Measurement of hard double-parton interactions in W(→lν) + 2 jet events at √ s =7 TeV with the ATLAS detector

CERN-LHC. The production of W bosons in association with two jets in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV has been analysed for the presence of double-parton interactions using data corresponding to an integrated luminosity of 36 pb^-1, collected in 2010 with the ATLAS detector at the LHC. The fraction of events arising from double-parton interactions, f_{DP}^{(D)}, has been measured through the momentum balance between the two jets and amounts to f_{DP}^{(D)} = 0.08 +- 0.01 (stat.) +- 0.02 (sys) for jets with transverse momentum pT > 20 GeV and rapidity |y| < 2.8. This corresponds to a measurement of the effective area parameter for hard double-parton interactions of sigma_{eff} = 15 +- 3 (stat.) +5,-3 (sys.) mb.

Data points reverse engineered from Figure 9 of paper by Evgeny Slavin.