TSUKUBA, Japan - Makoto Kobayashi, 64, Professor Emeritus of KEK and executive director of the Japan Society for the Promotion of Science, was awarded a 2008 Nobel Prize for Physics for the theory to explain the origin of the broken symmetry which predicts the existence of at least three families of quarks in nature. He shares the award with Toshihide Maskawa, Professor of Kyoto Sangyo University in Kyoto, and Yoichiro Nambu, Professor Emeritus of University of Chicago, who was awarded the prize for the discovery of the mechanism of spontaneous symmetry breaking in subatomic physics.
Kobayashi is a particle physics theorist at KEK since 1979. Kobayashi is the first Nobel laureate directly associated with KEK. He became the Director of the Institute of Particle and Nuclear Studies (IPNS) in 2003, and Professor Emeritus in 2006.
"We are extremely proud," said KEK Director General Atsuto Suzuki. "not only because he has been associated with our laboratory for three decades, but that KEK has contributed to verify the matter-antimatter asymmetry predicted by the Kobayashi-Maskawa theory in great detail through our experiments."
The Belle experiment with the KEKB accelerator has produced billions of particles called "B mesons" and "anti B mesons". A meson is a type of composite particle made of a pair of quark and anti-quark. A B meson contains a specific type of quark called "bottom".
In 2001, Belle observed large matter-antimatter asymmetry in B meson decays as expected from the Kobayashi-Maskawa theory. The experiment has been accumulating more data and the confidence level of the Kobayashi-Maskawa theory has been further increased.
Kobayashi played a significant role for the success of the Belle experiment. With his strong leadership as the Director of the IPNS, the Belle experiment stayed as one of the most prominent high energy physics experiments in the world over a decade.
"Quarks are the most basic building block of matter," explains Kobayashi. "In 1973, when Maskawa and I published a paper, there were only three types of quarks conceived in particle physics. We investigated how adding three more types of quarks would solve the puzzle of matter-antimatter asymmetry observed in the decays of K mesons."
After receiving his Ph.D at the Graduate School of Nagoya University, Kobayashi started his career as a research associate at Kyoto University. During his work at Kyoto University, Kobayashi published a paper "CP Violation in the Renormalizable Theory of Weak Interaction", written with Toshihide Maskawa, which is the second most cited high energy physics paper of all time as of 2007.
"The Nobel Prize in Physics for Makoto Kobayashi and his colleagues is well deserved," says Persis Drell, Director of Stanford Linear Accelerator Center. "His visionary intuition about how nature might be hiding its secrets ultimately led to the development of the extremely successful B factory experiments at SLAC and KEK."
Kobayashi and Maskawa explained the broken symmetry of matter and antimatter within the framework of the Standard Model, the basic theory of how the universe operates, by predicting the existence of a third generation of quarks then unknown. CP Violation, meaning symmetry breaking of charge and parity, was precisely confirmed by the two particle detectors: BaBar at Stanford Linear Accelerator Center (SLAC), USA, and Belle at KEK, Japan.
The other Nobel laureate Yoichiro Nambu revolutionized modern scientific ideas about the nature of the most fundamental particles by introducing his description of spontaneous symmetry breaking into particle physics in the 1960's. His theories form an essential cornerstone of the Standard Model, which explains in a unified way three of the four fundamental forces of nature: strong, weak and electromagnetic. He has significantly influenced the development of Quantum Chromodynamics, a theory that describes certain interactions between quarks and between protons and neutrons.
Pier Oddone, the Director General of Fermilab, commemorates: "Today's Nobel Prize recognizes the pioneering development of a picture of nature that has had a major impact on physics at Fermilab and at other laboratories around the world."
In physics, "symmetry" means that a physical situation will be unchanged under certain transformations. One of the important examples of broken symmetry arose immediately after the Big Bang. The most basic form of the Big Bang Theory predicts that equal amounts of matter and antimatter should have been created at the early stage of the universe. They should annihilate each other, but there was some matter remained. This is the broken symmetry thought to be responsible for the visible parts of the universe. New particle accelerators, such as LHC at CERN in Geneva, proposed more advanced accelerators such as upgraded KEKB and International Linear Collider, are expected to unravel some of the mysteries of the universe.
Albrecht Wagner, the Director General of DESY says "My sincere congratulations to our colleagues Kobayashi and Maskawa who have developed their theory many years ago and whose work has recently became a major focus for the experimental work at KEK and SLAC. These state-of-the-art accelerators and detectors have shown the beauty and validity of the theory with an astonishing accuracy."
Francois Le Diberder, spokesperson for the BaBar experiment, and Hassan Jawahery, former spokesperson of BaBar, jointly speak of their appreciation for Kobayashi and Maskawa's work: "The BaBar collaboration extends its warmest congratulations to KEK and the whole Japanese Particle Physics community for receiving the award of the 2008 Nobel Prize to Prof Kobayashi and Prof Maskawa for their breakthrough leading at once to the explanation of CP violation and to the prediction of the third family of quarks and leptons. The BaBar and Belle collaborations' most important achievement is the experimental validation of the CP violation model they put forward."