Detection of Parity Nonconservation inΛDecay

Mirroring as an A Priori Symmetry

“…We follow Earman in considering the experiment of Crawford et al (1957). It was observed that when a negative pi meson, , scatters o¤ a proton, at certain energies it decays into two neutral particles (the hyperon, 0 , and the neutral K meson, K 0 ), de…ning a plane.…”

Handedness, parity violation, and the reality of space

“…Earman's example of a process that exemplifies such a law involves the decay of neutral hyperons that was experimentally investigated by Crawford et al (1957) as a test for parity violation. An example that may be more familiar is the β-decay of radioactive cobalt atoms, the subject of the first experimental confirmation of parity violation (Wu et al, 1957).…”

Consequences of Renormalizable Weak Interactions

“…5 is as follows: First it should be noted that this form is indeed equivalent to the derivative-type Yukawa interaction. It is known that this form of effective coupling is convenient 6,23 for explaining the observed angular distribution 1+a cos0 (a -0.5) of the A°-decay, 5 where 6 is the angle between the direction of the decay pion and the direction of the A 0 polarization (in the A 0 rest system). For the Yukawa-type direct (renormalizable) interaction p(l+ry 5 )Ao<p7r+H.c., r must be as large as 10 in order to get such a large asymmetry factor.…”

“…4 Moreover, if we assume that the parity violation in the hyperon decays occurs through its extremum form, 1±75, which preserves the time-reflection invariance, the unrenormalizable derivative-type Yukawa interaction is favored by experiments as the effective A°-decay coupling, since it predicts the angular distribution of the pion produced in the polarized A°-decay consistent with recent experiments. 5 Under these significant circumstances, two distinct points of view may be conceivable. One is to accept this unrenormalizability as a fundamental feature 6 of the weak interactions; the other is, assuming that all basic primary interactions should have renormalizable forms, to speculate that all phenomenological weak reactions are caused by some unknown intermediary bosons.…”