Event-by-Event $\mathrm{Hydrodynamics}+\mathrm{Jet}$ Energy Loss: A Solution to the ${R}_{AA}\ensuremath{\bigotimes}{v}_{2}$ Puzzle

Event-by-Event $Hydrodynamics + Jet$ Energy Loss: A Solution to the $R_{A A} \otimes v_{2}$ Puzzle

Jacquelyn Noronha-Hostler, Barbara Betz, Jorge Noronha, and Miklos Gyulassy

Phys. Rev. Lett. 116, 252301 – Published 21 June 2016

Abstract

High $p_{T} > 10 GeV$ elliptic flow, which is experimentally measured via the correlation between soft and hard hadrons, receives competing contributions from event-by-event fluctuations of the low- $p_{T}$ elliptic flow and event-plane angle fluctuations in the soft sector. In this Letter, a proper account of these event-by-event fluctuations in the soft sector, modeled via viscous hydrodynamics, is combined with a jet-energy-loss model to reveal that the positive contribution from low- $p_{T}$ $v_{2}$ fluctuations overwhelms the negative contributions from event-plane fluctuations. This leads to an enhancement of high- $p_{T} > 10 GeV$ elliptic flow in comparison to previous calculations and provides a natural solution to the decade-long high- $p_{T}$ $R_{A A} \otimes v_{2}$ puzzle. We also present the first theoretical calculation of high- $p_{T}$ $v_{3}$ , which is shown to be compatible with current LHC data. Furthermore, we discuss how short-wavelength jet-medium physics can be deconvoluted from the physics of soft, bulk event-by-event flow observables using event-shape engineering techniques.

Received 25 February 2016

DOI:https://doi.org/10.1103/PhysRevLett.116.252301

Physics Subject Headings (PhySH)

Collective flow Hard scattering Relativistic heavy-ion collisions

Nuclear Physics

Authors & Affiliations

Jacquelyn Noronha-Hostler¹, Barbara Betz², Jorge Noronha³, and Miklos Gyulassy^4,5,6

¹Department of Physics, University of Houston, Houston, Texas 77204, USA
²Institute for Theoretical Physics, Goethe University, Max-von-Laue-Strasse 1, 60438 Frankfurt am Main, Germany
³Instituto de Física, Universidade de Sáo Paulo, C.P. 66318, 05315-970 São Paulo, SP, Brazil
⁴Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
⁵Department of Physics, Pupin Lab MS-5202, Columbia University, New York, New York 10027, USA
⁶Institute of Particle Physics and Key Laboratory of Quark and Lepton Physics (MOE), Central China Normal University, Wuhan 430079, China