STAR measurements of dihadron azimuthal correlations (Δϕ) are reported in midcentral (20–60%) Au + Au collisions at √sNN = 200 GeV as a function of the trigger particle's azimuthal angle relative to the event plane, ϕs = |ϕt ψEP |. The elliptic (v2), triangular (v3), and quadratic (v4) flow harmonic backgrounds are subtracted using the zero yield at minimum (ZYAM) method. The results are compared to minimum-bias d + Au collisions. It is found that a finite near-side (|Δϕ| < π/2) long-range pseudorapidity correlation (ridge) is present in the in-plane direction (ϕs∼0). The away-side (|Δϕ| > π/2) correlation shows a modification from d + Au data, varying with ϕs. The modification may be a consequence of path-length-dependent jet quenching and may lead to a better understanding of high-density QCD.

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Published in Physical Review C: Nuclear Physics, v. 89, article 041901(R), p. 1-7.

©2014 American Physical Society

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Due to the large number of authors involved, only the first 10 and the ones affiliated with the University of Kentucky are listed in the author section above. The authors of this article are collectively known as STAR Collaboration.

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