Abstract
A search is presented for production of dark matter particles recoiling against a leptonically decaying Z boson in 20.3 fb$^{-1}$ of pp collisions at $\sqrt{s}$=8 TeV with the ATLAS detector at the Large Hadron Collider. Events with large missing transverse momentum and two oppositely-charged electrons or muons consistent with the decay of a Z boson are analyzed. No excess above the Standard Model prediction is observed. Limits are set on the mass scale of the contact interaction as a function of the dark matter particle mass using an effective field theory description of the interaction of dark matter with quarks or with Z bosons. Limits are also set on the coupling and mediator mass of a model in which the interaction is mediated by a scalar particle.
Highlights
Events with large missing transverse momentum and two oppositely charged electrons or muons consistent with the decay of a Z boson are analyzed
Limits are set on the coupling and mediator mass of a model in which the interaction is mediated by a scalar particle
The mediator of the interaction is assumed to be heavy compared to the typical parton interaction energies involved, and the dark-matter particles are assumed to be produced in pairs
Summary
Events with large missing transverse momentum and two oppositely charged electrons or muons consistent with the decay of a Z boson are analyzed. For the subdominant WZ → lνlþl− background, the control region is characterized by three leptons: a pair of sameflavor, oppositely charged leptons for which the invariant mass is within the Z boson mass window, an additional electron or muon, and a reconstructed EmT iss > 80 GeV.
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