SLAC E158: Measuring the
Electron's WEAK Charge
|
||||||||||||
|
The Weak ForceWeak nuclear forces are responsible for radioactivity and also for exhibiting some peculiar symmetry features not seen with the other forces. In contrast to electromagnetic and strong forces, the strength of the weak force is different for particles and anti-particles (Charge Violation), for a scattering process and its mirror image (Parity Violation), and for a scattering process and the time reversal of that scattering process (Time Violation). The weak force drives radioactive decays that:
Some description and note of the significance of the weak interaction is
given in the following quote taken from the press release for the
1979 Nobel
Prize in Physics, awarded to Sheldon L. Glashow, Abdus Salam
and Steven Weinberg for their contributions to developing the
Standard
Model:
The strength of the weak force between
interacting quarks and leptons can be characterized by their weak
charge (distinct from their electric charge). The weak charges
of quarks and leptons are comparable to their electromagnetic charges, a manifestation of how
electromagnetism and the weak force are components of a unified
electroweak force. At “long”
distances approximately the width of a proton, the weak charge looks smaller
because of quantum fluctuations in the vacuum—every particle is surrounded
by an ephemeral cloud of particles that effectively form a screen between
interacting electrons. A primary purpose of the E158
experiment has been to establish the variation (running) of
the electron's weak charge with energy scale, or distance. The running
of interaction strengths (electric charges, weak and strong nuclear charges)
has previously been established for the electromagnetic and strong forces,
but not for the weak force. |
|||||||||||
Content Woods |
Last Update: 28 Jun 2005