Complete set of polarization observables inp→p→→ppπ0close to threshold

Abstract

In a kinematically complete experiment we have measured the two analyzing powers and the five spin correlation coefficients of the reaction $\stackrel{\ensuremath{\rightarrow}}{p}\stackrel{\ensuremath{\rightarrow}}{p}\ensuremath{\rightarrow}\mathrm{pp}{\ensuremath{\pi}}^{0}$ as a function of all five parameters of the three-body final state for bombarding energies between 325 and 400 MeV. The data are in disagreement with the theoretical predictions available at this time. Below 400 MeV, fewer than a dozen complex partial-wave amplitudes are likely to be significant, and it is expected that the present experimental information constrains these amplitudes. We also describe the formalism for an expansion of the spin observables into a complete set of angular functions and use this to completely characterize the polarization information obtainable from reactions with polarized spin-1/2 collision partners and a three-body final state.