Event-by-event fluctuations in heavy-ion collisions and the quark-gluon string model

We apply dynamical string models of heavy-ion collisions at high energies to the analysis of event-by-event fluctuations. Attention is devoted mainly to a new variable proposed for studying ''equilibration'' in heavy-ion collisions. Recent results of the NA49 collaboration at CERN SPS are compared with predictions of the quark-gluon string model (QGSM), which gives a good description of different aspects of multiparticle production for collisions of nucleons and nuclei. It is shown that the new observable and other results of the NA49 analysis of event-by-event fluctuations are correctly reproduced in the model. We discuss dynamical effects responsible for these fluctuations and give the predictions for p-p, p-Pb and Pb-Pb collisions at RHIC and higher energies. (orig.)