Anomalous couplings in Zγ events at NNLO+PS and improving νν¯γ backgrounds in dark-matter searches

The measurement of the triple gauge couplings (TGCs) is a central part of diboson studies at the LHC. In this letter we consider the Zγ process and include anomalous TGCs (aTGCs) in the event generation at next-to-next-to-leading order QCD accuracy (NNLO+PS) within the MINNLO_PS framework. While our implementation is fully general and applies to both Z→ℓ⁺ℓ⁻ and Z→νν¯ decays, we focus here on the νν¯γ final state. After validation of our simulation of νν¯γ events, for which NNLO+PS accuracy is achieved for the first time, the effects of aTGCs on various distributions are studied. Moreover, we show the relevance of NNLO+PS accuracy for the νν¯γ background to photon plus missing energy signatures in dark-matter searches, and we compare MINNLO_PS predictions for νν¯γ production to recent 13 TeV data.