Jet Yields From Dihadron Correlations in PbPb Collisions at 2.76 TeV
Callner, Jeremy L.
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Measurements made using the CMS detector at the LHC of dihadron correlations of charged particles produced in PbPb collisions at nucleon-nucleon center-of-mass energy of 2.76 TeV are presented. The results are studied over a broad range of relative pseudorapity (∆η) and the full relative azimuthal angle (∆φ). The observed two-dimensional correlation structure in ∆η and ∆φ is characterized by a narrow peak at (∆η, ∆φ) ≈ (0,0) from jet-like correlations, which sits upon a long-range “ridge” structure that persists out to at least |∆η| = 4, and is assumed to be due to hydrodynamic flow. On the “away” side (|∆φ| ≈ π), the jet contribution is spread out quite evenly in ∆η and thus not easily distinguishable from the flow signal. The jet yields of both the near side and the away side are measured. The near-side jet yield is measured by directly subtracting off the ridge contribution. On the away side, where it is not so simple to separate the two, a new method for distinguishing the jet yield from the flow signal is presented along with its results.
SubjectLarge Hadron Collider