 |
| Nathan
Isgur |
Physicists have difficulty studying
individual quarks, because these smallest
particles of matter are always bound
together in pairs or groups of three.
The heaviest of the six quarks found
in nature have been the most baffling.
But such studies are easier now, thanks
to a method for understanding quarks
developed in the early 1990s. "Heavy
quark effective theory" enables physicists
to deduce the individual behavior
of one type of quark (the bottom quark)
by showing how its properties can
be directly inferred from measurements
of another type (the charm quark).
The six quarks identified in nature
(in order of increasing mass) are
distinguished by the terms up, down,
strange, charm, bottom, and top. The
heaviest (the top quark) is about
100,000 times the mass of the lightest
(the up quark). The theory is based
on seven years of theoretical work
by Nathan Isgur of Thomas Jefferson
National Laboratory and Mark Wise
of California Institute of Technology,
and a third researcher working independently.
Scientific Impact:
This theory made it easier to study
bottom quarks and pairs of them—important
particles in ongoing studies of why
the universe favors matter over its
mirror image, antimatter. These papers
also have generated thousands of other
papers that offer new insight into
another theory describing the "strong
force" that binds subnuclear particles
such as quarks.
Social Impact: These
studies help answer questions about
the constituents and history of the
universe, extending human understanding
of nature and contributing to improvements
in science education. In addition,
although basic research is by definition
a search for new knowledge without
regard to its practical implications,
such work often contributes to technologies
with commercial value; examples include
computers, lasers, and cancer treatments.
Reference: N. Isgur
and M.B. Wise, Phys. Lett.
B232, 113 (1989); 237, 527 (1990);
Heavy Quark Physics, Aneesh
V. Manohar, Mark B. Wise, Cambridge
University Press (2000).
URL:
http://www.jlab.org/div_dept/theory/favorites/spectroscopy.html
Technical Contact:
Linda Ware, ware@jlb.org
Press Contact: Jeff
Sherwood, DOE Office of Public Affairs,
202-586-5806
SC-Funding Office:
Office of High Energy and Nuclear
Physics |
