Medium-modified evolution of multiparticle production in jets in heavy-ion collisions

The energy evolution of medium-modified average multiplicities and multiplicity fluctuations in quark and gluon jets produced in heavy-ion collisions is investigated from a toy QCD-inspired model. In this model, we use modified splitting functions accounting for medium-enhanced radiation of gluons by a fast parton which propagates through the quark-gluon plasma. The leading contribution of the standard production of soft hadrons is found to be enhanced by the factor root N-s while next-to-leading order (NLO) corrections are suppressed by 1/root N-s, where the nuclear parameter N-s > 1 accounts for the induced soft gluons in the hot medium. The role of next-to-next-to-leading order corrections (NNLO) is studied, and the large amount of medium-induced soft gluons are found to drastically affect the convergence of the perturbative series. Our results for such global observables are cross-checked and compared with their limits in the vacuum, and a new method for solving the second multiplicity correlator evolution equations is proposed.