Search for dark matter at \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\sqrt{s}=13~\mathrm{TeV}$$\end{document}s=13TeV in final states containing an energetic photon and large missing transverse momentum with the ATLAS detector