# Measurements of four-lepton production at the $Z$ Resonance in $pp$ Collisions at $s=7$ and 8 TeV with ATLAS

Aad, G. et al. (2014) Measurements of four-lepton production at the $Z$ Resonance in $pp$ Collisions at $s=7$ and 8 TeV with ATLAS. Physical Review Letters, 112(231806),

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## Abstract

Measurements of four-lepton (4ℓ, ℓ=e,μ) production cross sections at the Z resonance in pp collisions at the LHC with the ATLAS detector are presented. For dilepton and four-lepton invariant mass regions mℓ+ℓ−>5  GeV and 80<m4ℓ<100  GeV, the measured cross sections are 76±18(stat)±4(syst)±1.4(lumi)  fb and 107±9(stat)±4(syst)±3.0(lumi)  fb at s√=7 and 8 TeV, respectively. By subtracting the nonresonant 4ℓ production contributions and normalizing with Z→μ+μ− events, the branching fraction for the Z boson decay to 4ℓ is determined to be (3.20±0.25(stat)±0.13(syst))×10−6, consistent with the standard model prediction.