On the Dynamical Fluctuations in the Multiparticle Final States of e⁺ e^- Collisions

Abstract：

The scaling property of factorial moments in the mulhpanicle final-states of e⁺e^－ collisions is studied in both the laboratory and the thrust-axis coordinate systems by using the Jetset generator. It turns out that in both of the two cases, the 3-dimensional InF²～InM are approximately stndght lines when the phase space are divided isotropically in different direchons, showing that the dynamical fluctuations in the multiparticle final-state of e⁺e^－ collisions are approximately isotropic. In the lab system, the three γ parameters obtained by fitting F₂～M of p_x, p_y, p_z to Ochs formula respechvely are approximately equal. In the thrust system, the three γ values obtained by fitting F₂(y)～M,F₂(p_t)～M and F₂(φ)～M are also close to each other provided the starting point in fining F₂(φ)～M is chosen appropriately. All of these provide further evidence for the above assertion. Our resultS show that the essential feature, i.e. anisotropy of (approximate) isotropy, of the dynamical fluctuations in soft and hard processes can be revealed by studying the scaling property of factorial moments in the collisions. Therefore, further inveshgation of the scaling properties of factorial moments in various kinds of collision processes is significant for the understanding of the essenhal charetarishcs of collision dynamics.