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Paper   IPM / Particles / 12361
School of Particles and Accelerator
  Title:   Centrality dependence of dihadron correlations and azimuthal anisotropy harmonics in PbPb collisions at sqrt(s[NN]) = 2.76 TeV
1.  Hessamadin Arfaei
2.  Hamed Bakhshiansohi
3.  Seyed Mohsen Etesami
4.  Ali Fahim
5.  Majid Hashemi
6.  Hoda Hesari
7.  Abideh Jafari
8.  Mohsen Khakzad
9.  A Mohammadi
10.  Mojtaba Mohammadi Najafabadi
11.  Saeid Paktinat
12.  Batool Safarzadeh
13.  Maryam Zeinali
  Status:   Published
  Journal: Eur. Phys. J. C
  No.:  2012
  Vol.:  72
  Year:  2012
  Supported by:  IPM
Measurements from the CMS experiment at the LHC of dihadron correlations for charged particles produced in PbPb collisions at a nucleon-nucleon centre-of-mass energy of 2.76 TeV are presented. The results are reported as a function of the particle transverse momenta (pt) and collision centrality over a broad range in relative pseudorapidity [Delta(eta)] and the full range of relative azimuthal angle [Delta(phi)]. The observed two-dimensional correlation structure in Delta(eta) and Delta(phi) is characterised by a narrow peak at Delta(eta), Delta(phi) approximately (0, 0) from jet-like correlations and a long-range structure that persists up to at least - Delta(eta) - = 4. An enhancement of the magnitude of the short-range jet peak is observed with increasing centrality, especially for particles of pt around 1-2 GeV/c. The long-range azimuthal dihadron correlations are extensively studied using a Fourier decomposition analysis. The extracted Fourier coefficients are found to factorise into a product of single-particle azimuthal anisotropies up to pt approximately 3-3.5 GeV/c for at least one particle from each pair, except for the second-order harmonics in the most central PbPb events. Various orders of the single-particle azimuthal anisotropy harmonics are extracted for associated particle pt of 1-3 GeV/c, as a function of the trigger particle pt up to 20 GeV/c and over the full centrality range

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