Solving the RAA ? υ 2 puzzle

[摘要] For the past ten years RAA(pT), the nuclear modification factor that encodes the suppression of high pTparticles due to energy loss within the medium was fairly well described by many theoretical models. However, the same models systematically underpredicted the high pTelliptic flow, υ2, which is experimentally measured as the correlation between soft and hard hadrons. All previous calculations neglected the effect of event-by-event fluctuations of an expanding viscous hydrodynamical background as well as the soft-hard flow harmonic correlations in the experimentally measured υ2. In this talk I show how event-by-event viscous hydrodynamics (computed using the v-USPhydro code) coupled to an energy loss model (BBMG) is able to simultaneously describe soft physics observables as well as the high-pTRAAand υ2. Suggestions for future more differential calculations at the LHC run2 are made to explore soft-hard flow correlations.

[发布机构] Department of Physics, University of Houston, Houston; TX; 77204, United States^1

[关键词] Differential calculation;Elliptic flows;Event-by-event fluctuations;Flow correlation;Harmonic correlation;Nuclear modification factors;Pt particle