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Centrality dependence of dihadron correlations and azimuthal anisotropy harmonics in PbPb collisions at sqrt(s[NN]) = 2.76 TeV

S. Chatrchyan D. Sillou 1 M. Besancon 2 S. Choudhury 2 M. Dejardin 2 D. Denegri 2 B. Fabbro 2 J.L. Faure 2 F. Ferri 2 S. Ganjour 2 A. Givernaud 2 P. Gras 2 G. Hamel de Monchenault 2 P. Jarry 2 E. Locci 2 J. Malcles 2 M. Marionneau 2 L. Millischer 2 J. Rander 2 A. Rosowsky 2 I. Shreyber 2 M. Titov 2 S. Baffioni 3 F. Beaudette 3 L. Benhabib 3 L. Bianchini 3 M. Bluj 3 C. Broutin 3 Pierre Busson 3 C. Charlot 3 N. Daci 3 T. Dahms 3 L. Dobrzynski 3 S. Elgammal 3 R. Granier de Cassagnac 3 M. Haguenauer 3 P. Mine 3 C. Mironov 3 C. Ochando 3 P. Paganini 3 D. Sabes 3 R. Salerno 3 Y. Sirois 3 C. Thiebaux 3 C. Veelken 3 A. Zabi 3 J.-L. Agram 4 J. Andrea 4 D. Bloch 4 D. Bodin 4 J.-M. Brom 4 M. Cardaci 4 E.C. Chabert 4 C. Collard 4 E. Conte 4 F. Drouhin 4 C. Ferro 4 J.-C. Fontaine 4 D. Gele 4 U. Goerlach 4 S. Greder 4 P. Juillot 4 M. Karim 4 A.-C. Le Bihan 4 P. van Hove 4 F. Fassi 5 D. Mercier 5 C. Baty 6 S. Beauceron 7 N. Beaupere 7 M. Bedjidian 7 O. Bondu 7 G. Boudoul 7 D. Boumediene 7 H. Brun 7 J. Chasserat 7 R. Chierici 7 D. Contardo 7 P. Depasse 7 H. El Mamouni 6 A. Falkiewicz 7 J. Fay 7 S. Gascon 7 M. Gouzevitch 7 B. Ille 7 T. Kurca 7 T. Le Grand 7 M. Lethuillier 7 L. Mirabito 7 S. Perries 7 V. Sordini 7 S. Tosi 7 Y. Tschudi 7 P. Verdier 7 S. Viret 7
Abstract : 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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Submitted on : Tuesday, January 17, 2012 - 8:48:29 AM
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S. Chatrchyan, D. Sillou, M. Besancon, S. Choudhury, M. Dejardin, et al.. Centrality dependence of dihadron correlations and azimuthal anisotropy harmonics in PbPb collisions at sqrt(s[NN]) = 2.76 TeV. European Physical Journal C: Particles and Fields, Springer Verlag (Germany), 2012, 72, pp.2012. ⟨10.1140/epjc/s10052-012-2012-3⟩. ⟨in2p3-00660549⟩



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