Measurement of momentum imbalance in $Z \rightarrow \ell\ell$ + Jet events in Lead-Lead collisions at $\sqrt{s_{NN}}$= 2.76 TeV with the ATLAS detector

The boson + jet probe, composed of a color neutral boson and color sensitive jet, has been called the `golden channel' for understanding the interactions of color sensitive objects in the quark gluon plasma. This analysis presents a study of azimuthally correlated $Z$ boson + jet events observed in the 2011 LHC Pb+Pb run at $\sqrt{s_{NN}}=2.76$ TeV using the ATLAS detector. $Z$ bosons are reconstructed via the $Z \rightarrow$ ee and $Z \rightarrow \mu\mu$ channels, and jets are reconstructed using the anti-$k_{t}$ algorithm following subtraction of the underlying event. A total of 36 $Z \rightarrow \ell\ell$ +jet events satisfy the analysis criteria, and the ratio of the transverse momenta of the jet to the $Z$ boson is studied. A suppression of this ratio in the data is observed, qualitatively consistent with jet energy loss.