Measurements of di-jets in p+p and Au+Au in the STAR experiment
  Jets are produced from hard scatterings in the early stages of heavy-ion collisions. It is expected that these high-p$_T$ partons travel through the hot and dense medium before fragmenting. Therefore they are expected to suffer energy loss in the QGP via gluon radiation or elastic collisions along their path. Measurements from full jet reconstruction help in the understanding of energy loss and its effect{\ss} on the jet structure and energy profile. A data-driven characterization of the background in Au+Au is needed in order to compare the results to p+p. The large coverage of the STAR detector along with an online trigger also allows for reconstructing di-jets. Suitable selection of trigger jets allows for studying a subset of jets on the recoil side which are biased towards higher energy loss because of a larger, on average, in-medium path length traversed. Trigger jets are also used to study jet-hadron correlations as an independent measurement to assess the effect of energy loss on the recoil side. We present measurements of di-jets and jet-hadron correlations in the presence of reconstructed di-jets in Au+Au and p+p at 200 GeV in the STAR experiment. 
Elena Bruna (for the STAR Collaboration)
nucl-ex