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 with the ATLAS detector at the Large Hadron Collider. The fraction of events arising from double-parton interactions, $f_{DP}^{(D)}$, has been measured through the $p_{T}$ balance between the two jets and amounts to $f_{DP}^{(D)} = 0.08 \pm 0.01 (stat.) \pm 0.02 (sys.)$ for jets with transverse momentum $p_{T}$ 20 GeV and rapidity $|\gamma|< 2.8$. This corresponds to a measurement of the effective area parameter for hard double-parton interactions of $\sigma_{eff} = 15 \pm 3 (stat.)_{-3}^{+5} (sys.)$ mb.
number of pulisher's sheets:
2,5
affiliation:
Wydział Fizyki, Astronomii i Informatyki Stosowanej : Instytut Fizyki im. Mariana Smoluchowskiego