Deconfinement and degrees of freedom in $pp$ and $A-A$ collisions at LHC energies

TL;DR

This paper analyzes LHC collision data to extract temperature and degrees of freedom, revealing a two-step deconfinement process at around 210 MeV in both Pb-Pb and pp collisions, indicating a transition to quark-gluon plasma.

Contribution

It introduces a novel analysis of degrees of freedom in high-energy collisions, demonstrating deconfinement signatures in both lead-lead and proton-proton interactions using the CSPM model.

Findings

Identification of a two-step increase in degrees of freedom indicating deconfinement.

Observation of a sudden rise to ideal gas degrees of freedom at 210 MeV.

First evidence of deconfinement transition in pp collisions at LHC energies.

Abstract

We present the extraction of the temperature by analyzing the charged particle transverse momentum spectra in lead-lead (Pb-Pb) and proton-proton (${\bf pp}$) collisions at LHC energies from the ALICE Collaboration using the Color String Percolation Model (CSPM). From the measured energy density ${\bm \varepsilon}$ and the temperature T the dimensionless quantity ${\bm \varepsilon/}T^{4}$ is obtained to get the degrees of freedom (DOF), ${\bm \varepsilon}/T^{4}$ = DOF ${ \pi^{2}}$/30. We observe for the first time a two-step behavior in the increase of DOF, characteristic of deconfinement, above the hadronization temperature at temperature $\sim$ 210 MeV for both Pb-Pb and ${\bf pp}$ collisions and a sudden increase to the ideal gas value of $\sim $ 47 corresponding to three quark flavors in the case of Pb-Pb collisions.