From Hydrodynamics to Jet Quenching, Coalescence, and Hadron Cascade: A Coupled Approach to Solving the RAA ⨷ v2 Puzzle

Abstract

Hydrodynamics and jet quenching are responsible for the elliptic flow v2 and suppression of large transverse momentum (pT) hadrons, respectively, two of the most important phenomena leading to the discovery of a strongly coupled quark-gluon plasma in high-energy heavy-ion collisions. A consistent description of the hadron suppression factor RAA and v2, especially at intermediate pT, however, remains a challenge. We solve this long-standing RAA⨷ v2 puzzle by including quark coalescence for hadronization and final state hadron cascade in the coupled linear Boltzmann transport-hydro model that combines concurrent jet transport and hydrodynamic evolution of the bulk medium. We illustrate that quark coalescence and hadron cascade, two keys to solving the puzzle, also lead to a splitting of v2 for pions, kaons, and protons in the intermediate pT region. We demonstrate for the first time that experimental data on RAA, v2, and their hadron flavor dependence from low to intermediate and high pT in high-energy heavy-ion collisions can be understood within this coupled framework.