On the influence of momentum conservation upon the scaling behaviour of factorial moments in high energy multiparticle production

Abstract

The experimental results on the falling down of scaled factorial moments in azimuthal variable is studied in some detail. It is shown that this phenomenon may be referred to the influence of transverse momentum conservation. The existing experimental data from DELPHI, EMU08, NA22 and UA1 are successfully explained. Various methods are proposed to partly eliminate this influence and rule out the 'falling down' of factorial moments.Since the last decade the anomalous scaling of scaled factorial moments (SFM's) or intermittency [1] has been studied extensively [2] with the aim of exploring the possible existence of dynamical fluctuation or multifractal structure of multiparticle spectrum in high energy collision processes. The corresponding experiments have been performed in various kind of collisions -from e>-e\, hadron-hadron, hadron-nucleus to nucleus-nucleus. Plenty of new and interesting experimental results have been put in front of us. Various efforts [3][4][5] have been taken to understand the physics behind these experimental findings.In this respect, it merits attention that, in almost all the cases, the logarithm of SFM's versus that of the cell width rises as the decreasing of (or as the increasing of partition number M of phase space, where M" / , is the total phase space region in consideration), when M is not very big. There is, however, a noticeable exception, i.e. the logarithm of SFM's with azimuthal angle as variable fall down as the increasing of lnM in the first few points [6-9], cf. Fig. 1. This prevents us from properly understanding the physics behind the scaling behaviour of SFM's found in experiments.The aim of this paper is to study this phenomenon in some detail. We will show that the falling down of SFM's in azimuthal angle may be referred to the influence of momentum conservation (MmCn) constraint in the collision processes. Various methods will be implemented to Fig. 1. Scaled factorial moments with azimuthal angle as variable, showing the 'falling down' phenomenon. Data taken from [6-9]