Canonical strangeness and distillation effects in hadron production

The 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 the calculation of the K+/π+ 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 ~30 GeV. The peaked maximum in the K+/π+ ratio is considered as a sign of the critical endpoint reached in evolution of the system rather than a latent heat jump emerging from the onset of the first-order deconfinement phase transition.