Abstract
The second-order azimuthal anisotropy Fourier harmonics, , are obtained in and PbPb collisions over a wide pseudorapidity () range based on correlations among six or more charged particles. The -Pb data, corresponding to an integrated luminosity of , were collected during the 2013 LHC -Pb run at a nucleon-nucleon center-of-mass energy of by the CMS experiment. A sample of semiperipheral PbPb collision data at , corresponding to an integrated luminosity of and covering a similar range of particle multiplicities as the data, is also analyzed for comparison. The six- and eight-particle cumulant and the Lee-Yang zeros methods are used to extract the coefficients, extending previous studies of two- and four-particle correlations. For both the and PbPb systems, the 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 ) correlations in both systems. The ratios of values corresponding to correlations including different numbers of particles are compared to theoretical predictions that assume a hydrodynamic behavior of a 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.
- Received 18 February 2015
DOI:https://doi.org/10.1103/PhysRevLett.115.012301
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© 2015 CERN, for the CMS Collaboration
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