Hamilton Colloquium Series: A. J. Stewart Smith, Princeton; “The Path to CP Violation: Remembering Val Fitch and Jim Cronin in Princeton”

Thu, Dec 8, 2016, 4:00 pm to 5:00 pm
Jadwin A10

Within the past year and a half we have lost Val Fitch and Jim Cronin, two of Princeton’s greatest physicists. Their 1964 discovery of CP Violation in the decays of the long-lived neutral K meson, referred to at the time as “the Princeton Effect,” was a complete surprise, right out of the blue, that defied any and all explanation. The mystery was solved 37 years later when experiments at Stanford and Tsukuba, Japan observed CP violation in the B meson system, conclusively confirming the bold and prescient proposal of Kobayashi and Maskawa, put forward in 1973 when only three quarks were known, that CP violation would occur “naturally” in a 6-quark world. All measurements to date agree with this simple picture, in which CP violation results from interference between two amplitudes related by a single complex phase in the quark couplings. In cosmology, however, the CP puzzle lives on as strong as ever! The “Princeton effect” pointed the way to Sakharov’s observation that CP violation is necessary to explain the disappearance of antimatter from the early universe, but is ten billion times too small. So paradoxically, we understand very well a tiniest manifestation of CP violation, but not at all the gigantic effect that allows our universe to exist. In this talk, I’d like to pay tribute to Val and Jim with a personal and Princeton-centric account of the remarkable experiences and serendipities that drew these remarkable people together to make one of the most profound discoveries in particle physics. Their magic collaboration lasted less than two years, but their names will always be linked together in legend.