Critical surfaces in the phase space of particles produced inclusively in hadron-hadron collisions

The recently reported discovery (L. N. Abesalishvili, et al., JETP Lett. 30, 419 (1979)) of critical surfaces in the phase space of positive pions produced inclusively in ..pi../sup -/p interactions at 40 GeV/c is discussed. It is shown that the appearance of this surface is a fortuitous fact associated with the small pion mass and the small mean transverse momentum of the produced pions. (AIP)