ABSTRACT
We have determined the quadratic slope parameter alpha for eta-->3pi(0) to be alpha = -0.031(4) from a 99% pure sample of 10(6)eta-->3pi(0) decays produced in the reaction pi(-)p-->n(eta) close to the eta threshold using the Crystal Ball detector at the AGS. The result is four times more precise than the present world data and disagrees with current chiral perturbation theory calculations by about four standard deviations.
ABSTRACT
We analyze the real-photon asymmetry A(gamma)(+/-) for the parity-violating (PV) pi(+/-) production on the Delta resonance via the reactions (-->)gamma + p --> Delta(+) --> pi(+) + n and (-->)gamma + d --> Delta(0) + p --> pi(-) + p + p. This asymmetry is nonvanishing due to a PV gamma N Delta coupling constant, d(Delta)(+/-). We argue that an experimental determination of this coupling would be of interest for hadron dynamics, possibly shedding light on the S-wave/ P-wave puzzle in the hyperon nonleptonic decays and the violation of Hara's theorem in weak radiative hyperon decays.
