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


Abstract in English

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.

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