\section{Preselection}
\label{sec:preselection}


\subsection{Stripping}

\subsection{not yet determined}
UNFINISHED
The middle \qsq-region is analysed.

To remove any contribution from the \jpsi mode, a cut requiring $1 < m^2_{\jpsi} < 6\gev$ is applied to the samples.

Trigger decision are applied on the samples as well. For the L0 stage, events that were triggered by hadronic, leptonic or global TIS events are allowed and merged into one sample. \hltone as well as \hlttwo trigger decision for TOS are kept.

As it turns out, there is most probably some kind of physical background reaching into our region of interest. In order to reduce the amount of background, strong cuts are applied.


%define explanations
\def \chisqvtxndfexpl {Reconstruction quality of the vertex per number of degrees of freedom}
\def \chisqvtxexpl {Reconstruction quality of the vertex}
\def \ptexpl {Transverse momentum}
\def \chisqfdexpl {\chisq of the fit to the flight distance}
\def \ghostprobaexpl {Probability that track is a ghost}
\def \amaxdocaexpl {Maximum distance of closest approach with all tracks}
\def \diraexpl {Cosine of angle between momentum and flight direction from best primary vertex}
\newcommand{\probnnexpl}[1]{Probability for the particle to be a #1}
\newcommand{\probnn}[1]{$ProbNN_{#1}$}


\subsection{Preselection cuts}
\begin{table}[t]
	\caption{
		%\small %captions should be a little bit smaller than main text
		Preselection cuts}
	\begin{center}\begin{tabularx}{\textwidth}{lrlX}
			\hline
			Particle& Variable 		& Cut 		& Explanation      \\ 
			\hline
			\Bu		& \chisqvtxndf	& $<6$		& \chisqvtxndfexpl\\
					& AMAXDOCA		& $<4$		& \amaxdocaexpl\\
					& \pt		& $>1\gev$	& Transverse momentum\\
					& $DIRA ownpv$	& $>0.9998$	& \diraexpl\\
					& ${\chisq}_{FD}$	& $>150$	& \chisqfdexpl\\
			
			\hline
			\jpsi	& \chisqip ownpv& $>1$		& \\
					& \chisqvtxndf	& $<6$		& \\
			
			\hline
			$\kaon_1$&\chisqip ownpv& $>3$		 \\
			
			\hline
			\Kp     & ProbNNk 		& $>0.02$	& \probnnexpl{\kaon} \\
					& GhostProb & $<0.3$	& \ghostprobaexpl \\
			
			\hline
			\pip and \pim & probNNpi		& $>0.02$	& \\
					& GhostProb & $<0.3$	& \ghostprobaexpl\\
					
			
			\hline
			\pip, \pim and \Kp & sum of \chisqip & $>200$ \\
			
			\hline
			\ep and \en & sum of \chisqip & $>200$	& \\
						& GhostProb & $<0.3$ & \ghostprobaexpl \\
			
			
			\hline
		\end{tabularx}\end{center}
		\label{tab:preselection}
	\end{table}