Modifications to Di-Jet Hadron Pair Correlations in Au+Au Collisions at   sqrt(s_NN) = 200 GeV
  Azimuthal correlations of high-pT charged hadron pairs from (di-)jet-fragmentation are studied at mid-rapidity in Au+Au collisions at vsNN=200 GeV. The distribution of jet-associated partner hadrons (1.0< pT <2.5 GeV/c) per trigger hadron (2.5< pT <4.0 GeV/c) is found to vary with collision centrality, both in shape and in yield, indicating a significant effect of the nuclear collision medium on the (di-)jet fragmentation process. 
PHENIX Collaboration, S.S. Adler, et al