# Search for dark matter at $\sqrt{s}=13$ TeV in final states containing an energetic photon and large missing transverse momentum with the ATLAS detector

## TL;DR

This paper reports a search for dark matter and new physics in events with energetic photons and missing transverse momentum at the LHC, setting exclusion limits on mediator and resonance masses based on ATLAS data.

## Contribution

It provides new exclusion limits on dark-matter mediators and scalar resonances using 13 TeV ATLAS data, extending previous constraints in these models.

## Key findings

- Excluded mediator masses below 750-1200 GeV for certain dark-matter models.
- Restricted the suppression scale M* to be above 790 GeV at 95% CL.
- Set limits on high-mass scalar resonance decaying to Zγ with neutrino decay channels.

## Abstract

Results of a search for physics beyond the Standard Model in events containing an energetic photon and large missing transverse momentum with the ATLAS detector at the Large Hadron Collider are reported. As the number of events observed in data, corresponding to an integrated luminosity of 36.1 $\textrm fb^{-1}$ of proton-proton collisions at a centre-of-mass energy of 13 TeV, is in agreement with the Standard Model expectations, exclusion limits in models where dark-matter candidates are pair-produced are determined. For dark-matter production via an axial-vector or a vector mediator in the s-channel, this search excludes mediator masses below 750-1200 GeV for dark-matter candidate masses below 230-480 GeV at 95% confidence level, depending on the couplings. In an effective theory of dark-matter production, the limits restrict the value of the suppression scale $M_{*}$ to be above 790 GeV at 95% confidence level. A limit is also reported on the production of a high-mass scalar resonance by processes beyond the Standard Model, in which the resonance decays to $Z\gamma$ and the Z boson subsequently decays into neutrinos.