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Even though the natural length scale of string theory is much much much
much too small to be measured directly in particle experiments, there
are aspects of string theory that might be measurable with today's technology
or with technology of the near future.
One
of the predictions of string theory is that at higher energy scales we
should start to see evidence of a symmetry that gives every particle that
transmits a force (a boson) a partner particle that makes up matter (
a fermion), and vice versa.
This
symmetry between forces and matter is called supersymmetry.
The partner particles are called superpartners.
Known particles that transmit forces, and their possible
superpartners
| Name |
Spin |
Superpartner |
Spin |
| Graviton |
2 |
Gravitino |
3/2 |
| Photon |
1 |
Photino |
1/2 |
| Gluon |
1 |
Gluino |
1/2 |
| W+,- |
1 |
Wino+,- |
1/2 |
| Z0 |
1 |
Zino |
1/2 |
| Higgs |
0 |
Higgsino |
1/2 |
Known particles that make up matter, and their possible
superpartners
| Name |
Spin |
Superpartner |
Spin |
| Electron |
1/2 |
Selectron |
0 |
| Muon |
1/2 |
Smuon |
0 |
| Tau |
1/2 |
Stau |
0 |
| Neutrino |
1/2 |
Sneutrino |
0 |
| Quark |
1/2 |
Squark |
0 |
In
current particle experiments we can't yet see any direct evidence
for the existence of superpartners for known elementary particles (there
is some indirect evidence, however). There is a good chance we could start
to see superpartners in future particle experiments. If that happened,
it could turn out to be evidence for string theory. This could take place
in the next five or ten years, so come back to this web site for further
news. |
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