Multiplicity and transverse momentum dependence of two- and four-particle correlations in pPb and PbPb collisions

• Main Authors: CMS Collaboration (Author), Apyan, Aram (Contributor), Bauer, Gerry P (Contributor), Busza, Wit (Contributor), Cali, Ivan Amos (Contributor), Chan, Matthew Hans (Contributor), Di Matteo, Leonardo (Contributor), Dutta, Valentina (Contributor), Gomez-Ceballos, Guillelmo (Contributor), Goncharov, Maxim (Contributor), Kim, Yongsun (Contributor), Klute, Markus (Contributor), Lai, Yue Shi (Contributor), Levin, Amy Elizabeth (Contributor), Luckey Jr, P David (Contributor), Ma, Teng (Contributor), Nahn, Steven (Contributor), Paus, Christoph M. E. (Contributor), Ralph, Duncan Kelley (Contributor), Roland, Christof E (Contributor), Roland, Gunther M (Contributor), Stephans, George S. F. (Contributor), Stoeckli, Fabian (Contributor), Sumorok, Konstanty C (Contributor), Velicanu, Dragos Alexandru (Contributor), Wolf, Roger (Contributor), Wyslouch, Boleslaw (Contributor), Yang, Ming (Contributor), Yilmaz, Yetkin (Contributor), Yoon, A. S. (Contributor), Zanetti, Marco (Contributor), Wyslouch, Victoria (Contributor)
• Other Authors: Massachusetts Institute of Technology. Department of Physics (Contributor), Massachusetts Institute of Technology. Laboratory for Nuclear Science (Contributor)
• Format: Article
• Language: English
• Published: Elsevier, 2018-06-11T13:55:39Z.
• Subjects: Article
• Online Access: Get fulltext

 Measurements of two- and four-particle angular correlations for 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 31nb ⁻¹, were collected during the 2013 LHC pPb run at a nucleon-nucleon center-of-mass energy of 5.02 TeV by the CMS experiment. The results are compared to 2.76 TeV semi-peripheral PbPb collision data, collected during the 2011 PbPb run, covering a similar range of particle multiplicities. The observed correlations are characterized by the near-side (|δφ|≈0) associated pair yields and the azimuthal anisotropy Fourier harmonics (v[subscript n]). The second-order (v₂) and third-order (v₃) anisotropy harmonics are extracted using the two-particle azimuthal correlation technique. A four-particle correlation method is also applied to obtain the value of v₂ and further explore the multi-particle nature of the correlations. Both associated pair yields and anisotropy harmonics are studied as a function of particle multiplicity and transverse momentum. The associated pair yields, the four-particle v₂, and the v₃ become apparent at about the same multiplicity. A remarkable similarity in the v₃ signal as a function of multiplicity is observed between the pPb and PbPb systems. Predictions based on the color glass condensate and hydrodynamic models are compared to the experimental results. Keywords: CMS; Physics; Heavy ions