Wounded quarks in A+A, p+A, and p+p collisions

摘要

We explore predictions of the wounded quark model for particle production andproperties of the initial state formed in ultrarelativistic heavy-ioncollisions. The approach is applied uniformly to A+A collisions in a widecollision energy range, as well as for p+A and p+p collisions at the CERN LargeHadron Collider (LHC). We find that generically the predictions from woundedquarks for such features as eccentricities or initial sizes are close (within15\%) to predictions of the wounded nucleon model with an amended binarycomponent. A larger difference is found for the size in p+Pb system, where thewounded quark model yields a smaller (more compact) initial fireball than thestandard wounded nucleon model. The inclusion of subnucleonic degrees offreedom allows us to analyze p+p collisions in an analogous way, withpredictions that can be used in further collective evolution. The approximatelinear dependence of particle production in A+A collisions on the number ofwounded quarks, as found in previous studies, makes the approach based onwounded quarks natural. Importantly, at the LHC energies we find approximateuniformity in particle production from wounded quarks, where at a givencollision energy per nucleon pair similar production of initial entropy persource is needed to explain the particle production from p+p collisions up toA+A collisions. We also discuss the sensitivity of the wounded quark modelpredictions to distribution of quarks in nucleons, distribution of nucleons innuclei, and to the quark-quark inelasticity profile in the impact parameter. Inour procedure, the quark-quark inelasticity profile is chosen in such a waythat the experiment-based parametrization of the proton-proton inelasticityprofile is properly reproduced. The parameters of the overlaid multiplicitydistribution is fixed from p+p and p+Pb data.