Anomalous couplings in $Z\gamma$ events at NNLO+PS and improving $\nu \bar{\nu }\gamma$ backgrounds in dark-matter searches

Abstract

The measurement of the triple gauge couplings (TGCs) is a central part of diboson studies at the LHC. In this letter we consider the $Z\gamma$ process and include anomalous TGCs (aTGCs) in the event generation at next-to-next-to-leading order QCD accuracy (NNLO+PS) within the MiNNLO${}_{\mathrm{PS}}$ framework. While our implementation is fully general and applies to both $Z\to {\ell }^{+}{\ell }^{-}$ and $Z\to \nu \bar{\nu }$ decays, we focus here on the $\nu \bar{\nu }\gamma$ final state. After validation of our simulation of $\nu \bar{\nu }\gamma$ 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 $\nu \bar{\nu }\gamma$ background to photon plus missing energy signatures in dark-matter searches, and we compare MiNNLO${}_{\mathrm{PS}}$ predictions for $\nu \bar{\nu }\gamma$ production to recent 13 TeV data.

Comments: 17 pages, 5 figures, 3 tables