We present the transverse momentum spectra and rapidity distributions of ${\pi }^{-}$ and ${\mathrm{K}}_S^0$ in Ar $+$ KCl reactions at a beam kinetic energy of $1.756$ $A$ GeV measured with the High Acceptance Di-Electron Spectrometer (HADES). The reconstructed ${\mathrm{K}}_S^0$ sample is characterized by good event statistics for a wide range in momentum and rapidity. We compare the experimental ${\pi }^{-}$ and ${\mathrm{K}}_S^0$ distributions to predictions by the Isospin Quantum Molecular Dynamics (IQMD) model. The model calculations show that ${\mathrm{K}}_S^0$ at low transverse momenta constitute a particularly well-suited tool to investigate the kaon in-medium potential. Our ${\mathrm{K}}_S^0$ data suggest a strong repulsive in-medium ${\mathrm{K}}^0$ potential of about 40 MeV strength.

• Received 22 April 2010

DOI:https://doi.org/10.1103/PhysRevC.82.044907