Near-threshold production of the multi-strange ${\mathrm{\Xi }}^{-}$ hyperon

The yield for the multi-strange ${\mathrm{\Xi }}^{-}$ hyperon has been measured in 6 AGeV Au+Au collisions via reconstruction of its decay products ${\pi }^{-}$ and $\mathrm{\Lambda }$, the latter also being reconstructed from its daughter tracks of ${\pi }^{-}$ and p. The measurement is rather close to the threshold for ${\mathrm{\Xi }}^{-}$ production and therefore provides an important test of model predictions. The measured yield for ${\mathrm{\Xi }}^{-}$ and $\mathrm{\Lambda }$ are compared for several centralities. In central collisions the ${\mathrm{\Xi }}^{-}$ yield is found to be in excellent agreement with statistical and transport model predictions, suggesting that multi-strange hadron production approaches chemical equilibrium in high baryon density nuclear matter.