SLAC E158:  Measuring the Electron's WEAK Charge

Studying electron-electron Scattering in MIRROR WORLDS
to search for New Phenomena at the Energy Frontier

Polarized Electrons

Electrons, like visible light, can be polarized.  They have an intrinsic spin (angular momentum) which can be oriented parallel (right-handed polarization) or anti-parallel (left-handed polarization) to their momentum direction.  In a similar way that polaroid sunglasses transmit vertically-polarized light preferentially to horizontally-polarized light, the strength of the weak nuclear force (unlike the electromagnetic force or the strong nuclear force) is different for right-handed and left-handed particles.  Neutral Z particles and charged W⁺ and W^-  particles transmit the weak force (radioactivity is an example of a weak force interaction) and do so with different strengths for right-handed and left-handed particles.  The W⁺ and W^- interact only with left-handed particles, while the Z interacts with both but with different strengths.  This left-right asymmetry in weak interactions is known as parity violation. 

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