![Apparatus used to regenerate short-lived K mesons for the CP experiment.](images/40.jpg) |
Apparatus
used to regenerate short-lived
K mesons for the CP experiment. |
Early in the evolution of the universe,
matter and its mirror image, antimatter,
were equally abundant; but today,
antimatter is rare, for reasons not
fully understood. A recent observation
at Fermi National Accelerator Laboratory
lessened the mystery somewhat. The
1999 experiment focused on mesons,
short-lived pairings of a quark particle
and the corresponding anti-quark.
The researchers observed direct charge-parity
(CP) violation in the decay of K mesons,
or kaons, supporting the picture of
CP violation provided in the Standard
Model, physicists' current theory
of matter and the forces of nature.
The phenomenon of CP violationwhich
shows that matter and antimatter do
not always behave symmetricallywas
first discovered in kaon processes
at Brookhaven National Laboratory
in 1964, resulting in a 1980 Nobel
Prize for Val Fitch and James Cronin.
The definitive nature of the Fermilab
result was dramatic and unexpected.
Scientific Impact:
The result established the existence
of direct CP violation beyond reasonable
doubt and eliminated the long-standing
hypothesis of a proposed "superweak"
interaction as its source. This was
a significant advance in understanding
of the asymmetry in the behavior of
matter and antimatter.
Social Impact: CP
violation may be responsible for the
survival of matterincluding
humansand the disappearance
of antimatter. Thus, this research
extends human understanding of the
origin and history of the universe
and contributes to improvements in
science education.
Reference: Phys.
Rev. Lett. 83, 22 (1999). hep-ex/9905060.
URL: http://www.aip.org/physnews/graphics/html/violate.htm
http://kpasa.fnal.gov:8080/public/epsprime/press_release.html
http://kpasa.fnal.gov:8080/public/epsprime/epoe_intro.html
Technical Contact:
Prof. Edward Blucher, blucher@uchepa.uchicago.edu
Press Contact: Jeff
Sherwood, DOE Office of Public Affairs,
202-586-5806
SC-Funding Office:
Office of High Energy and Nuclear
Physics |