LHC constraints on scalar diquarks

A number of years ago, low-energy constraints on scalar diquarks, particles that couple to two quarks, were examined. It was found that the two most weakly-constrained diquarks are Du and Dd, colour antitriplets that couple to uRiuRj\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ {u}_R^i{u}_R^j $$\end{document} and dRidRj\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ {d}_R^i{d}_R^j $$\end{document}, respectively. These diquarks have not been observed at the LHC. In this paper, we add the LHC measurements to the low-energy analysis, and find that the constraints are significantly improved. As an example, denoting xu as the Du coupling to the first and second generations, for MDu\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ {M}_{D^u} $$\end{document} = 600 GeV, the low-energy constraint is |xu| ≤ 14.4, while the addition of the LHC dijet measurement leads to |xu| ≤ 0.13–0.15. Further improvements are obtained by adding the measurement of single top production with a pT cut. These new constraints must be taken into account in making predictions for other low-energy indirect effects of diquarks.