High transverse momentum triggered correlations over a large pseudorapidity acceptance in Au+Au collisions at sqrt(sNN)=200 GeV
Abstract
A measurement of two-particle correlations with a high transverse momentum trigger particle (pTtrig > 2.5 GeV/c) is presented for Au+Au collisions at sqrt(sNN) = 200 GeV over the uniquely broad longitudinal acceptance of the PHOBOS detector (-4 < η < 2). A broadening of the away-side azimuthal correlation compared to elementary collisions is observed at all η. As in p+p collisions, the near-side is characterized by a peak of correlated partners at small angle relative to the trigger particle. However, in central Au+Au collisions an additional correlation extended in η and known as the `ridge' is found to reach at least |η| ≈ 4. The ridge yield is largely independent of η over the measured range, and it decreases towards more peripheral collisions. For the chosen pTtrig cut, the ridge yield is consistent with zero for events with less than roughly 100 participating nucleons.