Search

We calculate the inclusive spectra of secondaries produced in soft (minimum bias) p+Pb collisions in the framework of Quark-Gluon String Model at LHC energy, and by taking into account the inelastic screening corrections (percolation effects). The role of these effects is expected to be very large at very high energies, and they should decrease the spectra more than 1.5 times in the midrapidity region and increase them about 1.5 times in the fragmentation region at the energy of LHC. [ABSTRACT FROM AUTHOR]

We discuss the dependence of J/ψ production on the charged particle multiplicity in proton-proton collisions at CERN Large Hadron Collider (LHC) energies. We show that, in the framework of parton saturation or string interaction models, the hard J/ψ production exhibits a significant growth with the multiplicity, which is stronger than linear in the high density domain. This departure from linearity, that should affect any hard observable, applies for high multiplicity proton-proton collisions in the central rapidity region and is a consequence of the parton saturation or the strong interaction among color ropes that take place at LHC energies. Our assumption, the existence of coherence effects present in proton-proton collisions at high energy, can also be checked by studying the particular shape of the probability distribution associated to the J/ψ production. Predictions for the forthcoming pPb collisions at LHC energies are presented. [ABSTRACT FROM AUTHOR]

We present our results on the shear viscosity to entropy ratio ( η/ s) in the framework of the clustering of the color sources of the matter produced at RHIC and LHC energies. The onset of de-confinement transition is identified by the spanning percolating cluster in 2D percolation. The relativistic kinetic theory relation for η/ s is evaluated using the initial temperature ( T) and the mean free path ( λ). The analytic expression for η/ s covers a wide temperature range. At T∼150 MeV below the hadron to QGP transition temperature of ∼168 MeV, with increasing temperatures the η/ s value drop sharply and reaches a broad minimum η/ s∼0.20 at T∼175-185 MeV. Above this temperature η/ s grows slowly. The measured values of η/ s are 0.204±0.020 and 0.262±0.026 at the initial temperature of 193.6±3 MeV from central Au+Au collisions at $\sqrt{s_{NN}}=200~\mathrm{GeV}$ (RHIC) and 262.2±13 MeV in central Pb+Pb collisions at $\sqrt{s_{NN}} = 2.76~\mathrm{TeV}$ (LHC). These η/ s values are 2.5 and 3.3 times the AdS/CFT conjectured lower bound 1/4 π but are consistent with theoretical η/ s estimates for a strongly coupled QGP. [ABSTRACT FROM AUTHOR]

Abstract: We argue that string percolation is in the origin of (i) an approximately flat rapidity distribution and of (ii) an approximately constant forward-backward correlation parameter b over a substantial fraction of the available rapidity. Predictions are given for pp collisions at LHC, and . [Copyright &y& Elsevier]