Energy and System-size Dependence of Two-particle Azimuthal Correlations of High-pT Charged Hadrons at the CERN SPS

Angular correlations of high-pT hadrons can serve as a probe of interactions of partons with the dense medium produced in high-energy heavy-ion collisions but other sources of such correlations exist which can be non-negligible SPS energies. In an attempt to determine the primary source, NA49 has performed an energy and system-size scan of two-particle azimuthal correlations in central Pb+Pb, Si+Si and p + p collisions at 158A GeV, as well as central Pb + Pb collisions at 20A, 30A, 40A and 80A GeV. Moreover, results at 158A GeV have been compared to UrQMD simulations. PACS. 25.75.Bh Hard scattering in relativistic heavy ion collisions – 25.75.Gz Particle correlations and fluctuations – 25.75.Nq Quark deconfinement, quark-gluon plasma production and phase transitions in relativistic heavy-ion collisions