Steven C. Frautschi (/ˈfraʊtʃi/; born December 6, 1933) is an American theoretical physicist, currently professor of physics emeritus at the California Institute of Technology (Caltech).
[1] Frautschi graduated from Harvard College in 1954 and received his PhD from Stanford University in 1958, having written his dissertation on PC conservation in strong interactions and wide angle pair production and quantum electrodynamics at small distances, under the supervision of Sidney Drell.
Frautschi's most well known contribution to strong-interaction theory was the statistical bootstrap, a prediction that the number of hadronic states grows exponentially with energy.
(This S-matrix approach to the strong interactions was largely abandoned by the particle physics community in the 1970s in light of quantum chromodynamics.)
In 1961, with Donald R. Yennie and Hiroshi Suura, he elucidated the role of infrared photons properly summed in high-energy QED.