Double strangeness production in (p)over-barXe annihilation at low energy

The final results of the search of double strangeness final states, i.e. th e production of two strange quarks and two antistrange quarks, the latter c arried by the produced strange hadrons, from the analysis of a sample of 7. 8 . 10(5) low energy (P less than or equal to 0.9 GeV/c) antiproton annihil ations on Xenon nuclei, are presented. An overall number of 33 double stran geness events were found and are discussed. The corresponding yields are al l at the level of 10(-4), a value unexpectedly high with respect a naive ex pectation based on measurements of simple strangeness production on a free nucleon. However, conventional processes in nuclear matter described by the intranuclear cascade models seem to be able to explain this apparent stran geness enhancement. Two mechanisms play a special role, as checked also by a Monte Carlo calculation: the (p) over bar N --> K (K) over bar omega reac tion, followed by the associated strangeness production omega N --> KY, and the Xi-formation process, followed by Xi N --> Lambda Lambda. (C) 1999 Pub lished by Elsevier Science B.V. All rights reserved.