Measurement of four-jet production in proton-proton collisions at sqrt(s) =7 TeV

Measurements of the differential cross sections for the production of exactly four jets in proton-proton collisions are presented as a function of the transverse momentum pT and pseudorapidity η, together with the correlations in azimuthal angle and the pT balance among the jets. The data sample was collected in 2010 at a center-of-mass energy of 7 TeV with the CMS detector at the LHC, with an integrated luminosity of 36 inverse picobarns. The cross section for a final state with a pair of hard jets with pT> 50 GeV and another pair with pT> 20 GeV within abs(eta) < 4.7 is measured to be σ(pp→4j+X) = 330 ± 5 (stat.) ± 45 (syst.) nb. The measured differential cross sections agree with predictions involving parton showers in only some regions of the phase space. It is found that including a contribution from double parton scattering in the models brings the predictions closer to the measurements.