First observation of electroweak Z boson plus two jet production

Events with jets produced in association with a Z boson in proton-proton collisions can be used to study distributions sensitive to the vector boson fusion (VBF) process at CERN’s Large Hadron Collider. This process is interesting to study because of its similarity to the VBF production of a Higgs boson as well as its sensitivity to new physics via the WW Z triple gauge coupling. Evidence for electroweak Zjj production beyond the 5σ level is presented using data collected at a centre-of-mass energy of √ s = 8 TeV by the ATLAS experiment in 2012. This constitutes the first observation of a VBF-like process. The detector-corrected cross sections measured in two fiducial regions are in excellent agreement with the Standard Model expectations and have also been used to constrain anomalous triple gauge couplings. Furthermore, detectorcorrected cross sections and differential distributions for inclusive Zjj production are presented in different regions of phase space with varying sensitivity to the electroweak Zjj component. In addition, a performance study of the tracking algorithms used in the ATLAS high-level trigger system is presented.