  The nuclear suppression factor R_AA of single inclusive hadrons measured in
ultrarelativistic heavy-ion collisions was the first observable to study jet
quenching, i.e. the final state interaction of hard parton showers with the
surrounding bulk matter. While its transverse momentum (P_T) dependence of R_AA
observed at RHIC was weak and hence never decisive in constraining models,
there is now a strong and non-trivial P_T dependence observed at the LHC. This
has been a challenge for several models which worked well at RHIC kinematics.
However, in more general terms it is also of importance to understand what
physical properties of the hard process and the parton-medium interaction are
reflected in R_AA(P_T). The results of the work presented here suggest that the
two main effects underlying the P_T dependence are the Quantum-Chromodynamics
scale evolution of the fragmentation function and the limited distance (set by
the typical medium length scale) for which a shower evolves in the medium.
