re "what models people like to explain": There was some good discussion of lepton universality violation at the end of the announcement talk. tl;dr - electrons

re "what models people like to explain": There was some good discussion of lepton universality violation at the end of the announcement talk. tl;dr - electrons and muons are leptons, but what if they don't interact with photons the same way? (ie the rules of physics aren't universal to all leptons)