Abstract
New measurements of rapidity-even dipolar flow, veven1, are presented for several transverse momenta, pT, and centrality intervals in Au+Au collisions at [see formula in PDF] = 200, 39 and 19.6 GeV, U+U collisions at [see formula in PDF] = 193 GeV, and Cu+Au, Cu+Cu, d+Au and p+Au collisions at [see formula in PDF] = 200 GeV. The veven1 shows characteristic dependencies on pT, centrality, collision system and [see formula in PDF], consistent with the expectation from a hydrodynamic-like expansion to the dipolar fluctuation in the initial state. These measurements could serve as constraints to distinguish between different initialstate models, and aid a more reliable extraction of the specific viscosity η/s.
Highlights
Heavy-ion collisions (HIC) at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC) are aimed at studying the properties of the strongly interacting quark-gluon plasma (QGP) created in such collisions
A crucial question in these studies was the role of initial-state fluctuations and their influence on the uncertainties associated with the extraction of η/s for the QGP produced in HIC [8, 9]
The values of ve1ven(pT) extacted for different centrality selections (0-10%, 10-20% and 20-30%) are shown in Fig. 2; the solid line in panel (a) shows the a hydrodynamic calculations with η/s = 0.16[14], which in good agreement with our measurements, the inset extracted shows the corresponding for several centralities at r√essuNlNts=fo2r0t0heGaesVs.oTcihaetevde1vmeno( pmTe)nvtualmuecsoinnsdeircvaatetiothneccoheaffiraccietenrti,stCic, pattern of a crossing apocihnatntgheatfsrhoimftsnwegiathtiv√e ve1ven( pT ) sNN
Summary
Heavy-ion collisions (HIC) at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC) are aimed at studying the properties of the strongly interacting quark-gluon plasma (QGP) created in such collisions. Recent studies have emphasized the use of anisotropic flow measurements to study the transport properties of the QGP [1,2,3,4,5,6,7]. A crucial question in these studies was the role of initial-state fluctuations and their influence on the uncertainties associated with the extraction of η/s for the QGP produced in HIC [8, 9]. This work emphasizes new measurements for rapidity-even dipolar flow, ve1ven, which could aid a distinction between different initial-state models and facilitate the extraction of η/s with better constraints. Where paT and pbT are the transvers momentum of particles (a) and (b), respectively, and δNF is a so-called non-flow (NF) term, which includes possible contributions from resonance decays, Bose-. The magnitude of ve1ven is related to the fluctuations-driven dipole asymmetry ε1 and η/s [14, 17, 18]
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