Soft and hard scales of the transverse momentum distribution in the Color String Percolation Model

TL;DR

This paper models the transverse momentum distribution in the color string percolation framework using a q-Gaussian distribution, linking the distribution's parameters to collision energy and centrality, and identifying conditions for quark-gluon plasma formation.

Contribution

It introduces a comprehensive description of the TMD in the color string percolation model by incorporating q-Gaussian fluctuations and analyzing their dependence on collision parameters.

Findings

q-Gaussian parameters increase with collision energy and centrality.

The model reproduces low and high p_T scales effectively.

A phase diagram indicates conditions for quark-gluon plasma formation.

Abstract

In color string models, the transverse momentum distribution (TMD) is obtained through the convolution of the Schwinger mechanism with the string tension fluctuations distribution. Considering a $q$-Gaussian distribution for these fluctuations, the TMD becomes a hypergeometric confluent function that adequately reproduces the characteristic scales at low and high $p_T$ values. In this approach, the hard scale of the TMD is a consequence of considering a heavy-tailed distribution for the string tension fluctuations whose width rises as $\sqrt{s}$, multiplicity or centrality increases. In this paper, we introduce the complete information of the TMD in the color string percolation model by means of the determination of the color suppression factor, which now also depends on the parameters of the $q$-Gaussian. To this end, we analyze the reported data on pp and AA collisions at different center of mass energies, multiplicities, and centralities. In particular, for minimum bias pp collisions, we found that the $q$-Gaussian parameters and the effective temperature are monotonically increasing functions of the center of mass energy. Similar results are found for AA collisions as a function of the centrality at fixed $\sqrt{s}$. We summarize these results in a phase diagram that indicates the $q$-Gaussian parameters region allowing the quark-gluon plasma formation.