Canonical Strangeness and Distillation Effects in Hadron Production

Strangeness canonical ensemble for Maxwell-Boltzmann statistics is reconsidered for excited nuclear systems with non-vanishing net strangeness. A new recurrence relation method is applied to find the partition function. The method is first generalized to the case of quantum strangeness canonical ensemble. Uncertainties in calculation of the K+/pi+ excitation function are discussed. A new scenario based on the strangeness distillation effect is put forward for a possible explanation of anomalous strangeness production observed at the bombarding energy near 30 AGeV. The peaked maximum in the K+/pi+ ratio is considered as a sign of the critical end-point reached in evolution of the system rather than a latent heat jump emerging from the onset of the first order deconfinement phase transition.