Abstract
We present next-to-leading order (NLO) calculations including QCD and electroweak (EW) corrections for 2ℓ2ν diboson signatures with two opposite-charge leptons and two neutrinos. Specifically, we study the processes ppto {e}^{+}{mu}^{-}{nu}_e{overline{nu}}_{mu } and ppto {e}^{+}{e}^{-}nu overline{nu} , including all relevant off-shell diboson channels, W+W−, ZZ, γZ, as well as non-resonant contributions. Photon-induced processes are computed at NLO EW, and we discuss subtle differences related to the definition and the renormalisation of the coupling α for processes with initial- and final-state photons. All calculations are performed within the automated Munich/Sherpa+OpenLoops frameworks, and we provide numerical predictions for the LHC at 13 TeV. The behaviour of the corrections is investigated with emphasis on the high-energy regime, where NLO EW effects can amount to tens of percent due to large Sudakov logarithms. The interplay between W W and ZZ contributions to the same-flavour channel, ppto {e}^{+}{e}^{-}nu overline{nu} , is discussed in detail, and a quantitative analysis of photon-induced contributions is presented. Finally, we consider approximations that account for all sources of large logarithms, at high and low energy, by combining virtual EW corrections with a YFS soft-photon resummation or a QED parton shower.
Highlights
Of nontrivial backgrounds in a broad range of measurements and searches
We present next-to-leading order (NLO) calculations including QCD and electroweak (EW) corrections for 2 2ν diboson signatures with two opposite-charge leptons and two neutrinos
In this paper we investigate the significance of the γ-induced production mode using state-of-the-art PDFs and taking into account NLO EW corrections, as well as realistic selection cuts on the 2 2ν final state
Summary
In the Standard Model, the signature of two opposite-charged leptons and missing energy is dominantly produced through pp → W +W −/ZZ → 2 2ν, i.e. with two types of diboson resonances that decay into two leptons and two neutrinos. The SF process pp → e+e−νμ/τ νμ/τ is dominated by resonant ZZ production in qqannihilation and subsequent Z → e+e− and Z → ννdecays Such double-resonant contributions are accompanied by all allowed topologies with sub-leading resonance structures, including diagrams with γ∗ → e+e− subtopologies, as well as other single- and non-resonant topologies. The corresponding amplitudes are built by coherently summing over all diagrams entering the two previously discussed DFWW and SFZZ channels This channel is referred to as SFWW/ZZ channel, and all diagrams shown in figures 1–2 are representatives of the tree-level diagrams contributing here. Due to the fact that the phase-space regions with resonant intermediate W +W − and ZZ states are typically distinct, the assumption is justified that the SFWW/ZZ cross section is dominated by the incoherent sum of double-resonant contributions of one and the other type, while the effect of quantum interferences is small.
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