A measurement of hard double-partonic interactions in $W \rightarrow l\nu$ + 2 jet events using the ATLAS detector at the LHC

The production of W bosons in association with two jets has been investigated using protonproton collisions at a centre-of-mass energy of $\sqrt{s}$ = 7 TeV. The fraction of W + 2 jet events arising from double parton scattering was measured to be $f^R_{DP}$ = 0.16 $\pm$ 0.01 (stat) $\pm$ 0.03 (sys) for jets with transverse momentum pT > 20 GeV and rapidity |y| < 2:8. This corresponds to an effective cross section for hard double partonic interactions of $\sigma_{eff}$ = 11 $\pm$ 1 (stat)$^{+3}_{-2}$(sys) mb, which is consistent with previous measurements performed at lower centre-of-mass energies in different channels. This measurement was performed using data collected with the ATLAS detector corresponding to an integrated luminosity of 33 pb$^{-1}$.