We present the first measurement of the two-particle transverse momentum differential correlation function, P2â¡ ÎpTÎpT/ pT2, in Pb-Pb collisions at sNN=2.76 TeV. Results for P2 are reported as a function of the relative pseudorapidity (Îη) and azimuthal angle (ÎÏ) between two particles for different collision centralities. The ÎÏ dependence is found to be largely independent of Îη for |Îη|â¥0.9. In the 5% most central Pb-Pb collisions, the two-particle transverse momentum correlation function exhibits a clear double-hump structure around ÎÏ=Ï (i.e., on the away side), which is not observed in number correlations in the same centrality range, and thus provides an indication of the dominance of triangular flow in this collision centrality. Fourier decompositions of P2, studied as a function of the collision centrality, show that correlations at |Îη|â¥0.9 can be well reproduced by a flow ansatz based on the notion that measured transverse momentum correlations are strictly determined by the collective motion of the system.
Flow Dominance and Factorization of Transverse Momentum Correlations in Pb-Pb Collisions at the LHC
DE CARO, ANNALISA;DE GRUTTOLA, DANIELE;DE PASQUALE, Salvatore;FUSCO GIRARD, Mario;MENINNO, ELISA;PAGANO, PAOLA;VIRGILI, Tiziano;CALIVA', Alberto
2017-01-01
Abstract
We present the first measurement of the two-particle transverse momentum differential correlation function, P2â¡ ÎpTÎpT/ pT2, in Pb-Pb collisions at sNN=2.76 TeV. Results for P2 are reported as a function of the relative pseudorapidity (Îη) and azimuthal angle (ÎÏ) between two particles for different collision centralities. The ÎÏ dependence is found to be largely independent of Îη for |Îη|â¥0.9. In the 5% most central Pb-Pb collisions, the two-particle transverse momentum correlation function exhibits a clear double-hump structure around ÎÏ=Ï (i.e., on the away side), which is not observed in number correlations in the same centrality range, and thus provides an indication of the dominance of triangular flow in this collision centrality. Fourier decompositions of P2, studied as a function of the collision centrality, show that correlations at |Îη|â¥0.9 can be well reproduced by a flow ansatz based on the notion that measured transverse momentum correlations are strictly determined by the collective motion of the system.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.