Disoriented Chiral Condensate and Charge-Neutral Particle Fluctuations in Heavy Ion Collisions

The posibility of large charge and isospin fluctuations in high-energy heavy ion-collisions is studied within the framework of the nonlinear $\sigma $-model with quark degrees of freedom. The multipion exchange potential between two quarks is derived. It is shown that the soft chiral pion bremsstralung leads to anomalously large fluctuations in the ratio of neutral to charged pions, predicted by the formation of a disoriented chiral condensate (DCC). The factorization property of the scattering amplitude in the impact parameter space of the leading two-nucleon system is used to study semiclassical production of pions in the central region. We show that the DCC-type fluctuations are suppressed if a large number of pions are produced in $\rho $-type clusters. Our conclusion is supported through the calculation of two pion correlation parameters as a function of the $\rho $-to-$\pi $ ratio.