Evidence for Collective Multiparticle Correlations in p-Pb Collisions


Khachatryan V., Sirunyan A., Tumasyan A., Adam W., Bergauer T., Dragicevic M., ...More

Physical Review Letters, vol.115, no.1, 2015 (SCI-Expanded, Scopus) identifier identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 115 Issue: 1
  • Publication Date: 2015
  • Doi Number: 10.1103/physrevlett.115.012301
  • Journal Name: Physical Review Letters
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Yıldız Technical University Affiliated: Yes

Abstract

The second-order azimuthal anisotropy Fourier harmonics, v2, are obtained in p-Pb and PbPb collisions over a wide pseudorapidity (η) range based on correlations among six or more charged particles. The p-Pb data, corresponding to an integrated luminosity of 35nb-1, were collected during the 2013 LHC p-Pb run at a nucleon-nucleon center-of-mass energy of 5.02TeV by the CMS experiment. A sample of semiperipheral PbPb collision data at sNN=2.76TeV, corresponding to an integrated luminosity of 2.5μb-1 and covering a similar range of particle multiplicities as the p-Pb data, is also analyzed for comparison. The six- and eight-particle cumulant and the Lee-Yang zeros methods are used to extract the v2 coefficients, extending previous studies of two- and four-particle correlations. For both the p-Pb and PbPb systems, the v2 values obtained with correlations among more than four particles are consistent with previously published four-particle results. These data support the interpretation of a collective origin for the previously observed long-range (large Δη) correlations in both systems. The ratios of v2 values corresponding to correlations including different numbers of particles are compared to theoretical predictions that assume a hydrodynamic behavior of a p-Pb system dominated by fluctuations in the positions of participant nucleons. These results provide new insights into the multiparticle dynamics of collision systems with a very small overlapping region.