Authors
Abdallah, M. S. ; Aboona, B. E. ; Adam, J. ; Adamczyk, L.; Adams, J. R. ; Adkins, J.; Agakishiev, G.; Aggarwal, I.; Aggarwal, M.; Ahammed, Z; Aitbaev, A.; Spinka, H. M.; Underwood, D.G.; Zurek, M.
Abstract
Two-particle correlation measurements projected onto two-dimensional, transverse rapidity coordinates (yT 1, yT 2), allow access to dynamical properties of the QCD medium produced in relativisticheavy-ion collisions that angular correlation measurements are not sensitive to. We report nonidentified charged-particle correlations for Au + Au minimum-bias collisions at sNN = 200 GeVtaken by the STAR experiment at the Relativistic Heavy-Ion Collider (RHIC). Correlations arepresented as 2D functions of transverse rapidity for like-sign, unlike-sign and all charged-particlepairs, as well as for particle pairs whose relative azimuthal angles lie on the near-side, the away-side,or at all relative azimuth. The correlations are constructed using charged particles with transversemomentum pT 0.15 GeV/c, pseudorapidity from 1 to 1, and azimuthal angles from to . Thesignificant correlation structures that are observed evolve smoothly with collision centrality. Themajor correlation features include a saddle shape plus a broad peak with maximum near yT 3,corresponding to pT 1.5 GeV/c. The broad peak is observed in both like- and unlike-sign chargecombinations and in near- and away-side relative azimuthal angles. The all-charge, all-azimuthcorrelation measurements are compared with the theoretical predictions of hijing and epos. Theresults indicate that the correlations for peripheral to mid-central collisions can be approximatelydescribed as a superposition of nucleon + nucleon collisions with minimal effects from the QCDmedium. Strong medium effects are indicated in mid- to most-central collisions.