Diff for /ttbar/p20_taujets_note/NN.tex between versions 1.2 and 1.3

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 \section{\label{sub:NN}Neural Network Analysis}  \section{\label{sub:NN}Neural Network Analysis}
   
 \subsection{\label{sub:Variables}Variables for NN training}  \subsection{\label{sub:Variables}Variables for NN training}
   
 \noindent Following the same procedure as in the previous analysis, we determine the content  \noindent Following the same procedure as in the p17 analysis, we determine the content
 of signal and background in the preselected sample, increase signal/background rate  of signal and background in the preselected sample, increase signal/background rate
 and from this, measure the cross-section.  and from this, measure the cross section.
 The procedure adopted in the p17 analysis was feed a set of topological variables into an  In p17, an artificil neural network based on topological characteristics of an event was used to
 artificial neural network in order to provide the best possible separation between  extract signal from a background-enriched region. As before, the criteria used in choosing the variables were:
 signal and background. As before, the criteria for choosing such variables were: power of discrimination  power of discrimination and $\tau$-uncorrelated variables. The following variables were considered:
 and $\tau$-uncorrelated variables. The set is presented below:  
   
 \begin{itemize}  \begin{itemize}
 \item \textit{\textbf{$H_{T}$}} - the scalar sum of all jet's $p_{T}$ (here and below including $\tau$ lepton candidates).   \item \textit{\textbf{$H_{T}$}} - The scalar sum of all jet $p_{T}$'s (here and below including $\tau$ lepton candidates). 
   For $H_{T}$ values above $\sim$ 200 GeV we observed a dominance of signal over background.
   
 \item \textit{\textbf{$\not\!\! E_{T}$ significance}} - As being the variable that provides the best signal-background  \item \textit{\textbf{$\not\!\! E_{T}$ significance}} - It is computed from calculated resolutions of 
 separation we decided to optimize it.  physical objects (jets, electrons, muons and unclustered energy) \cite{p17_note,METsig}. 
   It was chosen to be used and optimized due to its good signal-background discrimination power.
   
 \item \textit{\textbf{Aplanarity}} \cite{p17topo} - the normalized momentum tensor is defined as  \item \textit{\textbf{Aplanarity}} \cite{p17topo} - the normalized momentum tensor is defined as
   
 \begin{center}  \begin{center}
 \begin{equation}  \begin{equation}
 {\cal M} = \frac{\sum_{o}p^{o}_{i}p^{o}_{j}}{\sum_{o}|\overrightarrow{p^{o}}|}  {\cal M}_{ab} \equiv \frac{\sum_{i}p_{ia}p_{ib}}{\sum_{i}p^{2}_{i}}
 \label{tensor}  \label{tensor}
 \end{equation}  \end{equation}
 \end{center}  \end{center}
   
 \noindent where $\overrightarrow{p^{0}}$ is  the momentum-vector of a reconstructed object $o$  \noindent where $p_{i}$ is  the momentum-vector
 and $i$ and $j$ are cartesian coordinates. From the diagonalization of $\cal M$ we find three eigenvalues  and teh index $i$ runs over all the jets and the $W$. From the diagonalization of $\cal M$ we find three eigenvalues
 $\lambda_{1}\geq\lambda_{2}\geq\lambda_{3}$ with the constraint $\lambda_{1} + \lambda_{2} + \lambda_{3} = 1$.  $\lambda_{1}\geq\lambda_{2}\geq\lambda_{3}$ with the constraint $\lambda_{1} + \lambda_{2} + \lambda_{3} = 1$.
 The aplanarity {\cal A} is given by {$\cal A$} = $\frac{3}{2}\lambda_{3}$ and measures the flatness of an event.  The aplanarity is defined as {$\cal A$} = $\frac{3}{2}\lambda_{3}$ and measures the flatness of an event.
 Hence, it is defined in the range $0 \leq {\cal M} \leq 0.5$. Large values of {$\cal A$} correspond to more spherical events,  It assumes values in the range $0 \leq {\cal A} \leq 0.5$. 
 like $t\bar{t}$ events for instance, since they are typical of decays of heavy objects. On the other hand,  It was chosen to be used in the NN due to the fact that large values of {$\cal A$} correspond to more spherical events,
 both QCD and $W + \mbox{jets}$ events are more planar since jets in these events are primarily due to  like $t\bar{t}$ events for instance, since they are typical of cascade decays of heavy objects. On the other hand,
   both QCD and $W + \mbox{jets}$ events tend to be more collinear since jets in these events are primarily due to
 initial state radiation.  initial state radiation.
   
 \item \textit{\textbf{Sphericity}} \cite{p17topo} - being defined as {$\cal S$} = $\frac{3}{2}(\lambda_{2} + \lambda_{3})$,  \item \textit{\textbf{Sphericity}} \cite{p17topo} - Defined as {$\cal S$} = $\frac{3}{2}(\lambda_{2} + \lambda_{3})$,
 and having a range $0 \leq {\cal S} \leq 1.0$, sphericity is a measure of the summed $p^{2}_{\perp}$ with   and ranges as $0 \leq {\cal S} \leq 1.0$, sphericity is a measure of the summed $p^{2}_{\perp}$
 respect to the event axis. In this sense a 2-jets event corresponds to {$\cal S$} $\approx 0$ and an isotropic event  More isotropic events have {$\cal S$} $\approx 1$ while less isotropic ones have {$\cal S$} $\approx 0$. 
 {$\cal S$} $\approx 1$. $t\bar{t}$ events are very isotropic as they are typical of the decays of heavy objects  Sphericity is a good discrminator since $t\bar{t}$ events are very isotropic as they are typical of the decays of heavy objects
 and both QCD and $W + \mbox{jets}$ events are less isotropic due to the fact that jets in these events come   and both QCD and $W + \mbox{jets}$ events are less isotropic due to the fact that jets in these events come 
 primarily from initial state radiation.  primarily from initial state radiation.
   
Line 48  $L\equiv\left(\frac{M_{3j}-m_{t}}{\sigma Line 50  $L\equiv\left(\frac{M_{3j}-m_{t}}{\sigma
 where $m_{t}, M_{W},\sigma_{t},\sigma_{W}$ are top and W masses (172.4  where $m_{t}, M_{W},\sigma_{t},\sigma_{W}$ are top and W masses (172.4
 GeV and 81.02 GeV respectively) and resolution values (19.4 GeV and 8.28  GeV and 81.02 GeV respectively) and resolution values (19.4 GeV and 8.28
 GeV respectively). $M_{3j}$ and $M_{2j}$ are invariant masses composed  GeV respectively). $M_{3j}$ and $M_{2j}$ are invariant masses composed
 of the jet combinations. We choose combination that minimizes $L$.   of  2- and 3-jet combinations. We choose combination that minimizes $L$. 
   
 \item \textit{\textbf{Centrality}}, defined as $\frac{H_{T}}{H_{E}}$ , where $H_{E}$ is sum  \item \textit{\textbf{Centrality}}, defined as $\frac{H_{T}}{H_{E}}$ , where $H_{E}$ is sum
 of energies of the jets.   of energies of the jets. Used as discrimination variable since highe values ($\sim$ 1.0) are 
   more signal-dominated while low values ($\sim$ 0) are more background-dominated.
   
 \item \textit{\textbf{$\cos(\theta*)$}} -  The angle between the beam axis and the   \item \textit{\textbf{$\cos(\theta*)$}} -  The angle between the beam axis and the 
 highest-$p_T$ jet in the rest frame of all the jets in the event.  highest-$p_T$ jet in the rest frame of all the jets in the event. $t\bar{t}$ events tend to have
 \item \textit{\textbf{$\sqrt(s)$}} - The invariant mass of all jets and $\tau$s in the event.  a lower ($\sim$ 0) $\cos(\theta*)$ values. This motivated its choice.
   
   \item \textit{\textbf{$M_{jj\tau}$}} - The invariant mass of all jets and $\tau$s in the event.
   
 \end{itemize}  \end{itemize}
   
Line 62  The chosen variables are in the end a co Line 68  The chosen variables are in the end a co
 analysis: use events from the QCD-enriched   analysis: use events from the QCD-enriched 
 loose-tight sample to model QCD events in the signal-rich sample, and use  loose-tight sample to model QCD events in the signal-rich sample, and use
 a b-tag veto sample as an independent control sample to check the validity of such   a b-tag veto sample as an independent control sample to check the validity of such 
 background modeling.  background modeling. Plots of all variables described above are found in Appendix \ref{app:discri_var}.
   
 %\clearpage  %\clearpage
   
Line 70  background modeling. Line 76  background modeling.
 For training the Neural Network we used the Multilayer Perceptron algorithm, as described in   For training the Neural Network we used the Multilayer Perceptron algorithm, as described in 
 \cite{MLPfit}. As explained before in Section \ref{sub:Results-of-the}, the first 1400000   \cite{MLPfit}. As explained before in Section \ref{sub:Results-of-the}, the first 1400000 
 events in the ``loose-tight'' sample were used as background   events in the ``loose-tight'' sample were used as background 
 for NN training for taus types 1 and 2, and the first 600000 of the same sample for NN training for type 3 taus.  for NN training for taus of Types 1 and 2, and the first 600000 of the same sample for NN training for type 3 taus.
 This means that different tau types are being treated separately in the topological NN.  
 In both cases 1/3 of the Alpgen sample of $t\bar{t} \rightarrow \tau +jets$ was used for NN training and 2/3 of it  In both cases 1/3 of the Alpgen sample of $t\bar{t} \rightarrow \tau +jets$ was used for NN training and 2/3 of it
 for the measurement.  for the measurement.
 When doing the measurement later on (Section \ref{sub:xsect}) we pick the tau with the highest $NN(\tau)$  When doing the measurement later on (Section \ref{sub:xsect}) we pick the tau with the highest $NN(\tau)$
Line 88  the signal-enriched region. Line 93  the signal-enriched region.
   
   
 \begin{figure}[h]  \begin{figure}[h]
 \includegraphics[scale=0.6]{plots/SetI_NNout_SM_type2_tauQCD.eps}  \includegraphics[scale=0.49]{plots/SetI_NNout_SM_type2_tauQCD.eps}
 \caption{Training of topological Neural Network output for type 1 and 2 $\tau$ channel.   \caption{Training of topological Neural Network output for Type 1 and 2 $\tau$ channel combined. 
 Upper left: relative impact of each of the input variables; upper right: topological structure;  Upper left: relative impact of each of the input variables; upper right: relative weights
 lower right: final signal-background separation of the method; lower left: convergence curves.}  of the synaptic connections of the trained network;
   lower left: convergence curves; lower right: the output distribution of signal and background
   test samples after training.}
 \label{fig:nnout_type2_training}  \label{fig:nnout_type2_training}
 \end{figure}  \end{figure}
   
 \newpage  %\newpage
   
   
 \begin{figure}[h]  \begin{figure}[h]
 \includegraphics[scale=0.6]{plots/SetI_NNout_SM_type3_tauQCD.eps}  \includegraphics[scale=0.49]{plots/SetI_NNout_SM_type3_tauQCD.eps}
 \caption{Training of topological Neural Network output for type 3 $\tau$ channel.   \caption{Training of topological Neural Network output for type 3 $\tau$ channel. 
 Upper left: relative impact of each of the input variables; upper right: topological structure;  Upper left: relative impact of each of the input variables; upper right: relative weights
 lower right: final signal-background separation of the method; lower left: convergence curves.}  of the synaptic connections of the trained network;
   lower left: convergence curves; lower right: the output distribution of signal and background
   test samples after training.}
 \label{fig:nnout_type3_training}  \label{fig:nnout_type3_training}
 \end{figure}  \end{figure}
   
Line 148  level in order to have a consistent cut Line 157  level in order to have a consistent cut
 Below we describe how we split this part of the analysis into two parts:  Below we describe how we split this part of the analysis into two parts:
   
 \begin{enumerate}  \begin{enumerate}
 \item {\bf Set optimization:} We applied an arbitrary cut on $\not\!\! E_{T}$ significance of $\geq$ 4.0 and   \item {\bf Set optimization:} We applied an ``reasonable'' cut on $\not\!\! E_{T}$ significance of $\geq$ 4.0 and 
 varied the set of varibles going into NN training  varied the set of varibles going into NN training.
 \item {\bf $\not\!\! E_{T}$ significance optimization:} After chosing the best set based on the lowest RMS,   \item {\bf $\not\!\! E_{T}$ significance optimization:} After chosing the best set based on the lowest RMS of the
 we then varied the $\not\!\! E_{T}$ significance cut  figure of merith used (see Eq. \ref{merit}), we then optimized the $\not\!\! E_{T}$ significance cut.
 \end{enumerate}  \end{enumerate}
   
 For this part of the analysis we present the sets of variables that were taken into account to perform the NN traning  For this part of the analysis we present the sets of variables that were taken into account to perform the NN traning:
 \begin{itemize}  \begin{itemize}
  \item \textit{\textbf{Set I}} : {$H_{T}$},  aplan (aplanarity), sqrts ($\sqrt{s}$)   \item \textit{\textbf{Set 1}} : {$H_{T}$},  aplan (aplanarity), Mjjtau ($M_{jj\tau}$)
  \item \textit{\textbf{Set II}} : {$H_{T}$},  aplan, cent (centrality)   \item \textit{\textbf{Set 2}} : {$H_{T}$},  aplan, cent (centrality)
  \item \textit{\textbf{Set III}} : {$H_{T}$},  aplan, spher (spherecity)   \item \textit{\textbf{Set 3}} : {$H_{T}$},  aplan, spher (spherecity)
  \item \textit{\textbf{Set IV}} : {$H_{T}$}, cent, spher   \item \textit{\textbf{Set 4}} : {$H_{T}$}, cent, spher
  \item \textit{\textbf{Set V}} : aplan, cent, spher   \item \textit{\textbf{Set 5}} : aplan, cent, spher
  \item \textit{\textbf{Set VI}} : {$H_{T}$}, aplan, sqrts, spher   \item \textit{\textbf{Set 6}} : {$H_{T}$}, aplan, Mjjtau, spher
  \item \textit{\textbf{Set VII}} : {$H_{T}$}, aplan, sqrts, cent   \item \textit{\textbf{Set 7}} : {$H_{T}$}, aplan, Mjjtau, cent
  \item \textit{\textbf{Set VIII}} : {$H_{T}$}, aplan, sqrts, costhetastar ($cos(\theta^{*})$   \item \textit{\textbf{Set 8}} : {$H_{T}$}, aplan, Mjjtau, costhetastar ($cos(\theta^{*})$)
  \item \textit{\textbf{Set IX}} : {$H_{T}$}, aplan, sqrts, cent, spher   \item \textit{\textbf{Set 9}} : {$H_{T}$}, aplan, Mjjtau, cent, spher
  \item \textit{\textbf{Set X}} : {$H_{T}$}, aplan, sqrts, cent, costhetastar   \item \textit{\textbf{Set 10}} : {$H_{T}$}, aplan, Mjjtau, cent, costhetastar
  \item \textit{\textbf{Set XI}} : {$H_{T}$}, aplan, sqrts, spher, costhetastar   \item \textit{\textbf{Set 11}} : {$H_{T}$}, aplan, Mjjtau, spher, costhetastar
  \item \textit{\textbf{Set XII}} : metl, {$H_{T}$}, aplan, sqrts   \item \textit{\textbf{Set 12}} : METsig ($\not\!\! E_{T}$ significance), {$H_{T}$}, aplan, Mjjtau
  \item \textit{\textbf{Set XIII}} : metl, {$H_{T}$}, aplan, cent   \item \textit{\textbf{Set 13}} : METsig, {$H_{T}$}, aplan, cent
  \item \textit{\textbf{Set XIV}} : metl, {$H_{T}$}, aplan, spher   \item \textit{\textbf{Set 14}} : METsig, {$H_{T}$}, aplan, spher
  \item \textit{\textbf{Set XV}} : metl, {$H_{T}$}, cent, spher   \item \textit{\textbf{Set 15}} : METsig, {$H_{T}$}, cent, spher
  \item \textit{\textbf{Set XVI}} : metl, {$H_{T}$}, aplan   \item \textit{\textbf{Set 16}} : METsig, {$H_{T}$}, aplan
  \item \textit{\textbf{Set XVII}} : metl, {$H_{T}$}, sqrts   \item \textit{\textbf{Set 17}} : METsig, {$H_{T}$}, Mjjtau
  \item \textit{\textbf{Set XVIII}} : metl, aplan, sqrts   \item \textit{\textbf{Set 18}} : METsig, aplan, Mjjtau
  \item \textit{\textbf{Set XIX}} : metl, {$H_{T}$}, cent   \item \textit{\textbf{Set 19}} : METsig, {$H_{T}$}, cent
  \item \textit{\textbf{Set XX}} : metl, {$H_{T}$}, aplan, sqrts, cent   \item \textit{\textbf{Set 20}} : METsig, {$H_{T}$}, aplan, Mjjtau, cent
  \item \textit{\textbf{Set XXI}} : metl, {$H_{T}$}, aplan, cent, spher   \item \textit{\textbf{Set 21}} : METsig, {$H_{T}$}, aplan, cent, spher
  \item \textit{\textbf{Set XXII}} : metl, {$H_{T}$}, aplan, sqrts, spher   \item \textit{\textbf{Set 22}} : METsig, {$H_{T}$}, aplan, Mjjtau, spher
  \item \textit{\textbf{Set XXIII}} : metl, {$H_{T}$}, aplan, sqrts, costhetastar   \item \textit{\textbf{Set 23}} : METsig, {$H_{T}$}, aplan, Mjjtau, costhetastar
  \item \textit{\textbf{Set XXIV}} : metl, sqrts, cent, spher, costhetastar   \item \textit{\textbf{Set 24}} : METsig, Mjjtau, cent, spher, costhetastar
  \item \textit{\textbf{Set XXV}} : metl, {$H_{T}$}, cent, spher, costhetastar   \item \textit{\textbf{Set 25}} : METsig, {$H_{T}$}, cent, spher, costhetastar
  \item \textit{\textbf{Set XXVI}} : metl, aplan, cent, spher, costhetastar   \item \textit{\textbf{Set 26}} : METsig, aplan, cent, spher, costhetastar
  \item \textit{\textbf{Set XXVII}} : metl, {$H_{T}$}, aplan, cent, costhetastar   \item \textit{\textbf{Set 27}} : METsig, {$H_{T}$}, aplan, cent, costhetastar
  \item \textit{\textbf{Set XXVIII}} : {$H_{T}$}, aplan, topmassl   \item \textit{\textbf{Set 28}} : {$H_{T}$}, aplan, topmassl
  \item \textit{\textbf{Set XXIX}} : {$H_{T}$}, aplan, sqrts, topmassl   \item \textit{\textbf{Set 29}} : {$H_{T}$}, aplan, Mjjtau, topmassl
  \item \textit{\textbf{Set XXX}} : {$H_{T}$}, aplan, sqrts, cent, topmassl   \item \textit{\textbf{Set 30}} : {$H_{T}$}, aplan, Mjjtau, cent, topmassl
  \item \textit{\textbf{Set XXXI}} : {$H_{T}$}, aplan, sqrts, costhetastar, topmassl   \item \textit{\textbf{Set 31}} : {$H_{T}$}, aplan, Mjjtau, costhetastar, topmassl
  \item \textit{\textbf{Set XXXII}} : metl, {$H_{T}$}, topmassl, aplan, sqrts   \item \textit{\textbf{Set 32}} : METsig, {$H_{T}$}, topmassl, aplan, Mjjtau
  \item \textit{\textbf{Set XXXIII}} : metl, spher, costhetastar, aplan, cent   \item \textit{\textbf{Set 33}} : METsig, spher, costhetastar, aplan, cent
 % \item \textit{\textbf{Set XXXIV}} : metl, spher, sqrts, topmassl, ktminp  % \item \textit{\textbf{Set XXXIV}} : metl, spher, Mjjtau, topmassl, ktminp
  \end{itemize}   \end{itemize}
   
   P17 tried only three different sets among hundreds of possible combinations. We believe that the 
   33 sets tested above suffice in giving an optimal result.
 The criteria used for making a decision on which variable should be used follow:  The criteria used for making a decision on which variable should be used follow:
 \begin{itemize}  \begin{itemize}
  \item No more than 5 variables to keep NN simple and stable. More variables leads to instabilities (different    \item No more than 5 variables to keep NN simple and stable. More require larger training samples.
  result after each retraining) and require larger training samples.   \item We want to use METsig variable, since it's the one providing best discrimination.
 % \item We want to use $metl$ (\met significance) variable, since it's the one providing best discrimination.   \item We do not want to use highly correlated variables in same NN. Such as $H_{T}$ and jet $p_{T}$'.
  \item We do not want to use highly correlated variables in same NN.  
 % \item We can not use tau-based variables.   % \item We can not use tau-based variables. 
  \item We want to use variables with high discriminating power.   \item We want to use variables with high discriminating power.
 \end{itemize}  \end{itemize}
   
 In order to make the decision about which of these 11 choices is the optimal we created an ensemble of   In order to make the decision about which of these 33 choices is the optimal we created an ensemble of 
 20000 pseudo-datasets each containing events randomly (according to a Poisson distribution) picked   20000 pseudo-datasets each containing events randomly (according to a Poisson distribution) picked 
 from QCD, EW and $\ttbar$ templates. Each of these datasets was treated like real data, meaning applying all   from QCD, EW and $\ttbar$ templates. Each of these datasets was treated like real data, meaning applying all 
 the cuts and doing the shape fit of event topological NN. QCD templates for fit were made from the same   the cuts and doing the shape fit of event topological NN. QCD templates for fit were made from the same 
 ``loose-tight $\tau$ sample'' from which the QCD component of the ``data'' was drawn.   ``loose-tight $\tau$ sample'' from which the QCD component of the ``data'' was drawn. 
 The figure of merit chosen is given by Equation \ref{merit} below:  We used the folloing quantity as the figure of merit:
   
 \begin{equation}  \begin{equation}
 f = \displaystyle \frac{(N_{fit} - N_{true})}{N_{true}}  f = \displaystyle \frac{(N_{fit} - N_{true})}{N_{true}}
Line 218  f = \displaystyle \frac{(N_{fit} - N_{tr Line 228  f = \displaystyle \frac{(N_{fit} - N_{tr
 \noindent where $N_{fit}$ is the number of $t\bar{t}$ pairs given by   \noindent where $N_{fit}$ is the number of $t\bar{t}$ pairs given by 
 the fit and $N_{true}$ is the number of $t\bar{t}$ pairs from the Poisson distribution.   the fit and $N_{true}$ is the number of $t\bar{t}$ pairs from the Poisson distribution. 
 In both Set and $\not\!\! E_{T}$ significance optimization, the lowest RMS was used   In both Set and $\not\!\! E_{T}$ significance optimization, the lowest RMS was used 
 to caracterize which configuration is the best in each case.  to characterize which configuration is the best in each case.
   
   
 The plots showing results concerning the set optimizations are found in Appendix \ref{app:set_opt} and are summarized   The plots showing results concerning the set optimization are found in Appendix \ref{app:set_opt} and are summarized 
 in Table \ref{setopt_table} below, where each RMS and mean are shown.  in Table \ref{setopt_table} below, where each RMS and mean are shown. The parenthesis after each set ID show the number of 
 For NN training is standard to choose the number of hidden nodes as being twice   
 the number the number of variables used for the training. The parenthesis after each set ID show the number of   
 hidden nodes in NN training.  hidden nodes in NN training.
   
 \begin{table}[htbp]  \begin{table}[htbp]
Line 307  The number in parenthesis refers to numb Line 315  The number in parenthesis refers to numb
 \label{setopt_table}   \label{setopt_table} 
 \end{table}  \end{table}
   
 From Table \ref{setopt_table} we see that Set I has the lowest RMS, thus we chose it  From Table \ref{setopt_table} we see that Set 32 has the lowest RMS, thus we chose it
 as the set to be used in $\not\!\! E_{T}$ significance optimization part, whose results are  as the set to be used in $\not\!\! E_{T}$ significance optimization part, whose results are
 shown in Appendix \ref{app:metl_opt} and then summarized in Table \ref{metlopt_table} below  shown in Appendix \ref{app:metl_opt} and then summarized in Table \ref{metlopt_table} below
   
 \begin{table}[htbp]  \begin{table}[htbp]
 \begin{tabular}{|c|r|r|r|} \hline  \begin{tabular}{|c|r|r|r|r|} \hline
 Set of variables  & $\not\!\! E_{T}$ significance cut & RMS    & \multicolumn{1}{c|}{mean} \\ \hline  Set 32  & Number of hidden nodes &$\not\!\! E_{T}$ significance cut & RMS    & \multicolumn{1}{c|}{mean} \\ \hline
   
 \hline  \hline
   
Line 326  Set of variables  & $\not\!\! E_{T}$ sig Line 334  Set of variables  & $\not\!\! E_{T}$ sig
   
 %Set6(10)      &  \multicolumn{1}{c|}{2.5} &  \multicolumn{1}{c|}{0.2021}   \\ \hline  %Set6(10)      &  \multicolumn{1}{c|}{2.5} &  \multicolumn{1}{c|}{0.2021}   \\ \hline
   
 Set32(10)      &  \multicolumn{1}{c|}{3.0} &  \multicolumn{1}{c|}{0.1507}   &  \multicolumn{1}{c|}{0.0157}\\ \hline  1     &  \multicolumn{1}{c|}{10} &  \multicolumn{1}{c|}{3.0} &  \multicolumn{1}{c|}{0.1507}   &  \multicolumn{1}{c|}{0.0157}\\ \hline
   
 Set32(10)      &  \multicolumn{1}{c|}{3.5} &  \multicolumn{1}{c|}{0.1559}   &  \multicolumn{1}{c|}{0.0189}\\ \hline  2      &  \multicolumn{1}{c|}{10} &  \multicolumn{1}{c|}{3.5} &  \multicolumn{1}{c|}{0.1559}   &  \multicolumn{1}{c|}{0.0189}\\ \hline
   
 Set32(10)     &  \multicolumn{1}{c|}{4.0} &  \multicolumn{1}{c|}{0.1468}   &  \multicolumn{1}{c|}{0.0172}\\ \hline  3     &  \multicolumn{1}{c|}{10} &  \multicolumn{1}{c|}{4.0} &  \multicolumn{1}{c|}{0.1468}   &  \multicolumn{1}{c|}{0.0172}\\ \hline
   
 Set32(10)     &  \multicolumn{1}{c|}{4.5} &  \multicolumn{1}{c|}{0.1511}   &  \multicolumn{1}{c|}{0.0153}\\ \hline  4     &  \multicolumn{1}{c|}{10} &  \multicolumn{1}{c|}{4.5} &  \multicolumn{1}{c|}{0.1511}   &  \multicolumn{1}{c|}{0.0153}\\ \hline
   
 Set32(10)     &  \multicolumn{1}{c|}{5.0} &  \multicolumn{1}{c|}{0.1552}   &  \multicolumn{1}{c|}{0.0205}\\ \hline  5     &  \multicolumn{1}{c|}{10} &  \multicolumn{1}{c|}{5.0} &  \multicolumn{1}{c|}{0.1552}   &  \multicolumn{1}{c|}{0.0205}\\ \hline
   
 %Set6(10)     &  \multicolumn{1}{c|}{5.5} &  \multicolumn{1}{c|}{0.4008}   \\ \hline  %Set6(10)     &  \multicolumn{1}{c|}{5.5} &  \multicolumn{1}{c|}{0.4008}   \\ \hline
 \end{tabular}  \end{tabular}
Line 346  The number in parenthesis refers to numb Line 354  The number in parenthesis refers to numb
   
   
 Combined results from Tables \ref{setopt_table} and \ref{metlopt_table} show that the best configuration found  Combined results from Tables \ref{setopt_table} and \ref{metlopt_table} show that the best configuration found
 was Set I  with $\not\!\! E_{T}$ significance $\geq$ 4.0. Therefore, this was the   was Set 32  with $\not\!\! E_{T}$ significance $\geq$ 4.0. Therefore, this was the 
 configuration used to perform the cross-section measurement.Figure \ref{fig:METsig_RMS} shows the variation of the RMS as function   configuration used to perform the cross section measurement.Figure \ref{fig:METsig_RMS} shows the variation of the RMS as function 
 of the $\not\!\! E_{T}$ significance we applied.  of the $\not\!\! E_{T}$ significance we applied.
   
 \begin{figure}[b]  \begin{figure}[h]
 \includegraphics[scale=0.4]{plots/METsig-RMS.eps}  \includegraphics[scale=0.35]{plots/METsig-RMS.eps}
 \caption{Plot of RMS as a function the $\not\!\! E_{T}$ significance applied}  \caption{Plot of RMS as a function the $\not\!\! E_{T}$ significance applied}
 \label{fig:METsig_RMS}  \label{fig:METsig_RMS}
 \end{figure}  \end{figure}
   
   
 \clearpage  %\clearpage
   
   
 In order to check the validity of our emsemble tests procedure, it is instructive to plot both the   In order to check the validity of our emsemble tests procedure, it is instructive to plot both the 
Line 378  initially set in the ensemble and the me Line 386  initially set in the ensemble and the me
 curve, that indicates a good behaviour of the fit uncertainties in the ensembles.  curve, that indicates a good behaviour of the fit uncertainties in the ensembles.
   
 \begin{figure}[t]  \begin{figure}[t]
 \includegraphics[scale=0.5]{plots/gaus_ttbar.eps}  \includegraphics[scale=0.40]{plots/gaus_ttbar.eps}
 \caption{Distribution of the output ``measurement'' for an ensemble with 116.9 $\ttbar$ events.}  \caption{Distribution of the output ``measurement'' for an ensemble with 116.9 $\ttbar$ events.}
 \label{fig:gaus_ttbar}  \label{fig:gaus_ttbar}
 \end{figure}  \end{figure}
   
 \begin{figure}[t]  \begin{figure}[b]
 \includegraphics[scale=0.5]{plots/pull1-40.eps}  \includegraphics[scale=0.40]{plots/pull1-40.eps}
 \caption{The ensemble test's pull.}  \caption{The ensemble test's pull.}
 \label{fig:pull}  \label{fig:pull}
 \end{figure}  \end{figure}

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