engleski

The importance of the nucleon-nucleon correlations for the eta-alpha S-wave scattering length, and the pi0-eta mixing angle in the low-energy eta-alpha scattering length model

Using the new set of dd-->eta alpha near- threshold experimental data, the estimate of the importance of the nucleon-nucleon correlations for the eta-alpha S-wave scattering length in the multiple scattering theory is obtained using the low-energy scattering length model. The contribution turns out to be much bigger then previously believed. Th epi0-eta mixing angle is extracted using the experimental data on the dd-->eta alpha and dd- ->pi0 alpha processes. The model is dominated by the subthreshold extrapolation recipe for the eta-alpha scattering amplitudes. When the recipe is chosen, the model is completely insensitive to the eta-alpha parameters for the subthreshold value of the eta cm momentum p(eta)2= -(0.46)fm-2. Provided that the subthreshold extrapolation is correct, a good estimate of the pi0-eta mixing angle is obtained if the experimental cross sections for the dd-->pi0 alpha reaction at the corresponding deuteron input energy is taken from the literature.

eta-alpha scattering length; pi0-eta mixing angle

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