Abstract
Measurements of two-particle correlations on transverse momentum p t for Au-Au collisions at GeV are presented. Significant large-momentum-scale correlations are observed for charged primary hadrons with 0.15 ≤ pt ≤ 2 GeV/c and pseudorapidity |η| ≤ 1.3. Such correlations were not observed in a similar study at lower energy and are not predicted by theoretical collision models. Their direct relation to mean-p t fluctuations measured in the same angular acceptance is demonstrated. Positive correlations are observed for pairs of particles which have large pt values while negative correlations occur for pairs in which one particle has large pt and the other has much lower p t. The correlation amplitudes per final state particle increase with collision centrality. The observed correlations are consistent with a scenario in which the transverse momentum of hadrons associated with initial-stage semi-hard parton scattering is dissipated by the medium to lower pt.