Parity violation in electron-nucleus scattering

Breaking these up into transitions involving left-handed or right-handed particles, using the 9 dependence discussed in Section 8.5, and keeping only the dominant terms for M, one gets [with C = (2 sin 6w cos 

In the last step the probability functions for finding quark j, being independent of j for an isoscalar target, have cancelled out. 

In the denominator we can ignore the contribution completely. In the numerator we keep just the dominant j — interference terms and 

An experiment of extraordinary delicacy has been carried out at SLAG (Prescott et ai, 1978). The polarized electrons are produced by optical pumping of a gallium arsenide crystal using circularly polarized photons, and a mean electron polarization of 0.37 is obtained. The measured asymmetry is 

The variation of Aexp as the beam polarization is varied from positive through zero to negative values. 

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