LHCb sees rare hyperon decay first observed by HyperCP

Some thirteen years ago HyperCP observed what was then the rarest baryon decay ever: Sigma-plus -> p + mu+ + mu-. What was interesting was the cluster of the dimuon mass about 214 MeV, suggesting a new light particle. LHCb does not see it, although there limit is consistent with HyperCP's observation. HyperCP only saw three events; LHCb has more: 13. So in the future they may make a more definitive statement. Read the burb below from the March 2018 edition of the CERN Courier.