Measurement of the electroweak production cross section of the Z boson with two forward-backward jets in pp collisions at 7 TeV

A measurement of the electroweak production cross sections of the Z boson with two forward-backward jets in pp collisions at $\sqrt{s} = 7 \TeV$ is presented, based on 5 fb$^{-1}$ of data recorded by the CMS detector at the LHC. We estimate the value of the cross section of the electroweak $\ell\ell \rm j j$ production process and compare it with the theoretical cross section, calculated using the following parton level selections: $m_{\ell\ell} >50 \GeV$, $\pt^{\rm j} > 25 \GeV$, $|\eta ^{\rm j}|< 4.0$, $m_{\rm jj}>$120 GeV. The measurement, combining the muon and electron channels, gives the cross-section $\sigma_{\rm meas} = 154 \pm 24 (\rm stat) \pm 46 (\rm exp.syst) \pm 27 (\rm th.syst) \pm 3 (\rm lumi)$ fb, in an agreement with the theoretical cross section of 166 fb, calculated with the next-to-leading order QCD corrections. Results are also presented on the measurement of the hadronic activity in the rapidity difference between the two forward-backward jets. These measurements demonstrate the CMS detector and analysis capability to extract a process which is comparable in the cross-section and topologically with standard model Higgs boson produced via Vector Boson Fusion process.