Murray Gell-Mann

Murray Gell-Mann ( /ˈmʌriː ˈɡɛl ˈmæn/; born September 15, 1929) is an American physicist who received the 1969 Nobel Prize in physics for his work on the theory of elementary particles. He is the Robert Andrews Millikan Professor of Theoretical Physics Emeritus at Caltech, a Distinguished Fellow and co-founder of the Santa Fe Institute, Professor in the Physics and Astronomy Department of the University of New Mexico, and the Presidential Professor of Physics and Medicine at the University of Southern California.

He formulated the quark model of hadronic resonances, and identified the SU(3) flavor symmetry of the light quarks, extending isospin to include strangeness, which he also discovered. He developed the V-A theory of the weak interaction in collaboration with Richard Feynman. He created current algebra in the 1960s as a way of extracting predictions from quark models when the fundamental theory was still murky, which led to model-independent sum rules confirmed by experiment.

Gell-Mann, along with Maurice Lévy, developed the sigma model of pions, which describes low energy pion interactions. Modifying the integer-charged quark model of Han and Nambu, Fritzsch and Gell-Mann were the first to write down the modern accepted theory of quantum chromodynamics, although they did not anticipate asymptotic freedom. In 1969 he received the Nobel Prize in physics for his contributions and discoveries concerning the classification of elementary particles and their interactions.

Gell-Mann is responsible for the see-saw theory of neutrino masses, that produces masses at the inverse-GUT scale in any theory with a right-handed neutrino, like the SO(10) model. He is also known to have played a large role in keeping string theory alive through the 1970s and early 1980s, supporting that line of research at a time when it was unpopular.