Bose-Einstein correlations in perturbative QCD: Vn dependence on multiplicity

In this paper we study the dependence of Bose-Einstein correlations on the multiplicity of an event. We find that events with large multiplicity stem from the production of several-parton showers, while the additional production of small multiplicity in the central rapidity region (central diffraction) gives a negligible contribution due to emission of soft gluons, which leads to the Sudakov suppression of the exclusive production of two-gluon jets. Hence, the Bose-Einstein correlation is the main source of the azimuthal angle correlations which generate vn with odd and even n. We find that without this suppression, the measurement of an event with given multiplicity yields vn,n<0 for odd n. It appears that in hadron-nucleus and nucleus-nucleus collisions, the Bose-Einstein correlations do not depend on multiplicity, while for hadron-hadron scattering such dependence can be considerable. We propose a simple Kharzeev-Levin-Nardi type model to describe the dependence of azimuthal angle correlations on the centrality of the event in ion-ion collisions.