Flow Dominance and Factorization of Transverse Momentum Correlations in Pb-Pb Collisions at the LHC

Summary, in English

We present the first measurement of the two-particle transverse momentum differential correlation function, P2≡ ΔpTΔpT/ pT2, in Pb-Pb collisions at sNN=2.76 TeV. Results for P2 are reported as a function of the relative pseudorapidity (Δη) and azimuthal angle (Δφ) between two particles for different collision centralities. The Δφ dependence is found to be largely independent of Δη for |Δη|≥0.9. In the 5% most central Pb-Pb collisions, the two-particle transverse momentum correlation function exhibits a clear double-hump structure around Δφ=π (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 |Δη|≥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. © 2017 CERN, for the ALICE Collaboration.

• Author: J. Adam; D. Adamova; M M Aggarwal; G Aglieri Rinella; M. Agnello; N Agrawal; Peter Christiansen; Martin Ljunggren; Anders Oskarsson; Tuva Richert; David Silvermyr; Evert Stenlund; Vytautas Vislavicius
• Department/s: Particle and nuclear physics
• Publishing year: 2017
• Language: English
• Publication/Series: Physical Review Letters
• Volume: 118
• Issue: 16
• Links: http://dx.doi.org/10.1103/PhysRevLett.118.162302
• Document type: Journal article
• Publisher: American Physical Society
• Topic: Subatomic Physics
• Keywords: Momentum; Tellurium compounds; Azimuthal angle; Collective motions; Differential correlation; Fourier decomposition; Pb-Pb collisions; Pseudorapidities; Transverse momenta; Two particles; Lead
• Status: Published
• ISBN/ISSN/Other: ISSN: 1079-7114