Study of double parton scattering using W + 2-jet events in proton-proton collisions at $ \sqrt{s} $ = 7 TeV

Double parton scattering is investigated in proton-proton collisions at $ \sqrt{s} $ = 7 TeV where the final state includes a W boson, which decays into a muon and a neutrino, and two jets. The data sample corresponds to an integrated luminosity of 5 fb −1 , collected with the CMS detector at the LHC. Observables sensitive to double parton scattering are investigated after being corrected for detector effects and selection efficiencies. The fraction of W + 2-jet events due to double parton scattering is measured to be 0 . 055 ± 0 . 002 (stat . ) ± 0 . 014 (syst . ). The effective cross section, σ eff , characterizing the effective transverse area of hard partonic interactions in collisions between protons is measured to be 20 . 7 ± 0 . 8(stat . ) ± 6 . 6(syst . )mb.