  We perform a joint analysis of the data from PHENIX at RHIC and ALICE at LHC
on the nuclear modification factor $R_{AA}$. The computations are performed
within the light-cone path integral approach to induced gluon emission. Our
results show that slow variation of $R_{AA}$ from RHIC to LHC energies
indicates that the QCD coupling constant is suppressed in the quark-gluon
plasma produced at LHC.
