Selected Citation

Chirality Invariance and the Universal Fermi Interaction

Authors(s):E. C. G. Sudarshan and R. E. Marshak Publication:Physical Review Publication Date:March 1, 1958 Publisher: American Physical Society Citation:PhysRev.109.1860.2 Link:

WE have shown' that the imposition of the requirement of chirality invariance' on each covariant in the four-fermion interaction Hamiltonian leads to the essentially unique expression': [equation] where G is the coupling constant and A, 8, C, D are four Dirac particie fields. In the standard terminology of parity-conserving interactions, (I) represents the combination V — A (V is vector, A is axial vector). We assumed that (I) holds between any two of the pairs' nP, AP, p i, e R (i. e. , the Particles are taken to be the neutron, proton, A hyperon, negative muon, neutrino, and electron) with the same value of G. Such a universal V — four-fermion interaction is invariant under A "combined inversion, yields a two-component neutrino of negative helicity, leads to conservation of leptons, and gives the maximal violation of parityapart from conserving chirality.

In comparing the predictions of the V—A theory with experiment, we pointed out at the Padua-Venice Conference that the theory could explain all beta-decay experiments (allowed as well as forbidden, parity-conserving as well as parity-nonconserving) except the electron-neutrino correlation in He and the electron asymmetry from polarized neutron decay, all the muon experiments except the very preliminary experiment at Columbia' on the positron polarization from pion decay, the decay of the pion except for the apparent absence of the electron mode, and all existing results on strange particle decays. Since the conference, the validity of the He6 experiment has been questioned*, the polarized neutron experiment has come down to a value consistent with the V—A theory and the helicity of the poster from the pion decay has turned out to be +1, as it should. There has been no change in the experimental situation with regard to the electron decay of the pion but it is clear that this very difficult experiment should be redone. * C.S. Wu (private communication); the experiment must be redone.