Manchester physicists help confirm ultra-rare particle decay at CERN
Researchers from the University of Manchester contributed to the LHCb experiment's first evidence of the extremely rare B⁰_d → μ⁺μ⁻ decay, a result that tests the Standard Model and opens new avenues for probing physics at zeptometre scales.
Physicists from the University of Manchester have played a key role in the LHCb experiment at CERN’s Large Hadron Collider, which has reported the first evidence of the ultra-rare decay of a beauty-quark meson into two muons. The decay, expected to occur in roughly one in every 10 billion beauty particles, was observed with a statistical significance of 3.2 sigma, marking the initial step toward a definitive discovery.
The upgraded LHCb detector, capable of recording data at up to five times its previous rate, incorporates a silicon pixel Vertex Locator built largely by UK institutions. This component, positioned just five millimetres from the LHC beams, enables precise tracking of particle trajectories and decay points.
"The upgraded LHCb was a major undertaking – a fifteen-year design and construction project from a 1,900-member international collaboration," said Professor Chris Parkes, head of the Department of Physics and Astronomy at the University of Manchester. He added that the United Kingdom made the largest national contribution to the project and that the result is only the beginning of further studies with the upcoming High-Luminosity LHC.
"There has been a more than forty-year long search by physicists worldwide to observe this decay. It is a golden channel to observe the effects of new physics from beyond our current knowledge," said Professor Conor Fitzpatrick, deputy physics coordinator of the LHCb collaboration.
The measurement aligns with Standard Model predictions, but increased precision in future data sets could reveal deviations that hint at new particles or forces. The collaboration plans to collect a larger dataset through the early 2030s and is considering a further upgrade that would boost data-collection rates by an additional factor of ten.
"This is an important result and a beautiful example of how science advances. We upgrade our instruments and we see nature in greater detail," commented Professor Brian Cox, a particle physicist at the University of Manchester who was not involved in the study.
Funding for the experiment comes from the UK Science and Technology Facilities Council, part of UK Research and Innovation, with participation from ten UK universities and the STFC Rutherford Appleton Laboratory.