovery builds on that legacy, showcasing the power of state-of-the-art technology at CERN and the remarkable contributions from the UK and Manchester."
Advanced Detection Technology
Dr. Stefano De Capua from The University of Manchester spearheaded the production of the silicon detector modules, likening the detector's function to that of a high-speed camera.
"This detector acts like a 'camera' that captures images of particles produced at the LHC, taking photographs at an astonishing rate of 40 million times per second. It employs a specially designed silicon chip, which also has applications in medical imaging," he explained.
Identifying the Ξcc⁺ Particle
The Ξcc⁺ was detected by analyzing its decay into three lighter particles (Λc⁺, K⁻, π⁺) during proton-proton collisions at the LHC in 2024, the first year the upgraded LHCb experiment operated at full capacity.
A total of approximately 915 decay events were recorded, corresponding to a mass of 3619.97 MeV/c², aligning with predictions based on a previously identified related particle, the Ξcc⁺⁺.
Future Prospects for CERN and Manchester
Looking forward, the University of Manchester is set to continue its leadership role in the next phase of the LHC program, known as LHCb Upgrade 2, which will utilize the High-Luminosity LHC accelerator to collect more data and investigate rare particles in greater depth.
Details regarding the Ξcc⁺ discovery were shared at the Rencontres de Moriond Electroweak conference, highlighting the ongoing pursuit of knowledge in particle physics.