Deep sub-threshold $\hat{I}{ž}^{-}$ production in Ar+KCl reactions at 1.76A GeV

Abstract

We report first results on a deep sub-threshold production of the doubly strange hyperon $\hat{I}{ž}^{-}$ in a heavy-ion reaction. At a beam energy of 1.76A GeV the reaction Ar+KCl was studied with the High Acceptance Di-Electron Spectrometer (HADES) at SIS18/GSI. A high-statistics and high-purity $\hat{I}›$ sample was collected, allowing for the investigation of the decay channel $\hat{I}{ž}^{-}\to \hat{I}›\ddot{I}{€}^{-}$. The deduced $\hat{I}{ž}^{-}/(\hat{I}›+\hat{I}{\pounds }^0)$ production ratio of $(5.6\pm 1.2_{-1.7}^{+1.8})\cdot 10^{-3}$ is significantly larger than available model predictions.

4 pages, including 4 figures