CMS-PAS-HIN-14-008

CMS-PAS-HIN-14-008
Pseudorapidity dependence of long-range two-particle correlations in pPb collisions with CMS
CMS Collaboration
2014

Abstract: CMS measurements of two-particle correlations of charged particles have previously been published for proton-proton (pp), proton-lead (pPb), and lead-lead (PbPb) systems.This paper studies how the two-particle correlations depend on the relative pseudorapidity of the trigger and associate particles ( $\Delta\eta$ ) utilizing a narrow $\eta$ range for the trigger particle. The data were collected during the 2013 pPb run at a nucleon-nucleon center-of-mass energy of 5.02 TeV. The near-side ( $\Delta\phi\approx 0$ ) jet-like correlation is assumed to be of a generalized Gaussian shape in $\Delta\eta$ , and fitted with a pedestal long-range pseudorapidity correlation (ridge) in high-multiplicity collisions. The latter is modeled by combinatorial background multiplied by a linear function in $\Delta\eta$ , which is found to describe the data well. The jet correlations are subtracted, and the remaining ridge correlations are studied versus $\Delta\eta$ for small seperation in relative azimuthal angle. Furthermore, the Fourier coefficients of the two-particle correlations are extracted for high-multiplicity collisions, with and without subtraction of jet contributions approximated by the scaled low-multiplicity collision data. The $\eta$ dependence of the azimuthal anisotropy parameters is reported.
Links: CDS record (PDF) ; inSPIRE record ; Public twiki page ; CADI line (restricted) ; These preliminary results are superseded in this paper, PRC 96 (2017) 014915. The superseded preliminary plots can be found here.

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