October 7, 2008

2008 Physics Nobel for Broken Symmetries

Yoichiro Nambu, Makoto Kobayashi, Toshihide Maskawa

COLLEGE PARK, MD – The 2008 Nobel Prize for Physics has been awarded to three physicists whose insights help to explain fundamental properties of the basic laws of nature. Half the prize goes to Yoichiro Nambu (University of Chicago) "for the discovery of the mechanism of spontaneous broken symmetry in subatomic physics." Half will be shared by Makoto Kobayashi (High Energy Accelerator Research Organization Tsukuba, Japan) and Toshihide Maskawa (Yukawa Institute for Theoretical Physics, Kyoto University) "for the discovery of the origin of the broken symmetry which predicts the existence of at least three families of quarks in nature."

The universe would be a bleak and boring place, and might not exist at all, if the laws of nature were perfectly symmetrical. The fact that most of the universe we see today is made of matter rather than a balance of mutually destructive matter and antimatter is the result of a broken symmetry that in turn makes stars, planets and life itself possible. Our understanding of the quarks and other particles that are the building blocks of matter relies on the broken symmetries uncovered by Nambu, Kobayashi and Maskawa.

"This year's prize recognizes two theoretical pillars of our modern understanding of the fundamental constituents of matter and the forces that act on them," explains APS Vice President Curtis Callan. "Nambu profoundly deepened our understanding of mass. His prescient work of the early 60s today allows us to explain how the proton and neutron (and, by extension, the atomic nucleus) can be made of nearly massless quark constituents and yet be very massive. Kobayashi and Maskawa developed a description of the intrinsic mass of the three generations of quarks which has been verified in spectacular experimental detail. It provides a framework for understanding why matter vastly dominates over anti-matter in our universe and also how neutrinos can change their character as they propagate to the Earth from the Sun."

All three of the 2008 Laureates have previously been recognized by the APS with the J. J. Sakurai Prize for Theoretical Particle Physics (Kobayashi and Maskawa in 1985, and Nambu in 1994). Nambu also won the 1970 APS Dannie Heineman Prize for Mathematical Physics. Nambu’s initial papers leading to his portion of the prize in appeared in APS journals nearly fifty years ago.

"We are pleased that Nambu's work was published in Physical Review Letters in 1960,” says APS Editor-in-Chief Gene Sprouse, “in the then nascent journal's second year of publication." The article is freely available online (see below).

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  Axial Vector Current Conservation in Weak Interactions
Yoichiro Nambu
Phys. Rev. Lett. 4, 380 - 382 (1960)

  1970 Dannie Heineman Prize for Mathematical Physics
Yoichiro Nambu
"For his diverse and profound contributions to theory, specifically for analysis of symmetry breaking into particle physics and of gauge invariance in the BCS theory of superconductivity, as examples of mathematical physics."

  1985 J. J. Sakurai Prize for Theoretical Particle Physics
Toshihide Maskawa and Makoto Kobayashi
"For their contributions to the theory of electroweak interactions through their general formulation of fermion mass matrix and their prescient inference of the existence of more than four flavors of quarks."

  1994 J. J. Sakurai Prize for Theoretical Particle Physics
Yoichiro Nambui
"For his many fundamental contributions to field theory and particle physics, including the understanding of the pion as the signaler of spontaneous breaking of chiral symmetry."