Centrality dependence of pion freeze-out radii in Pb-Pb collisions at √sNN = 2.76 TeV

Adam, J. and Antičić, Tome and Erhardt, Filip and Planinić, Mirko and Poljak, Nikola and Simatović, Goran and Utrobičić, Antonija and Zyzak, M. (ALICE Collaboration) (2016) Centrality dependence of pion freeze-out radii in Pb-Pb collisions at √sNN = 2.76 TeV. Physical Review C, 93 (2). pp. 24905-18. ISSN 0556-2813

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Abstract

We report on the measurement of freeze-out radii for pairs of identical-charge pions measured in Pb-Pb collisions at √sNN = 2.76 TeV as a function of collision centrality and the average transverse momentum of the pair kT. Three-dimensional sizes of the system (femtoscopic radii), as well as direction-averaged onedimensional radii are extracted. The radii decrease with kT, following a power-law behavior. This is qualitatively consistent with expectations from a collectively expanding system, produced in hydrodynamic calculations. The radii also scale linearly with 〈dNch/dη〉1/3. This behavior is compared to world data on femtoscopic radii in heavy-ion collisions. While the dependence is qualitatively similar to results at smaller √sNN, a decrease in the ratio Rout/Rside is seen, which is in qualitative agreement with a specific prediction from hydrodynamic models: a change from inside-out to outside-in freeze-out configuration. The results provide further evidence for the production of a collective, strongly coupled system in heavy-ion collisions at the CERN Large Hadron Collider.

Item Type: Article
Date: 4 February 2016
Subjects: NATURAL SCIENCES > Physics
Additional Information: Copyright (2016) by the American Physical Society. Received 29 July 2015.; published 4 February 2016.
Divisions: Faculty of Science > Department of Physics
Publisher: American Physical Society
Depositing User: Nikola Poljak
Date Deposited: 09 May 2016 19:28
Last Modified: 09 May 2016 19:28
URI: http://digre.pmf.unizg.hr/id/eprint/4522

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