Long-Range Pseudorapidity Correlations at High pT in sqrt(S_NN) = 200 GeV Au+Au Collisions with STAR
The Quark Gluon Plasma (QGP) is a form of matter in which quarks and gluons are deconfined, and was suggested to be formed in high-energy heavy-ion collisions. Since the discovery of high-pT hadron suppression in central Au+Au collisions at the Relativistic Heavy Ion Collider (RHIC), and the related discovery of the quenching of the away-side jet in these collisions, the role of jets as key probes of the QGP was re-affirmed. The Solenoidal Tracker At RHIC (STAR) detector system, which is suited for jet studies because of its large solid-angle coverage, has produced a number of interesting jet measurements in recent years, including gamma-jet measurements, attempts at full heavy-ion jet reconstruction, and two-dimensional correlations. A long-range correlation in pseudorapidity (the ?Ridge?) was studied (with statistical significance) out to pT^trig. <? 7 GeV /c and was assumed to have an integrated yield independent of pT^trig. Further studies out to higher pT were limited by the minimum biased statistics taken in Run 4 (2004) with STAR. This work presents results of a ridge analysis with (non-reconstructed) pi0s and direct-gamma-rich triggers out to ?13.5 GeV /c in pT^trig. Using triggered data from Run 7 (2007) and Run 10 (2010) Au+Au collisions detected with STAR. Preliminary results seem to indicate that the ridge yield decreases with pT^trig., and that the ridge yield for direct-?-rich triggers is consistent with zero.