Abstract

BAUTISTA, I.; PAJARES, C.  and  RAMIREZ, J.E.. String percolation in AA and p+p collisions. Rev. mex. fis. [online]. 2019, vol.65, n.3, pp.197-223.  Epub Apr 30, 2020. ISSN 0035-001X.  https://doi.org/10.31349/revmexfis.65.197.

A brief review of the string percolation model and its results are presented together with the comparison to experimental data. First, an introduction to the quark-gluon phase diagram and the lattice results concerning the confinement and the percolation center domains is done. The interaction of the strings produced in nucleus-nucleus and proton-proton collisions is studied, showing how the string percolation arises. The main consequences of the string percolation, concerning the dependence on the energy and centrality, on the multiplicities and the mean transverse momentum, are obtained comparing with experimental data. the non-abelian character of the color field of the strings forming the cluster is emphasized to reproduce the rise of the transverse momentum with multiplicity and the relative suppression of multiplicities. It is also studied different observables like multiplicity and transverse momentum distributions, dependence with multiplicity and transverse momentum correlations, forward-backward correlations, the strength of the Bose-Einstein correlations, dependence on the multiplicity of J/Ψ production and its possible suppression in p+p collisions at high multiplicity, strangeness enhancement, elliptic flow, and ridge structure are also studied. The comparison with the data shows an overall agreement. The thermodynamical properties of the extended cluster formed in the collision are discussed computing its energy and entropy density, shear viscosity over entropy density ratio, bulk viscosity, sound speed and trace anomaly as a function of temperature, showing a remarkable agreement with lattice QCD evaluations. The string percolation can be regarded as the initial frame able to describe the collective behavior produced in AA and p+p collisions.

Keywords : Strings; percolation; QCD; high density matter; confinement; heavy ion collisions; proton-proton collisions.

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