Centrality dependence of pion freeze-out radii in Pb-Pb collisions at root s(NN)=2.76 TeV

0458124 - ÚJF 2017 RIV US eng J - Journal Article
Adam, J. - Adamová, Dagmar - Bielčík, J. - Bielčíková, Jana - Broz, M. - Čepila, J. - Contreras, J. G. - Eyyubova, G. - Ferencei, Jozef - Křelina, M. - Křížek, Filip - Kučera, Vít - Kushpil, Svetlana - Mareš, Jiří A. - Petráček, V. - Pospíšil, Jan - Schulc, M. - Špaček, M. - Šumbera, Michal - Vajzer, Michal - Vaňát, Tomáš - Závada, Petr … Total 989 authors
Centrality dependence of pion freeze-out radii in Pb-Pb collisions at root s(NN)=2.76 TeV.
Physical Review. C. Roč. 93, č. 2 (2016), s. 024905. ISSN 0556-2813
R&D Projects: GA MŠMT(CZ) LG13031
Institutional support: RVO:68378271 ; RVO:61389005
Keywords : ALICE collaboration * Bose-Einstein correlations * heavy ion collisions
Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders; BF - Elementary Particles and High Energy Physics (FZU-D)
Impact factor: 3.820, year: 2016

We report on the measurement of freeze-out radii for pairs of identical-charge pions measured in Pb-Pb collisions at root s(NN) = 2.76 TeV as a function of collision centrality and the average transverse momentum of the pair k(T). Three-dimensional sizes of the system (femtoscopic radii), as well as direction-averaged one-dimensional radii are extracted. The radii decrease with k(T), 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 < dN(ch)/d eta >(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 root s(NN), a decrease in the ratio R-out/R-side 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.
Permanent Link: http://hdl.handle.net/11104/0258458