Differential Z+ jets cross section measurements at 8 TeV in multijet final states

We present a measurement of the cross section of Z/γ⁎ plus jet events in proton-proton collisions as a function of the vector boson transverse momentum. The data were collected with the CMS detector at s=8 TeV , corresponding to an integrated luminosity of 19.7 fb −1 . The measurement is performed for vector bosons that have a transverse momentum larger than pT>40 GeV and for different jet multiplicities. We consider MadGraph [1] , Sherpa [2] and BlackHat + Sherpa [3] for Monte Carlo simulation (MC). MadGraph and Sherpa are multi-leg, leading-order matrix elements with parton showering programmes while BlackHat is an NLO parton-level MC. We also study the variables pTZ/HT and log10⁡(pTZ/pTj1) which are suitable to challenge the validity of NLO predictions. In hadronic searches for new physics, pTZ/HT would correspond to a E̸T/HT ratio.