Speaker
Description
The scaling property of large-$p_\perp$ hadron suppression, $R_{\rm{AA}}(p_\perp)$, measured in heavy ion collisions at RHIC and LHC allows for the determination of the average parton energy loss $\langle \epsilon \rangle$ in quark-gluon plasma produced in a variety of collision systems and centrality classes. Rescaling $\langle \epsilon \rangle$ by the particle density allows for the determination of the effective path length dependence of parton energy loss. We find that $\langle \epsilon \rangle \propto L^\beta$ with $\beta=1.03\pm^{0.09}_{0.06}$, which is consistent with pQCD expectation of parton energy loss in a longitudinally expanding quark-gluon plasma. We demonstrate that the azimuthal anisotropy coefficient $v_2$ divided by the collision eccentricity follows the same scaling property as $R_{\rm{AA}}$, which is observed in data. Finally, a simply relation between $v_2(p_\perp)$ and $R_{\rm{AA}}(p_\perp)$ is found and confirmed by the correlation of the two independent measurements. This offers a new way to probe the $L$ dependence of parton energy loss using high-statistics measurements from the coming LHC Run 3.
