The tricky azimuthal dependence of jet quenching at RHIC and LHC via CUJET2.0

Abstract

High transverse momentum neutral pion and charged hadron suppression pattern with respect to reaction plane at RHIC and LHC energies in central and semi-peripheral AA collisions are studied in a perturbative QCD based model, CUJET2.0. CUJET2.0 has dynamical DGLV radiation kernel and Thoma-Gyulassy elastic energy loss, with both being generalized to including multi-scale running strong coupling as well as energy loss probability fluctuations, and the full jet path integration is performed in a low $p_T$ flow data constrained medium which has 2+1D viscous hydrodynamical expanding profile. We find that in CUJET2.0, with only one control parameter, ${\alpha }_{max}$, the maximum coupling strength, fixed to be 0.26, the computed nuclear modification factor $R_{AA}$ in central and semi-peripheral AA collisions are consistent with RHIC and LHC data at average ${\chi }^2/d.o.f.<1.5$ level. Simultaneous agreements with high $p_T$ azimuthal anisotropy $v_2$ data are acquired given average ${\alpha }_{max}$ over in-plane and out-of-plane paths varying as little as 10\%, suggesting a non-trivial dependence of the high $p_T$ single particle $v_2$ on the azimuthally varied strong coupling.

Comments: 5 pages, 2 figures, elsarticle style; contributed talk by Jiechen Xu at Hard Probes 2013, Cape Town; version published in Nucl. Phys. A