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Short- and long-range very-high-pT triggered dihadron correlations in PbPb collisions at 2.76 TeV with CMS

Aug 14, 2012, 3:15 PM


Oral Presentation Correlations and fluctuations Parallel 1C: Correlations & Fluctuations (Chair J. Schukraft)


Rylan Towne Conway (University of California Davis (US))


New precision measurements of dihadron correlations triggered by a very high-pT particle in 2.76 TeV PbPb collisions over a broad range of pseudorapidity and the full range of azimuthal angle will be presented. Utilizing a novel and unique high-pT single-track high-level trigger, the analysis explores the full 2011 PbPb data set corresponding to an integrated luminosity of 150/ub collected by CMS. For the first time, a long-range correlation structure up to |delta-eta|~4 at small delta-phi (near side) is observed for such very high-pT (e.g., pT~20 GeV/c) trigger particles correlated with low-pT (a few GeV/c) associated particles. The observed long-range correlations in |delta-eta| on the near side are consistent with the single-particle azimuthal anisotropy (characterized by the Fourier harmonics, vn) of high-pT trigger particles measured relative to the event-plane angle determined with the forward hadronic calorimeters. After subtracting the vn harmonics component, the shape and yield on the near (|delta-phi| < 1) and away (|delta-phi| > 1) side of the residual dihadron correlations have been studied systematically over a wide kinematic range in trigger (12 < pT[trig] < 50 GeV/c) and associated ( 0.5 GeV/c < pT[assoc] < pT[trig]) particle pT, as a function of pseudorapidity and collision centrality. The results are compared to those in pp collisions at the same energy.

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