We have repeated the study of $ZH\rightarrow (\nu \bar
\nu,l^+l^-)b\bar b$ reported at Snowmass 96~\cite{snowmass96} using 
QFL$^\prime$ and found consistent results.  This analysis achieves
sensitivity via a tight selection which reduces the background to a
low level. 

\vspace{0.2in}
{\bf Event Samples}\\ \nopagebreak

The event samples used in this analysis were produced as described in
the section for the $WH\rightarrow\ell\nu\bb$ QFL$^\prime$ analysis.

\vspace{0.2in}
{\bf Selection Criteria}\\ \nopagebreak

For the $ZH\rightarrow \nu\bar \nu b\bar b$, We apply the following
kinematic selection criteria:
\begin{itemize}
  \item Raw $\met> 35$ GeV to pass the trigger requirement.
  \item Two $b$ tagged jets with $E_t>15$ GeV in $|\eta|<2.0$. 
  \item Minimum $\delta \phi_{min}>0.5$ between $\met$ 
 and any jets $E_t>8$ GeV and $|\eta|<2.0$. 
  \item No extra jet $Et>8$ GeV in $|\eta|<2.4$.
  \item No isolated track above 10 GeV in the events, where the isolation 
   requirement is $\Sigma P_t <2.0$ GeV over the additional tracks 
   inside the cone $\Delta R=0.4$.
\end{itemize} 

The numbers of observed events and the corresponding background
estimates for 1~fb$^{-1}$ at $\sqrt{s} = 2 $ TeV, are summarized in
Table~\ref{yao-table2}.  As in the $\ell\nu\bb$ channel, the
backgrounds are dominated by vector boson and top quark production.
Generic multijet events are removed very efficiently by the
requirements of two $b$ jets and large missing $\et$.  This background
is extremely difficult and unreliable to simulate due to the large
cross section and very small acceptance, and must be estimated with
real data.  In the CDF Run 1 Higgs search, the $\bb$ dijet background
was about half of the total.  With tighter selection criteria, such as
a back-to-back cut on the jet azimuth, the authors believe that this
background will represent no more than 50\% of the total without loss
of signal sensitivity.

\begin{table}[tbp]
\caption{$ZH\rightarrow \nn\bb$ channel, QFL$^\prime$ analysis.
The expected $ZH\rightarrow (\nu \bar \nu, l^+l^-) b\bar b$ 
 signal and background events per 1 fb$^{-1}$.}
\label{yao-table2}
\begin{center}
\begin{tabular}{lccccc}
%\hline
$M_{H}$ (GeV/c$^2$)  &  90 & 100 & 110 & 120  & 130 \\ \tableline
$\sigma_{ZH}$ (pb)  & 0.24 & 0.18 & 0.13 & 0.1 & 0.074 \\ 
$\epsilon_{ZH}$ ($\%$) & 1.5 & 1.7 & 2.1 & 1.7 & 1.2 \\ 
signal (S)  & 3.6 & 3.1 & 2.7 & 1.7 & 0.9 \\ \tableline 
backgrounds & & & & &\\ 
$Z\bb$, $Zc\bar{c}$ & 6.53 & 5.20 & 4.9 & 4.83 & 3.77 \\ 
$ZZ$                & 5.43 & 4.90 & 3.4 & 1.33 & 0.0 \\
top                 & 1.63 & 2.2 & 2.2 & 2.2 & 2.2 \\
background$^a$ (B)  & 13.6 & 12.3 & 10.4 & 8.3 & 5.9 \\ %\hline
\end{tabular}
$^a$This does not include $\bb$ dijet production
processes, which must be estimated from data; see text.\\
%\vspace{0.2in}
\end{center}
%\caption{$ZH\rightarrow \nn\bb$ channel, QFL$^\prime$ analysis.
%The expected $ZH\rightarrow (\nu \bar \nu, l^+l^-) b\bar b$ 
% signal and background events per 1 fb$^{-1}$.}
%\label{yao-table2}
\end{table}

