Deconfinement and degrees of freedom in $pp$ and $A-A$ 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 ($\mathbf{pp}$) collisions at LHC energies from the ALICE Collaboration using the Color String Percolation Model (CSPM). From the measured energy density $\mathbf{\epsilon }$ and the temperature T the dimensionless quantity $\mathbf{\epsilon }/T^4$ is obtained to get the degrees of freedom (DOF), $\mathbf{\epsilon }/T^4$ = 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 $\mathbf{pp}$ 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.

7 pages and 4 figures

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• The equation of state in (2+1)-flavor QCD
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• Percolation of color sources and critical temperature
• String Percolation and the Glasma
• Effective degrees of freedom and gluon condensation in the high temperature deconfined phase
• Ridge from Strings
• Percolation of Color Sources and the determination of the Equation of State of the Quark-Gluon Plasma (QGP) produced in central Au-Au collisions at \sqrt S_{NN}= 200 GeV
• Chiral phase structure of three flavor QCD in a background magnetic field
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• Investigating the soft and hard limits in transverse momentum spectra in pp collisions
• Jet Transport Coefficient at the Large Hadron Collider Energies in a Color String Percolation Approach
• Understanding the QCD medium by the diffusion of charm quarks using a Color String Percolation Model
• Multiplicity, transverse momentum and pseudorapidity dependence of open-heavy flavored hadron production in proton+proton collisions at $\sqrt{s}$= 13 TeV using PYTHIA8