Subthreshold φ meson production in heavy-ion collisions

Within a BUU type transport model we study φ meson production in subthreshold Ni+Ni and Ru+Ru reactions. For the first time we included in our model the elementary reaction channels φ+N, Δ → φ+N, π+N(1520)Δ+N and πρ → φ. In spite of a substantial increase of the φ multiplicities by these channels our results stay significantly below the preliminary experimental data.