Roberto D. Peccei

Best known for his work (with Helen Quinn) on the strong change parity (CP) problem. They showed that if there is an additional global chiral symmetry in nature, this symmetry restores CP conservation by driving the vacuum parameter associated with CP violation to zero. A consequence of this Peccei-Quinn (PQ) symmetry is the prediction that a very light and weakly coupled particle, known as the axion, exists. Peccei is among the earliest to understand the implications of the Kobayashi Maskawa model for CP violation in both Kaon and B-meson decays. With Chikashige and Mohapatra, he pointed out that real Nambu-Goldstone bosons (called Majorons) could exist in nature, associated with the breakdown of lepton number.