Nucleus–nucleus collisions at high baryon densities

Nucleus - nucleus collisions at high baryon densities

We study central collision of P b + P b at 20, 40, 80 and 160 A·GeV within the UrQMD transport approach and compare rapidity distributions of π − , K + , K − and Λ with the recent measurements from the NA49 Collaboration at 40, 80 and 160 A·GeV. It is found that the UrQMD model reasonably describes the data, however, systematically overpredicts the π − yield by ∼ 20%, whereas the K + yield is u...

Estimating ŋ/s of QCD matter at high baryon densities

We report on the application of a cascade + viscous hydro + cascade model for heavy ion collisions in the RHIC Beam Energy Scan range, √ sNN = 6.3 . . . 200 GeV. By constraining model parameters to reproduce the data we find that the effective (average) value of the shear viscosity over entropy density ratio η/s decreases from 0.2 to 0.08 when collision energy grows from √ sNN ≈ 7 to 39 GeV.

Recent lattice QCD results at non-zero baryon densities

Baryon - to - Entropy Ratio in Very High Energy Nuclear Collisions

We compute as a function of rapidity y the baryon number carried by quarks and antiquarks with pT > p0 ≈ 2 GeV produced in Pb+Pb collisions at TeV energies. The computation is carried out in lowest order QCD perturbation theory using structure functions compatible with HERA results. At p0 = 2 GeV the initial gluon density is both transversally saturated and thermalised in the sense that the ene...

Baryon Number Transport in High Energy Nuclear Collisions

Abstract: Recent SPS data on the rapidity distribution of protons in p+S, p+Au and S+S collisions at 200 AGeV and preliminary Pb+Pb collisions at 160 AGeV are compared to HIJING and VENUS calculations as well as to predictions based on the Multi-Chain Model (MCM). The preliminary Pb data suggest that a linear dependence of the proton rapidity shift as a function of the nuclear thickness, as fir...