Speaker
Description
author: Mikhail Tokarev
co-author: Imrich Zborovsky
Mikhail Tokarev$^{1 \natural}$ and Imrich Zborovsky$^{2 \flat}$
$^1$Joint Institute for Nuclear Research, Dubna, Russian
$^2$The Czech Academy of Science, Nuclear Physics Institute, Rez, Czech Republic
$^{\natural}$ E-mail: tokarev@jinr.ru
$^{\flat}$ E-mail: imrichzborovsky@gmail.com
Selection of cumulative events is assumed to enrich data samples by a new type of collisions characterized by higher energy density and more compressed matter. We expect that this will allow finding clearer signatures of phase transition, location of a critical point and studying extreme conditions in heavy ion collisions. The concept of $z$-scaling based on the principles of self-similarity, locality and fractality reflecting general features of particle interactions is reviewed. The concept was used to describe of high-$p_T$ particle production in cumulative and non-cumulative regions. The self-similarity variable $z$ is a function of the momentum fractions $x_1$ and~$x_2$ of the colliding objects carried by interacting hadron constituents and depends on the fractions $y_a$ and $y_b$ of the scattered and recoil constituents carried by the inclusive particle and its recoil counterpart. The scaling function $\psi(z)$ is expressed via inclusive cross-section, multiplicity density and three model parameters. Structure of the colliding objects and fragmentation processes is characterized by the structural and fragmentation fractal dimensions $\delta$ and $\epsilon$, respectively. The produced medium is described by a "specific heat" $c$. The change in parameters of the theory (a specific heat and fractal dimensions) near the critical point is considered as a signature of new physics. The results of data analysis of cumulative production in p+A and A+A collisions in collider and fixed target mode are discussed.
