Influence of anisotropic $\Lambda /\Sigma$ creation on the ${\Xi }^{-}$ mutiplicity in subthreshold proton-nucleus collisions

Abstract

We present an analysis of ${\Xi }^{-}$ baryon production in subthreshold proton--nucleus ($p+A$) collisions in the framework of a BUU type transport model. We propose a new mechanism for $\Xi$ production in the collision of a secondary $\Lambda$ or $\Sigma$ hyperon and a nucleon from the target nucleus. We find that the ${\Xi }^{-}$ multiplicity in $p+A$ collisions is sensitive to the angular distribution of hyperon production in the primary $N+N$ collision. Using reasonable assumptions on the unknown elementary cross sections we are able to reproduce the ${\Xi }^{-}$ multiplicity and the ${\Xi }^{-}/(\Lambda +{\Sigma }^0)$ ratio obtained in the HADES experiment in $p$+Nb collisions at $\sqrt{s_{NN}}=$ 3.2 GeV energy.

Comments: 9 pages, 3 figures, final version accepted in Phys. Lett. B