Louis Michel (French pronunciation: [lwi miʃɛl]; 1923–1999) was a French mathematical physicist at the Institut des Hautes Études Scientifiques (IHÉS).[1] He was born in Roanne, in the Loire department in central France, on 4 May 1923, and died in Bures-sur-Yvette (Essonne), in the Île-de-France region, on 30 December 1999. His name is associated with Michel parameters describing the phase space distribution of leptonic decays of charged leptons, the Bargmann–Michel–Telegdi equation describing spin evolution in a magnetic field,[2] and the Michel–Radicati theory for the SU(3) octet,[3][4]