Refraction of Gluon jet in QGP
  We introduce photon-like refraction for gluon jet in quark gluon plasma created in high energy nucleus-nucleus collisions. A quark jet goes straightly while a gluon jet is assumed to bend in the non-homogeneous medium. Combining refraction and energy loss, we calculate the away-side dihadron $\Delta\phi$ distribution in central $Au+Au$ collisions at RHIC energy. The dihadrons from quark-quark pair center around $\Delta\phi=\pi$, while the dihadrons from quark-gluon and gluon-gluon pair are deflected from $\Delta\phi=\pi$. The resulting distribution shows three peaks at intermediate $p_T$ since both quark-quark and quark-gluon are important. However we only observe one center peak at high $p_T$, where the quark-quark contribution dominates. These observation qualitatively agrees with the experiment data. 
Hanzhong Zhang and Enke Wang