Electroweak Analogue of the Stern-Gerlach Effect: Parity Conservation Restored?

The history of the longitudinal polarization experiments carried out by Wu et al, in 1957 is reviewed. It is pointed out that the conclusion that these results are an indication of parity non-conservation in weak decays rests on a key assumption, namely that the electron and neutrino are created in the decay and are not present in the nucleus beforehand. Calculations employing the exponentially damped Breit-Pauli Hamiltonian have shown that is possible to bind an electron in the neutron strongly enough to overcome the high kinetic energy required to keep it in the small volume of the nucleus, contrary to the widespread belief to the contrary promulgated by Fermi and co-workers. On the basis of the combined electroweak interaction, it is reasonable to expect that something akin to the magnetic Stern-Gerlach effect might be operative in such decay processes. In this case, in-homogenous fields can be expected to have a dominant effect on the spins of the decay particles. The field gradient should be positive, i.e. increasing in the direction of the field, at the onset of the decay for the lightest particles and therefore determine whether the momentum of the antineutrino is parallel or antiparallel to its spin. Based on this assumption, one arrives in a straightforward way at the conclusion that anti-neutrinos will always behave as right-handed screws in weak decays and neutrinos as left-handed screws. Similar effects are expected for positrons and electrons, respectively, but only with partial polarization governed by their v/c ratios in the decays. Other heavier particles such as the proton and muon simply react to the motion of the lighter particles so as to satisfy the conservation laws of energy and linear and angular momentum. The resulting dynamical 
interpretation of the weak decays thus avoids the conclusion that parity is not conserved in all interactions.


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