QCD phase-transition under the light of Thermofractal

TL;DR

This paper introduces a thermofractal framework to model the QCD deconfinement transition, transforming it from a sharp phase change into a smooth crossover by incorporating fractal momentum space structures, matching lattice data effectively.

Contribution

It develops a novel thermofractal approach that unifies the phase transition dynamics and reproduces lattice QCD results with high accuracy.

Findings

The phase transition is smoothed into a crossover via fractal momentum space.

A master equation for the Polyakov loop is derived, governed by the thermofractal index.

The model reproduces lattice QCD data with a reduced chi-squared of approximately 1.12.

Abstract

The deconfining transition in $SU(3)$ gauge theory, traditionally interpreted through the Gross-Witten-Wadia (GWW) model as a sharp third-order phase transition in the large-$N_c$ limit, appears as a smooth crossover in lattice QCD. This work demonstrates that the transition is topologically smoothed into a crossover by incorporating the fractal momentum space structure inherent to thermofractals. By matching the non-extensive $\beta$-function to one-loop QCD results, a fundamental scaling of the thermofractal index $q$ is derived as a function of the number of flavours $N_f$. It is proven that applying a $q$-deformed derivative operator $\mathcal{D}_q$ to the $q$-logarithm of the eigenvalue distance results in a non-extensive measure that effectively smears the topological stiffness of the gauge vacuum. A unified master equation for the Polyakov loop $\langle L \rangle$ is presented, governed by the thermofractal index $q$ and a single variance parameter $\sigma^2(T)$ that scales as $T^{1/(q-1)}$. The observed phase dynamics are shown to be asymptotic limits of this unified density: a ``soft'' algebraic growth $\langle L \rangle \propto T^{11}$ in the 1D string-like confined regime for $N_f=0$, and a rapid $1 - \langle L \rangle \propto T^{-21}$ suppression in the 3D deconfined volume for $N_f=3$. This approach provides a microscopic foundation for partial deconfinement theory and reproduces lattice QCD data with a reduced $\chi^2 \approx 1.12$, offering a rigorous reconciliation between matrix model topology and the continuous QCD crossover.