From http://status.hackerposse.com/url/24447 on Mastodon: # CMSPaper 1216: The η (=eta) is a special particle.This paper finds a new way the η can decay: into four muons. This is important because it measures muon-photon interactions, and quite accurately at that. That is a precision test of theory predictions, including some inputs to the muonic magnetic dipole moment.…