Semihard scattering unraveled from collective flow at the SPS
Revised: 10 May 2005
Published online: 8 July 2005
A study of elliptic flow and two-particle azimuthal correlations of charged particles ( GeV/c) and high- pions ( GeV/c) in Pb + Au collisions at 158A GeV/c, close to midrapidity, is presented. Elliptic flow (v 2) rises linearly with to a value of about 10 at 2 GeV/c. Beyond 1.5 GeV/c, the slope decreases and possibly indicates a v 2 saturation at high . Two-pion azimuthal anisotropies for 1.2 GeV/c exceed the v 2 values by about 60 in semicentral collisions. This non-flow component is attributed to near-side and away-side jetlike correlations. While the near-side peak remains constant with centrality 0.230.03 rad, as expected for fragmentation, the away-side peak experiences broadening and disappears in central collisions.
© Springer-Verlag, 2005