Abstract
Two-particle correlations are powerful tools for studying the medium produced in heavy-ion collisions. In particular, two-particle transverse momentum correlations enable measurements of the collision dynamics sensitive to momentum currents. Their evolution with collision centrality, which is related to the system lifetime, provides information about the shear viscosity, \(\eta {\text{/}}s\), and the system relaxation time, \({{\tau }_{\pi }}\). We report on measurements of two-particle transverse momentum correlations as a function of centrality in Pb‒Pb collisions using the ALICE detector at the LHC. The centrality dependence of the near side peak of the correlation function, particularly its longitudinal width, provides information about the shear viscosity of the produced medium. The data are compared to predictions from selected Monte Carlo models. The charge independent momentum correlator exhibits a longitudinal broadening from peripheral to central collisions that is qualitatively consistent with expectations from a model with viscous effects. An interpretation of the observed broadening in the context of this model will be discussed.
Similar content being viewed by others
REFERENCES
K. Adcox et al. (PHENIX Collab.), “Formation of dense partonic matter in relativistic nucleus-nucleus collisions at RHIC: Experimental evaluation by the PHENIX collaboration,” Nucl. Phys. A 757, 184–283 (2005); arXiv:nucl-ex/0410003 [nucl-ex].
S. Gavin and M. Abdel-Aziz, “Measuring shear viscosity using transverse momentum correlations in relativistic nuclear collisions,” Phys. Rev. Lett. 97, 162 302 (2006); arXiv:nucl-th/0606061 [nucl-th].
M. Sharma and C. A. Pruneau, “Methods for the study of transverse momentum differential correlations,” Phys. Rev. C 79, 024 905 (2009); arXiv:0810.0716 [nucl-ex].
K. Aamodt et al. (ALICE Collab.), “The ALICE experiment at the CERN LHC,” JINST 3, S08002 (2008).
B. B. Abelev et al. (ALICE Collab.), “Performance of the ALICE experiment at the CERN LHC,” Int. J. Mod. Phys. A 29, 1 430 044 (2014); arXiv:1402.4476 [nucl-ex].
S. Acharya et al. (ALICE Collab.), “Two particle differential transverse momentum and number density correlations in p-Pb and Pb-Pb at the LHC,” Phys. Rev. C 100, 044903 (2019); arXiv:1805.04422 [nucl-ex].
H. Agakishiev et al. (STAR Collab.), “Evolution of the differential transverse momentum correlation function with centrality in Au + Au collisions at \({\sqrt {{{S}_{{NN}}}} }\) = 200 GeV,” Phys. Lett. B 704, 467–473 (2011); arXiv:1106.4334 [nucl-ex].
B. Abelev et al. (ALICE Collab.), “Charge correlations using the balance function in Pb–Pb collisions at \({\sqrt {{{S}_{{NN}}}} }\) = 2.76 TeV,” Phys. Lett. B 723, 267–279 (2013); arXiv:1301.3756 [nucl-ex].
X.-N. Wang and M. Gyulassy, “HIJING: A Monte Carlo model for multiple jet production in p p, p A and A A collisions,” Phys. Rev. D 44, 3501–3516 (1991).
Z.-W. Lin, C. M. Ko, B.-A. Li, B. Zhang, and S. Pal, “A multi-phase transport model for relativistic heavy ion collisions,” Phys. Rev. C 72, 064 901 (2005); arXiv: nucl-th/0411110 [nucl-th].
P. Kovtun, D. T. Son, and A. O. Starinets, “Viscosity in strongly interacting quantum field theories from black hole physics,” Phys. Rev. Lett. 94, 111 601 (2005); arXiv: hep-th/0405231 [hep-th].
Author information
Authors and Affiliations
Consortia
Corresponding author
Rights and permissions
About this article
Cite this article
Gonzalez, V., the ALICE Collaboration. Two-Particle Transverse Momentum Correlations in Pb–Pb Collisions at \(\sqrt {{{{\text{s}}}_{{{\text{NN}}}}}} = 2.76\) TeV. Phys. Part. Nuclei 51, 340–344 (2020). https://doi.org/10.1134/S1063779620030120
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1134/S1063779620030120