Measurements of multiparticle azimuthal correlations (cumulants) for charged particles in p-Pb at √sNN = 5.02 TeV and Pb-Pb at √sNN = 2.76 TeV collisions are presented. They help address the question of whether there is evidence for global, flowlike, azimuthal correlations in the p-Pb system. Comparisons are made to measurements from the larger Pb-Pb system, where such evidence is established. In particular, the second harmonic two-particle cumulants are found to decrease with multiplicity, characteristic of a dominance of few-particle correlations in p-Pb collisions. However, when a |η| gap is placed to suppress such correlations, the two-particle cumulants begin to rise at high multiplicity, indicating the presence of global azimuthal correlations. The Pb-Pb values are higher than the p-Pb values at similar multiplicities. In both systems, the second harmonic four-particle cumulants exhibit a transition from positive to negative values when the multiplicity increases. The negative values allow for a measurement of v2{4} to be made, which is found to be higher in Pb-Pb collisions at similar multiplicities. The second harmonic six-particle cumulants are also found to be higher in Pb-Pb collisions. In Pb-Pb collisions, we generally find v2{4} ≃ v2{6} ̸= 0 which is indicative of a Bessel-Gaussian function for the v2 distribution. For very high-multiplicity Pb-Pb collisions, we observe that the four- and six-particle cumulants become consistent with 0. Finally, third harmonic two-particle cumulants in p-Pb and Pb-Pb are measured. These are found to be similar for overlapping multiplicities, when a |η| > 1.4 gap is placed.

Multiparticle azimuthal correlations in p-Pb and Pb-Pb collisions at the CERN Large Hadron Collider

ARNALDI, Roberta;BALA, RENU;BEOLE', Stefania;BERZANO, DARIO CARLO DOMENICO;L. Bianchi;BOTTA, Elena;BRUNA, ELENA;BUFALINO, STEFANIA;CORRALES MORALES, YASSER;FERRETTI, Alessandro;GAGLIARDI, Martino;GALLIO, Mauro;INNOCENTI, GIAN MICHELE;LATTUCA, ALESSANDRA;LEONCINO, MARCO;MASERA, Massimo;MILANO, LEONARDO;OPPEDISANO, Chiara;RAMELLO, Luciano;RIVETTI, Angelo;RUSSO, RICCARDO;SCOMPARIN, ENRICO;VALLERO, Sara;VERCELLIN, Ermanno;
2014-01-01

Abstract

Measurements of multiparticle azimuthal correlations (cumulants) for charged particles in p-Pb at √sNN = 5.02 TeV and Pb-Pb at √sNN = 2.76 TeV collisions are presented. They help address the question of whether there is evidence for global, flowlike, azimuthal correlations in the p-Pb system. Comparisons are made to measurements from the larger Pb-Pb system, where such evidence is established. In particular, the second harmonic two-particle cumulants are found to decrease with multiplicity, characteristic of a dominance of few-particle correlations in p-Pb collisions. However, when a |η| gap is placed to suppress such correlations, the two-particle cumulants begin to rise at high multiplicity, indicating the presence of global azimuthal correlations. The Pb-Pb values are higher than the p-Pb values at similar multiplicities. In both systems, the second harmonic four-particle cumulants exhibit a transition from positive to negative values when the multiplicity increases. The negative values allow for a measurement of v2{4} to be made, which is found to be higher in Pb-Pb collisions at similar multiplicities. The second harmonic six-particle cumulants are also found to be higher in Pb-Pb collisions. In Pb-Pb collisions, we generally find v2{4} ≃ v2{6} ̸= 0 which is indicative of a Bessel-Gaussian function for the v2 distribution. For very high-multiplicity Pb-Pb collisions, we observe that the four- and six-particle cumulants become consistent with 0. Finally, third harmonic two-particle cumulants in p-Pb and Pb-Pb are measured. These are found to be similar for overlapping multiplicities, when a |η| > 1.4 gap is placed.
2014
90
054901
054901
azimuthal correlations; p-Pb collisions; Pb-Pb collisions
B. Abelev;J. Adam;D. Adamová;M. M. Aggarwal;G. Aglieri Rinella;M. Agnello;A. Agostinelli;N. Agrawal;Z. Ahammed;N. Ahmad;I. Ahmed;S. U. Ahn...espandi
File in questo prodotto:
File Dimensione Formato  
PRC_90_2014_054901.pdf

Accesso aperto

Tipo di file: PDF EDITORIALE
Dimensione 810.8 kB
Formato Adobe PDF
810.8 kB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/157274
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 178
  • ???jsp.display-item.citation.isi??? 157
social impact