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\begin{document}
    
    .
    
    \begin{tabular}{l | c c c c  c }
    \toprule
    Observable   & Parameters  &    Fit mode \\ 
    \midrule 
\multirow{2}{*}{ $ f_s/f_d$ \xspace} &  $a(7\text{\,Te\kern -0.1em V}\xspace)$, $a(8\text{\,Te\kern -0.1em V}\xspace)$, $a(13\text{\,Te\kern -0.1em V}\xspace)$ & Free \\
  & $b(7\text{\,Te\kern -0.1em V}\xspace)$, $b(8\text{\,Te\kern -0.1em V}\xspace)$, $b(13\text{\,Te\kern -0.1em V}\xspace)$ & Free \\
\multirow{2}{*}{$\mathcal{B}( B\xspace\xspace^0_ s\xspace\xspace\xspace\!\rightarrow\xspace  D\xspace\xspace^-_ s\xspace\xspace\xspace\pi\xspace\xspace^+\xspace\xspace)$} &  $r_{AF}$     &   Gaussian constrained \\ 
 & $r_{E}$     &   Gaussian constrained \\ 
 $\mathcal{B}( B\xspace\xspace^0_ s\xspace\xspace\xspace\!\rightarrow\xspace  { J\xspace\mskip -3mu/\mskip -2mu\psi\xspace}\xspace\phi\xspace)$ &  $\mathcal{F}_R$ \xspace  &     Free \\
 & $S_1$    & Gaussian constrained \\
 &$S_2$, $S_3$, $S_4$ &   Gaussian constrained \\ 
        \bottomrule
    \end{tabular}
    
\end{document}
