A brief mention today of a new measurement from the BABAR experimental collaboration, which tests lepton universality (to be explained below) and finds it wanting.
The Basic Story (Slightly Oversimplified)
Within the Standard Model of particle physics (the equations that describe and predict the behavior of all of the known particles and forces), the effects of the weak nuclear force on the three leptons — the electron, the muon and the tau — are all expected to be identical. This called “lepton universality”. Continue reading