Seminar in Hadronic Physics

High p_T π0 azimuthal anisotropy measurement from PHENIX: the influence of initial geometry and implication for the jet quenching

Jiangyong Jia

Stony Brook University

PHENIX recently published precision measurement of neutral pion azimuthal anisotropy in Au+Au collisions at sqrt(snn)=200 GeV in a broad p_T range (1-18 GeV/c) [1]. A striking observation is that the measured azimuthal anisotropy exceeds most pQCD based energy loss model calculations by almost 100%, even in the p_T regions (>10 GeV/c) where the perturbative methods were believed to be valid. However, most of these calculations have not considered some important uncertainties in the initial geometry, such as eccentricity fluctuations and saturation effects. In this talk, I present this new exciting measurement, followed by a detailed exploration of the uncertainties of the initial geometry using a jet absorption model [2], and a discussion on its implications for the current picture of energy loss.

[1] arXiv: 1006.3740
[2] arXiv: 1005.0645