Meson m T - scaling in heavy - ion collisions at SIS energies ∗

We perform systematical studies on transverse-mass spectra of π 0 , η, ω, φ, K + and K − mesons for C + C, Ni + Ni, Au + Au collisions at SIS energies within the HSD transport approach. We find that the m T-spectra sensitively reflect the in-medium properties of the mesons. The 'bare mass' scenario leads to a general scaling behaviour for the meson m T-spectra when including a mass shift due to the associate strangeness production threshold for kaons and antikaons whereas a 'dropping' mass scheme violates this m T-scaling. The relative slope parameters, however, provide valuable information about the average meson potentials in the nuclear medium.