Elsevier

Nuclear Physics A

Volume 528, Issues 3–4, 17–24 June 1991, Pages 557-588
Nuclear Physics A

Study from threshold to high momenta of the ppΛΛ reaction

https://doi.org/10.1016/0375-9474(91)90251-ZGet rights and content

Abstract

A semi-phenomenological model using the distorted-wave Born approximation method that incorporates the K-meson exchange is constructed for the ppΛΛ reaction. This diagram alone reproduces reasonably well all the available experimental data over a wide range of energies. This is mainly due to the strong annihilation in the distortions both in the initial and final states. The pp interaction is based on the Paris potential. The unknown ΛΛ interaction is built from the Paris potential and from the fit to the data. In order to achieve a good fit, a 2K-exchange box diagram and, at high momenta, a 2π exchange one, were added to the very short-range ΛΛ annihilation force. The explicit energy dependence in all our imaginary potentials is found to be crucial in the whole fit. As in results from similar models a rather strong P-wave contribution is found near threshold. In agreement with the spin-correlation measurements done so far, the strangeness production from pp annihilation is realized mainly in a ΛΛ triplet state. This can be attributed to the strong tensor force of the kaon exchange. The role of the K exchange is briefly discussed.

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    Unité de Recherche des Universités Paris 11 et Paris 6 Associée au CNRS.

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