From $K^+$ in heavy-ion collisions to $K^-$ in kaonic atoms
  Kaon production and kaon flow in heavy-ion collisions at SIS energies are analyzed using the relativistic transport model. The experimental data are found to be consistent with the scenario that kaon scalar (before being cut down by the range term) and vector mean field potentials are about 1/3 of that of nucleons in the Walecka model. This also explains the strong attraction found for $K^-$ in kaonic atoms, and gives information on the possibility of $K^-$ condensation in dense matter. 
G. E. Brown, C. M. Ko, and G. Q. Li