Stanley Mandelstam

Stanley Mandelstam (12 December 1928 – 23 June 2016) was a South African-born American theoretical physicist of Jewish descent. He introduced the Mandelstam variables into particle physics in 1958. It was a coordinate system for creating his double dispersion relations. 
He was the Professor of Mathematical Physics at the University of Birmingham (1960-63), the Professeur Associé at Université Paris-Sud (1979–80; 1984–85) and the Professor of Physics at the University of California, Berkeley from 1963 until his death and was also the Professor Emeritus from 1994 until his death.