Nathan Isgur

Nathan Isgur (May 25, 1947 – July 24, 2001) was a theoretical physicist from the U.S. and Canada.

Isgur was born in South Houston, Texas and finished high school at South Houston High School. He was a scholarship student at Caltech. where his initial interest was in biology, but he moved toward physics and graduated with a B.Sc degree in 1968. Isgur began work on his doctorate at the University of California, Berkeley, but received his draft notice during his first year there. Denied a draft deferment to continue his education at Berkeley he went to Toronto in order to pursue his graduate studies and to avoid serving in a war he disagreed with on moral and political grounds. Isgur received a letter of introduction from Nobel Laureate Owen Chamberlain at Berkeley, to R.E. Pugh, at the University of Toronto, who took him on as a graduate student. Isgur received a Ph.D. degree in particle theory from Toronto in 1974.

Isgur eventually became a Canadian citizen due to his inability to travel, having been unable to renew his U.S. passport due to his draft status, and because of his position as a war resister. This situation continued to inhibit his ability to travel to the United States until President Jimmy Carter issued a blanket amnesty for all draft resisters.

After completion of his Doctorate, Isgur was granted a Natural Sciences and Engineering Research Council Fellowship, which allowed him to stay at Toronto as a post-doctoral candidate. He was hired as an assistant professor in the Department of Physics in 1976 in recognition of his outstanding merit by department head Robin Armstrong, even though he had not been able to travel to gain experience outside the Department owing to passport difficulties. In 1975 Isgur published on the mixing angle of pseudo-scalar mesons due to annihilation into gluons. He embarked on a long collaboration with Gabriel Karl from the University of Guelph, involving the study of excited baryons in quark models. The principal physical idea of the model was taken from quantum chromodynamics: the forces between quarks are flavour-independent. This idea gave rise to their "QCD-improved" quark model.

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