|
SLD
Event Display of a Z particle
decaying to two quarks. An electron
and positron travelling in opposite
directions (perpendicular to this
page) collided at the center of
the detector and annihilated,
creating a Z. The Z subsequently
decayed to a quark and anti-quark,
which then hadronized to form
two jets of particles traveling
in opposite directions. These
are the two jets of green tracks
seen in this projection. |
Research supported by the Office
of Science is making progress in the
intense search for the Higgs boson,
which may be the force that finally
explains why some fundamental particles
have mass, but others do not. Higgs
is the last undiscovered component
of the Standard Model, physicists'
current theory of matter and the forces
of nature. The model includes three
families of particles called quarks
and leptons; bosons carry forces between
other particles. The Standard Model
predicts a relationship between the
masses of the Higgs boson, the W boson
(which carries the "weak force"),
and a particle called the top quark.
Precise measurements of the properties
of the top quark and W boson at Fermi
National Accelerator Laboratory and
the Zo at the Stanford Linear Accelerator
Center in the 1990s significantly
narrowed the predicted range for the
mass of the Higgs boson. The SLAC
experiments obtained what remains
the most precise prediction of the
mass of the Higgs, hinting that it
should be light.
Scientific Impact:
These experiments told scientists
what mass range to seek in direct
measurements of the Higgs boson; when
the Higgs is found, comparisons of
direct and indirect measurements will
provide a strong test of the Standard
Model. The results also suggest that
the Higgs might be within reach of
existing accelerators.
Social Impact: Research
on subatomic particles answers 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: "Improved
Direct Measurement of Leptonic Couplings
Asymmetries with Polarized Z Bosons,"
K. Abe et al. (The SLD Collaboration),
Phys. Rev. Lett. 86, 1162,
(2001).
URL:
http://www-sldnt.slac.stanford.edu/alr/
Technical Contact:
Dr. Martin Breidenbach, mib@slac.stanford.edu
Press Contact: Jeff
Sherwood, DOE Office of Public Affairs,
202-586-5806
SC-Funding Office:
Office of High Energy and Nuclear
Physics |