Non-thermal phase transition in $pp$ collisions at 400 GeV/c

The pseudorapidity distribution for charged particles produced in pp collisions at 400 GeV/c has been measured by using the LEBC films offered by the CERN NA27 collaboration. The factorial moments up to q =7 have been calculated by star integral method. The analytic results indicate that a non-thermal phase transition and two different regimes of multiparticle production may exist. The multifractal structure of the fluctuation has been observed supporting the random cascade model of particle production. (10 refs).