YOISHIRO NAMBU
Prof. Yoishiro Nambu was born in 1921 in Tokyo. He received his
Doctor of Science degree from the University of Tokyo in 1952.
During the late 40's,
when the subject of quantum electrodynamics
was being formulated, he was associated with Prof. S. Tomonaga.
In 1952, he was invited to the Institute for Advanced Study in
Princeton.
He became Professor of Physics at the University of
Chicago in 1958, where, from 1974 to 1977, he was also
Chairman of the Department of Physics.
Nambu has made many important contributions to the development
of elementary particle theory, including the introduction of the
concept of
spontaneous symmetry breaking for which he shared the 2008 Physics Nobel prize.
SPONTANEOUS SYMMETRY BREAKING IN STRONG INTERACTIONS
The spontaneous symmetry breaking model of hadron mass generation was
developed by Nambu, together with Jona-Lasinio.
This model is based on an
analogy with the BCS theory of superconductivity. The modern version of the
N(ambu)--J(ona)-L(asinio) Model
is a low energy approximation to Quantum
Chromodynamics. It also gives important insight into the nucleon-nucleon
force,
both in free space and in nuclei. Some features of nuclei, such as the
approximate validity of the interacting boson model,
appear to be due to a
manifestation of spontaneous symmetry breaking due to the nuclear pairing
interaction.
The NJL model was originally proposed around 1960, before it was realized that
nucleons are made up of three quarks.
However, Nambu. with Han, did some
pioneering work along these lines concerning gluons.
GLUONS AS CARRIERS OF STRONG INTERACTIONS
It is well known that photons are carriers of the force between electric
charges. Nambu and Han generalized this idea to strong interactions,
and
proposed that the force between quarks is carried by gluons. In the original
version of Nambu's work,
the quarks were taken to have integral charges, but
that was later corrected by Gell-Mann who introduced fractional charges.