Azimuthal di-hadron correlations in d+ Au and Au + Au collisions at sqrt(s)NN=200 GeV measured at the STAR detector

Abstract

Yields, correlation shapes, and mean transverse momenta pT of charged particles associated with intermediate- to high-pT trigger particles (2.5<pT<10 GeV/c) in d+ Au and Au + Au collisions at √sNN=200 GeV are presented. For associated particles at higher pT≳2.5 GeV/c, narrow correlation peaks are seen in d+ Au and Au + Au, indicating that the main production mechanism is jet fragmentation. At lower associated particle pT<2 GeV/c, a large enhancement of the near- (Δϕ~0) and away-side (Δϕ~π) associated yields is found, together with a strong broadening of the away-side azimuthal distributions in Au + Au collisions compared to d+ Au measurements, suggesting that other particle production mechanisms play a role. This is further supported by the observed significant softening of the away-side associated particle yield distribution at Δϕ~π in central Au + Au collisions.