Circular Polarization of Gamma Rays and Parity Nonconserving Interactions

weak interaction theories en vogue. Effects of short range correlations (SRC) have been taken into account as exactly as possible3-4. The results (due to admixtures only) obtained for various strong and weak N-N-potentials are far away from agreement with most other calculations done up to now (see Refs. quoted in 4 ). No weak interaction theory seems to be able to explain the experimental values. At this point one should remind that diagram Fig.la gives no contribution in exact SU(2) (in taking into account isospin-breaking only with a negligible amplitude5 concerning the strangeness conserving currents). So the only contribution entering with the cos20 factor is due to ^-exchange and therefore is highly affected by short range correlations. Recently we found, however, that calculations of irregular transitions through parity mixing (PNC) are not gauge-invariant6. Gauge invariance requires that processes of direct photo emission (PNE), such as Fig. (2a and b) (and additional) also must be included. These processes were shown (in contrast to process Fig. la) not to vanish, even in exact SU(2), which means that the one 7z-exchange contribution can enter with the cos2 6 factor in the