Abstract
In framework of statistical models, different particle ratios at energies ranging from
3.5
to
200
GeV are calculated. Assuming that the particle production takes place along the freeze-out curve, we study the sharp peak in
K
+
/
π
+
ratio observed at SPS energy. We study the responsibility of non-equilibrium quark occupancy of phase space
γ
i
for particle production. Allowing
γ
i
to take values other than that of equilibrium, we got a very well description for
K
+
/
π
+
ratio at all energies. Using the resulting parameter set, we analyzed the
K
−
/
π
−
,
Λ/
π
+
and \hbox{
Λ/<π>
} ratios. We found that the corresponding peaks all are located at the same value of energy,
s
NN
−
−
−
−
√
(c)
≃7.5
GeV. At this energy, the entropy per particle is singular. The saddle-point in entropy per particle likely refers to critical phenomenon and change in the phase space.