Speaker
Description
The concepts of "scaling" and "universality" have been developed to study critical phenomena. Scaling implies that systems near a critical point (CP) exhibit self-similarity and are invariant with respect to scale transformations. The universality of their behavior lies in the fact that vastly different systems behave in a similar way near the respective CP.
We present some results of analysis of hadron production in $p+p$ and $A+A$ collisions obtained in the framework of $z$-scaling in searching for signatures of a phase transition in nuclear matter. This approach is one of the methods allowing systematic analysis of experimental data on inclusive cross sections over a wide range of the collision energies, multiplicity densities, transverse momenta, and angles of various particles. The concept of the $z$-scaling is based on the principles of self-similarity, locality and fractality reflecting general features of particle interactions. 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 function $\psi(z)$ reveals energy, multiplicity, angular and flavor independence found in analyses of inclusive spectra measured at the ISR, SPS, Tevatron, RHIC and LHC. A microscopic scenario of hadron production in terms of constituent momentum fractions and recoil mass of produced system is developed. The constituent energy loss as a function of energy and centrality of collision and transverse momentum of inclusive particle is estimated in the $z$-scaling approach. Discontinuity of the model parameters - the fractal and fragmentation dimensions and "heat capacity" - are discussed from the point of view of the search for a phase transitions in the nuclear matter.
- M. Tokarev, A. Kechechyan, I. Zborovsky, Nucl. Phys. A 993, 121646 (2020).
- M. Tokarev et al., Phys. Part. Nucl. 51, 141 (2020).
- I. Zborovsky, Int. J. Mod. Phys. A 33, 1850057 (2018).
- M. Tokarev, I. Zborovsky, Int. J. Mod. Phys. A 32, 1750029 (2017).
- I. Zborovsky, M. Tokarev, Phys. Part. Nucl. Lett. 18, 302 (2021).
