Alternative Form of the Parity-Violating Current for the Hyperon Weak Radiative Decays and Hara Theorem

Abstract

It is shown that upon considering an alternative form of a parity-violating part of the transition electromagnetic current it is possible to reformulate Hara theorem in a way that it does not forbid any more nonzero asymmetry in the hyperon weak radiative decays ${\Sigma }^{+}\to p+\gamma$ and ${\Xi }^{-}\to {\Sigma }^{-}+\gamma$ in the limit of exact $SU(3{)}_f$ symmetry thus resolving a contradiction with the data and maybe revealing hitherto unseen transition toroid dipole moments. A result is consistent with the traditional one on the single-quark weak radiative transition models. We have also reproduced Vasanti formula at the quark level. As for two-quark weak radiative transitions we have found that the important part of it contains also a toroid dipole moment contribution which seems to be an intrinsic reason of the apparent contradiction between the Hara theorem conclusion and quark model results for hyperon weak radiative decays.

Comments: RevTex, 27 pages, submitted to Nucl. Phys. A