Sub-threshold production of $\mathrm{\Sigma }$(1385) baryons in Al+Al collisions at 1.9$A$ GeV

First measurement of sub-threshold $\mathrm{\Sigma }$(1385) production is presented. Experimental data are presented for Al+Al reactions at 1.9$A$ GeV measured with the FOPI detector at SIS/GSI. The $\mathrm{\Sigma }$(1385)/$\mathrm{\Lambda }$ ratio is found to be in good agreement with the transport and statistical model predictions. The results allow for a better understanding of sub-threshold strangeness production and strangeness exchange reaction which is the dominant process for $K^{-}$ production below and close-to threshold.