Strangeness enhancement scenarios: Fireball or independent strings?

Due to the long-standing discrepancy between NA35 and NA36 data on Λ production two drastically different scenarios of strangeness enhancement are still possible. Independent string models, such as the dual parton model, lead to results close to the NA36 data. On the contrary, the NA35 results can only be described by introducing full final state rescattering of the produced particles. The corresponding predictions for central PbPb collisions at CERN energies differ by a factor 3 to 4. Preliminary data on the net proton (p-p) rapidity distribution in PbPb collisions favor the independent string scenario.