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

TL;DR

This paper measures the rate of double-parton interactions in W+2 jet events at 7 TeV using ATLAS data, providing the first estimate of the effective interaction area for such processes.

Contribution

It presents the first measurement of the double-parton interaction fraction and the effective area parameter in W+2 jet events at the LHC.

Findings

Double-parton interaction fraction fDP(D) = 0.08 +- 0.01 (stat.) +- 0.02 (sys)

Effective area parameter σ_eff = 15 +- 3 (stat.) +5 -3 (sys.) mb

Method based on jet momentum balance to identify double-parton events

Abstract

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, collected with the ATLAS detector at the LHC. The fraction of events arising from double-parton interactions, fDP(D) has been measured through the momentum balance between the two jets and amounts to fDP(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.