CMS-PAS-HIN-14-002

CMS-PAS-HIN-14-002
Long-range two-particle correlations with K0S and Lambda in pPb and PbPb collisions
CMS Collaboration
2014

Abstract: Measurements of two-particle angular correlations between identified strange hadrons ( $\text{K}_{\text{S}}^{0}$ and $\Lambda$ / $\overline{\Lambda}$ )and unidentified charged particles, emitted in pPb collisions, are presented over a wide range in pseudorapidity and full azimuth. The data, corresponding to an integrated luminosity of approximately 35nb $^{-1}$ , were collected during the 2013 LHC pPb run at a nucleon-nucleon center-of-mass energy of 5.02TeV by the CMS experiment. The results are compared to 2.76TeV semi-peripheral PbPb collision data, collected during the 2011 PbPb run, covering a similar range of particle multiplicities. The $\text{K}_{\text{S}}^{0}$ and $\Lambda$ / $\overline{\Lambda}$ are reconstructed via their topological secondary decays. The observed long-range correlations are characterized by the second-order ( $v_2$ ) and third-order ( $v_3$ ) anisotropy harmonics of $\text{K}_{\text{S}}^{0}$ and $\Lambda$ / $\overline{\Lambda}$ , which are studied as a function of particle multiplicity and transverse momentum. For high-multiplicity pPb events, a particle-species dependence of $v_2$ and $v_3$ is observed. Divided by the number of constituent quarks, the $v_2$ and $v_3$ harmonics of $\text{K}_{\text{S}}^{0}$ and $\Lambda$ / $\overline{\Lambda}$ as a function of kinetic energy per quark fall on the same curve within 10--15 $\%$ for each multiplicity class. This scaling is better than that observed in peripheral PbPb collisions.
Links: CDS record (PDF) ; inSPIRE record ; Public twiki page ; CADI line (restricted) ; These preliminary results are superseded in this paper, PLB 742 (2015) 200. The superseded preliminary plots can be found here.

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