
\documentclass[border=5pt,multi=true]{standalone}
\usepackage{standalone}
\usepackage{ifthen}
\usepackage{microtype}
\usepackage{lineno}
\usepackage{xspace}
\usepackage{graphicx}
\usepackage{overpic}
\usepackage{color}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{amsfonts}
\usepackage{upgreek}
\usepackage{hyperref}
\usepackage{hypcap}
\usepackage{cite}
\usepackage{mciteplus}
\usepackage{longtable}

\begin{document}
\begin{tabular}{cccc}  
\hline
Combination    & $\eta$   & $\alpha$ (plug-in)    & $\alpha$ (profile likelihood) \\
\hline
 $ DK^\pm$ \xspace           & $0.6827$ $(1\sigma)$ & $0.6874 \pm 0.0050$ & $0.6508 \pm 0.0051$ \\
               & $0.9545$ $(2\sigma)$ & $0.9543 \pm 0.0023$ & $0.9414 \pm 0.0025$ \\
               & $0.9973$ $(3\sigma)$ & $0.9952 \pm 0.0007$ & $0.9947 \pm 0.0008$ \\
\hline
 $ D\pi^\pm$ \xspace          & $0.6827$ $(1\sigma)$ & $0.5945 \pm 0.0053$ & $0.5105 \pm 0.0054$ \\
               & $0.9545$ $(2\sigma)$ & $0.9391 \pm 0.0026$ & $0.9238 \pm 0.0029$ \\
               & $0.9973$ $(3\sigma)$ & $0.9960 \pm 0.0007$ & $0.9919 \pm 0.0010$ \\
\hline
 $ DK^\pm$ \xspace and  $ D\pi^\pm$ \xspace & $0.6827$ $(1\sigma)$ & $0.6394 \pm 0.0050$ & $0.5839 \pm 0.0051$ \\
               & $0.9545$ $(2\sigma)$ & $0.9374 \pm 0.0025$ & $0.9112 \pm 0.0030$ \\
               & $0.9973$ $(3\sigma)$ & $0.9929 \pm 0.0009$ & $0.9912 \pm 0.0010$ \\
\hline
\end{tabular}
\end{document}
