We suggest using net-baryon rapidity distributions in central relativistic heavy-ion collisions at energies reached at the CERN Super Proton Synchrotron, BNL Relativistic Heavy-Ion Collider (RHIC), and CERN LHC in order to probe saturation physics. Within the color glass condensate framework based on small-coupling QCD, net-baryon rapidity distributions are shown to exhibit geometric scaling. In a comparison with RHIC data in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{NN}}=62.4\mathrm{GeV}$ and 200 GeV the gradual approach to the gluon saturation regime is investigated. Predictions for net-baryon rapidity spectra and the mean rapidity loss in central $\mathrm{Pb}+\mathrm{Pb}$ collisions at LHC energies of $\sqrt{s_{NN}}=5.52\mathrm{TeV}$ are made.

• Received 24 September 2008

DOI:https://doi.org/10.1103/PhysRevLett.102.182301