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vuko |
1.1 |
\section{Event reconstruction}
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\label{sec:eventReconstruction}
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ymaravin |
1.12 |
We categorize \WZ\ three-lepton final state as following
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vuko |
1.2 |
\begin{itemize}
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\item $3e$: for \WZ events with $\W \to e \nu$ and $\Z\to \epem$.
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\item $2e1\mu$: for \WZ events with $\W \to \mu \nu$ and $\Z\to \epem$.
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\item $2\mu 1e$: for \WZ events with $\W \to e \nu$ and $\Z\to \mumu$.
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\item $3\mu$: for \WZ events with $\W \to \mu \nu$ and $\Z\to \mumu$.
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\end{itemize}
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vuko |
1.1 |
\subsection{Trigger selection and efficiencies}
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vuko |
1.2 |
Events stemming from the three-lepton final states of $\WZ$ production
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beaucero |
1.4 |
are collected by the electron and/or muon triggers. For each channel,
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vuko |
1.2 |
a minimun number of HLT requirements is chosen while keeping
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the HLT efficiency for selected events close to 100\%. The same
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ymaravin |
1.12 |
HLT requirements are used for channels with the same \Z decay mode:
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vuko |
1.2 |
\begin{itemize}
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\item for $3e$ and $2e1\mu$: HLTSingleElectron or HLTDoubleElectronRelaxed
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\item for $2\mu1e$ and $3\mu$: HLTSingleMuonIso
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\end{itemize}
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The HLT efficiencies for all modes for events passing the full
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selection described in this section are given in table~\ref{tab:hlteff}.
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\begin{table}[tbph]
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\begin{center}
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\begin{tabular}{llc} \hline \hline
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Channel & HLT selection & HLT efficiency \\ \hline
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$3e$ & HLTSingleElectron or HLTDoubleElectronRelaxed & 0.996 \\
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$2e1\mu$ & HLTSingleElectron or HLTDoubleElectronRelaxed & 0.969 \\
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$2\mu 1e$ & HLTSingleMuonIso & 0.966 \\
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$3\mu$ & HLTSingleMuonIso & 0.994 \\ \hline \hline
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\end{tabular}
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\end{center}
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vuko |
1.15 |
\caption{HLT Efficiencies for all the events in the generated phase space that
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have been retained by the complete event selection.}
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vuko |
1.2 |
\label{tab:hlteff}
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\end{table}
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vuko |
1.1 |
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vuko |
1.10 |
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\begin{figure}[tbp]
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\begin{center}
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\scalebox{0.7}{\includegraphics{figs/mu_isol.eps}}
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\caption{Muon isolation variables for the muon associated
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ymaravin |
1.12 |
to the \W boson decay in $2e1\mu$ events: in the left plot
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we illustrate the sum of calorimetric energy in a $\Delta R=0.3$ cone
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around the muon candidate; in the right plot we display the sum of
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vuko |
1.10 |
transverse momenta of tracks within a $\Delta R = 0.25$ cone around
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the muon candidate. The normalization of signal and background
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distributions is arbitrary.
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}
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\label{fig:mu_isol}
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\end{center}
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\end{figure}
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\begin{figure}[tb]
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\begin{center}
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\scalebox{0.6}{\includegraphics{figs/mu_SIP.eps}}
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\caption{
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Muon impact parameter significance distribution
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in $2e1\mu$ events. The normalization of signal and background
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distributions is arbitrary.
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}
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\label{fig:mu_SIP}
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\end{center}
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\end{figure}
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vuko |
1.1 |
\subsection{Lepton identification}
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vuko |
1.2 |
\label{sec:leptonId}
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vuko |
1.1 |
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vuko |
1.2 |
The requirements used for electron identification in this analysis are described
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in~\cite{noteElectronID}.
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Muon candidates are selected from global muons, which are reconstructed
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ymaravin |
1.12 |
by combining measurements in the muon chambers and the central tracker.
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An additional isolation criterion is imposed to require the energy
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vuko |
1.2 |
measured in the calorimeters within a $\Delta R = 0.3$ cone around the
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ymaravin |
1.12 |
muon to be smaller than 3 GeV and the sum of the $p_T$ of tracks
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within a $\Delta R = 0.25$ cone around the muon must be smaller than 2 GeV.
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vuko |
1.7 |
These cuts reduce the background from muons originated in
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vuko |
1.2 |
\b-quark decays of the $\Zbbbar$ background, which are close to tracks
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and clusters from the other \b-quark decay products.
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vuko |
1.16 |
The signal and background distributions of these isolation variables
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are shown in Figure~\ref{fig:mu_isol} for the muon in $2e1\mu$ candidate
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events.
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vuko |
1.2 |
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%Figures~\ref{fig:muonisol} and ~\ref{fig:muonisoleffi} show the
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%performance of the isolation cut. The distribution of the isolation
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%variables for the $\Z\b\bbar(\epem\b\bbar)$ is particularly
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%interesting, since muons only stem from \b-quark decays.
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vuko |
1.1 |
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vuko |
1.3 |
The significance of the muon impact parameter in the plane
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transverse to the beam, $S_{IP}$, discriminates against leptons from
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ymaravin |
1.12 |
heavy-quark decays in all standard model background processes. This
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vuko |
1.3 |
variable is defined as the ratio between the measured impact parameter
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and its uncertainty: $S_{IP}=IP/\sigma_{IP}$, and is required to
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ymaravin |
1.12 |
satisfy $S_{IP}<3$. This requirement is applied only for muon candidates
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and not for electrons. For electron candidates, a significant fraction of the
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background comes from misidentified light quark jets. Thus,
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the requirement on the impact parameter significance does not
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increase the significance of the $\W\to e$ channels, as can be seen in
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vuko |
1.16 |
Fig.~\ref{fig:wl_IP_SvsCut}. The distribution of $S_{IP}$ for the muon
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in $2e1\mu$ candidate events is shown in Figure~\ref{fig:mu_SIP}.
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vuko |
1.3 |
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vuko |
1.10 |
\begin{figure}[p]
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\begin{center}
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\scalebox{0.6}{\includegraphics{figs/wl_IP_eff.eps}}
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\caption{Efficiency for signal and background as a function
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ymaravin |
1.12 |
of the requirement on the \W-boson lepton impact parameter
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significance. All other criteria but the one on impact parameter
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significance are applied.
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vuko |
1.15 |
% Only events with 81 GeV $< M_Z < $ 101 \gev
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vuko |
1.10 |
% are considered.
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}
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\label{fig:wl_IP_eff}
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\end{center}
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%\end{figure}
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%\begin{figure}[bt]
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\begin{center}
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\scalebox{0.6}{\includegraphics{figs/wl_IP_SvsCut.eps}}
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ymaravin |
1.12 |
\caption{Signal significance as a function of requirement on
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the \W-boson lepton impact parameter significance. All other criteria but
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the requirement on the impact parameter significance are applied.
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vuko |
1.15 |
% Only events with 81 GeV $< M_Z < $ 101 \gev are considered.
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vuko |
1.10 |
}
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\label{fig:wl_IP_SvsCut}
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\end{center}
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\end{figure}
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vuko |
1.3 |
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vuko |
1.1 |
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vuko |
1.7 |
\begin{table}[tbp]
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\begin{tabular}{|l|c|c|c|c|} \hline
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& $3e$ & $2e1\mu$ & $2\mu 1e$ & $3\mu$ \\ \hline \hline
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\multicolumn{5}{|c|}{Lepton selection} \\ \hline
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ymaravin |
1.13 |
Electrons & \multicolumn{3}{|c|}{{\tt SimpleLoose} requirements for \Z reconstruction} & \\
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& \multicolumn{3}{|c|}{{\tt SimpleTight} requirements for \W} & \\ \hline
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vuko |
1.7 |
Muons & & \multicolumn{3}{|c|}{ Track Isolation:$ {\tt IsoTrack}(\Delta R= 0.25) < 2 \gev$} \\
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& & \multicolumn{3}{|c|}{ Calorimetric Isolation:$ {\tt IsoCalo}(\Delta R = 0.3) < 5 \gev$} \\
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& & \multicolumn{3}{|c|}{$S_{IP}=IP/\sigma_{IP}<3$ } \\ \hline
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HLT requirement & \multicolumn{2}{|c|}{ HLTSingleElectron or HLTDoubleElectronRelaxed}
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& \multicolumn{2}{|c|}{ HLTSingleMuonIso} \\ \hline
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| 148 |
ymaravin |
1.13 |
\multicolumn{5}{|c|}{\Z reconstruction} \\ \hline
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Lepton cuts & \multicolumn{4}{|c|}{for both \Z leptons: $p_T > 15$ GeV} \\
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vuko |
1.7 |
Mass window & \multicolumn{4}{|c|}{$50 \gev < M_Z < 120 \gev $ } \\
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ymaravin |
1.13 |
Second \Z veto & \multicolumn{4}{|c|}{No independent second \Z candidate with $50 \gev < M_Z < 120 \gev $ } \\ \hline
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\multicolumn{5}{|c|}{\W lepton selection} \\ \hline
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| 153 |
vuko |
1.7 |
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Other cuts & & & $\Delta R(\mu_Z,e_W)>0.1$ & \\ \hline
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Signal region & \multicolumn{4}{|c|}{$81 \gev < M_Z < 101 \gev $ } \\ \hline \hline
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\end{tabular}
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ymaravin |
1.13 |
\caption{Summary of the criteria we use to select \WZ\ final state}
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vuko |
1.7 |
\label{tab:allcuts}
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\end{table}
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\begin{figure}[p]
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\begin{center}
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| 165 |
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\scalebox{0.6}{\includegraphics{figs/wlpt_cuteff.eps}}
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\caption{Efficiency for signal and background as a function
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of the cut value on the \W-boson lepton transverse momentum.
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All other cuts but the cut on this variable are applied.
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| 169 |
vuko |
1.15 |
Only events with 81 GeV $< M_Z < $ 101 \gev
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| 170 |
vuko |
1.7 |
are considered.}
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\label{fig:wlpt_cuteff}
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\end{center}
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%\end{figure}
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| 175 |
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%\begin{figure}[bt]
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\begin{center}
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| 177 |
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\scalebox{0.6}{\includegraphics{figs/wlpt_cutS.eps}}
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| 178 |
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\caption{Signal significance as a function of the cut value on
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| 179 |
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the \W-boson lepton transverse momentum. All other cuts but
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| 180 |
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the cut on this variable are applied. Only events with
|
| 181 |
vuko |
1.15 |
81 GeV $< M_Z < $ 101 \gev are considered.}
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| 182 |
vuko |
1.7 |
\label{fig:wlpt_cutS}
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| 183 |
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\end{center}
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\end{figure}
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vuko |
1.1 |
\subsection{\WZ candidate selection}
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| 189 |
vuko |
1.2 |
Events are accepted if they contain at least three charged leptons,
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| 190 |
ymaravin |
1.13 |
either electrons or muons, with $p_T > 15\,\mathrm{GeV}$ and $| \eta | < 2.5$ for
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| 191 |
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electrons,$| \eta | < 2.4$ for muons, as discussed in Section~\ref{sec:leptonId}.
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| 192 |
vuko |
1.2 |
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| 193 |
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The \WZ candidate selection proceeds from building all possible
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| 194 |
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\Z-boson candidates from same-flavour opposite-charge lepton pairs.
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| 195 |
ymaravin |
1.13 |
For $\Z \to ee$ decays, electron candidates have to fulfill the loose requirements
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| 196 |
vuko |
1.2 |
defined in~\cite{noteElectronID}.
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|
| 198 |
ymaravin |
1.13 |
Events are retained if the mass of the \Z boson candidate is
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| 199 |
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within 20 GeV of the \Z boson mass, $m_Z$. The event is
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| 200 |
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rejected if a second \Z candidate is found. This second \Z boson candidate is formed
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| 201 |
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using all possible same-flavour opposite-charge combinations which are left
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after removing the two leptons already used for the first \Z boson candidate. This
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| 203 |
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secondary \Z boson veto helps to suppress $\Z\Z$ events.
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vuko |
1.11 |
%The invariant
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%mass distribution for accepted \Z candidates is shown in
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| 206 |
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%Figure~\ref{fig:zcandidates}.
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vuko |
1.2 |
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| 208 |
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% and the \Z mass resolution is shown in
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| 209 |
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%Figure~\ref{fig:dzmass}.
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|
| 211 |
ymaravin |
1.13 |
After the \Z boson candidate is identified, the remaining leptons in the event
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| 212 |
vuko |
1.15 |
are required, for electrons, to pass the tight criteria described in~\cite{noteElectronID}
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or, for muons, all criteria described in section~\ref{sec:leptonId}.
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| 214 |
ymaravin |
1.13 |
If more than one lepton candidate satisfies the tight requirements, the one with the
|
| 215 |
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highest $p_T$ is associated with \W boson decay. This lepton's $p_T$ is effective
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discriminant against \Zbbbar and \Zjets production (see Fig.~\ref{fig:wlpt_cuteff}).
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| 217 |
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We require the transverse momentum to exceed 20 GeV, as it maximizes
|
| 218 |
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the significance of the \WZ\ signal with respect to background as shown in
|
| 219 |
vuko |
1.15 |
Fig.~\ref{fig:wlpt_cutS}.
|
| 220 |
ymaravin |
1.13 |
|
| 221 |
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An additional requirement on the isolation between electron and muon candidates is applied
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| 222 |
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for the $2\mu 1e$ channel, by demanding the value of $\Delta R$ between the electron
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| 223 |
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candidate associated with the \W boson decay and any of the two muons associated with
|
| 224 |
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the \Z boson decay to be greater than 0.1.
|
| 225 |
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|
| 226 |
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This requirement allows suppressing the contribution of $\Z \to \mu\mu$
|
| 227 |
vuko |
1.6 |
decays, where one of the two muons radiates a photon which is reconstructed
|
| 228 |
ymaravin |
1.13 |
as an electron, possibly after conversion. This can be seen as a peak in the dimuon
|
| 229 |
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invariant mass at around 60 GeV in Fig.~\ref{fig:Z2mu1e_60GeVPeak}.
|
| 230 |
vuko |
1.6 |
|
| 231 |
ymaravin |
1.13 |
The summary of the selection criteria is given in Table~\ref{tab:allcuts}.
|
| 232 |
vuko |
1.7 |
|
| 233 |
ymaravin |
1.13 |
The expected number of the events satisfying the sequential steps of the selection
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| 234 |
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is listed in Tables~\ref{tab:sel-effA}.
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| 235 |
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In Table~\ref{tab:wz-effimatrix} we list the total selection efficiency for different
|
| 236 |
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\W and \Z boson decay modes. It can be seen lepton candidates from \W and \Z
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| 237 |
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boson decays are almost always are reconstructed with the correct flavor. As expected,
|
| 238 |
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there is a small contribution from $\W \to \tau \nu_\tau \to \ell \nu_\ell \nu_\tau$
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| 239 |
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decays. However, this contribution is suppressed, mostly due to $p_T$ requirement
|
| 240 |
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on the third lepton, as leptons from $\tau$ decays are not as energetic as those from
|
| 241 |
|
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$\W \to \ell \nu$ processes.
|
| 242 |
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|
| 243 |
vuko |
1.15 |
In Tables~\ref{tab:wz-matcheffi-Zee} and \ref{tab:wz-matcheffi-Zmumu} we
|
| 244 |
ymaravin |
1.13 |
display the fraction of reconstructed \WZ events with correctly-matched leptons.
|
| 245 |
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It can be seen that the lepton associated with the \W boson decay is correctly matched
|
| 246 |
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to the true Monte Carlo lepton from the \W boson decay in more than 90\% of
|
| 247 |
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the cases, even for events with several lepton candidates available to be associated
|
| 248 |
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to the \W boson decay. The choice to take the lepton candidate with the leading $p_T$ is,
|
| 249 |
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therefore, justified.
|
| 250 |
vuko |
1.11 |
|
| 251 |
vuko |
1.3 |
\begin{table}[p]
|
| 252 |
|
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\begin{center}
|
| 253 |
|
|
|
| 254 |
vuko |
1.9 |
|
| 255 |
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|
| 256 |
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|
| 257 |
ymaravin |
1.13 |
\begin{tabular}{lcc|cc|cc|cc|c} \hline \hline
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| 258 |
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\multicolumn{9}{c}{ {\bf $3e$ Channel}} \\ \hline \hline
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| 259 |
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Step & \WZ & $\epsilon$ & $b\bar{b}\ell\ell$ & $\epsilon$ & $\Z+jets$ & $\epsilon$ & $t\bar{t}+jets$ & $\epsilon$ \\ \hline
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| 260 |
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All events & 546 & & 72,700 & & 1,268,000 & & 17,600 & \\
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| 261 |
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Found $\Z \to ee$ & 205 & 38\% & 27,800 & 38\% & 502,300 & 40\% & 2,920 & 17\% \\
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| 262 |
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Found $\W \to e\nu$ & 42.0 & 21\% & 171 & 0.6\% & 309.6 & 0.06\% & 13.8 & 0.5\% \\
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\W lepton $p_T$ cut & 34.9 & 83\% & 23.7 & 14\% & 86.8 & 28 \% & 8.3 & 60\% \\
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| 264 |
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Passes HLT & 34.7 & 100\% & 23.6 & 99\% & 86.8 &100\% & 8.3 & 100\% \\
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| 265 |
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\Z mass window & 31.6 & 91\% & 17.5 & 74\% & 51.9 &60\% & 3.3 & 39\% \\ \hline
|
| 266 |
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Overall efficiency & & 5.8\% & & 0.024\% & & 0.0041\% & & 0.019\% \\
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\hline\hline
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|
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\multicolumn{9}{c}{ {\bf $2e1\mu$ Channel}} \\ \hline \hline
|
| 270 |
|
|
Step & \WZ & $\epsilon$ & $b\bar{b}\ell\ell$ & $\epsilon$ & $\Z+jets$ & $\epsilon$ & $t\bar{t}+jets$ & $\epsilon$ \\ \hline
|
| 271 |
|
|
All events & 546 & & 72,770 & & 1,268,000 & & 17,600 & \\
|
| 272 |
|
|
Found $\Z \to ee$ & 201 & 38\% & 27,800 & 38\% & 502,300 & 40\% & 2,921 &17\% \\
|
| 273 |
|
|
Found $\W \to \mu\nu$ & 47.9 & 23\% & 748 & 2.7\% & 2194 & 0.43\% & 56.8 &1.9\% \\
|
| 274 |
|
|
\W lepton $p_T$ cut & 37.1 & 77\% & 9.6 & 1.3\% & 9.6 & 0.4\% & 17.5 &31\% \\
|
| 275 |
|
|
Passes HLT & 36.2 & 98\% & 9.3 & 96\% & 8.3 & 87\% & 15.2 & 87 \%) \\
|
| 276 |
|
|
\Z mass window & 32.5 & 90\% & 8.2 & 88\% & 7.3 & 88\% & 4.9 & 32\%) \\ \hline
|
| 277 |
|
|
Overall efficiency & & 6.0\% & & 0.011\% & & 0.00058\% & & 0.028\% \\
|
| 278 |
|
|
\hline \hline
|
| 279 |
|
|
|
| 280 |
|
|
\multicolumn{9}{c}{ {\bf $2\mu1e$ Channel}} \\ \hline \hline
|
| 281 |
|
|
Step & \WZ & $\epsilon$ & $b\bar{b}\ell\ell$ & $\epsilon$ & $\Z+jets$ & $\epsilon$ & $t\bar{t}+jets$ & $\epsilon$ \\ \hline
|
| 282 |
|
|
All events & 546 & & 72,770 & & 1,268,000 & & 17,600 & \\
|
| 283 |
|
|
Found $\Z \to \mu\mu$ & 234 &43\%& 31,890 & 44\% & 577,200 & 46\% & 2779 & 16\% \\
|
| 284 |
|
|
Found $\W \to e\nu$ & 48.8 &21\%& 214 & 0.67\% & 702 & 0.12\% & 15.1 & 0.54\% \\
|
| 285 |
|
|
\W lepton $p_T$ cut & 40.7 &83\%& 50.6 & 24\% & 464.0 & 66\% & 10.3 & 68\% \\
|
| 286 |
|
|
$\Delta R(e,\mu)$ cut & 40.6&100\%& 23.3 & 46\% & 93.0 & 20\% & 7.1 & 70\% \\
|
| 287 |
|
|
Passes HLT & 39.4 &97\%& 23.2 & 99\% & 88.8 & 95\% & 6.6 & 93\% \\
|
| 288 |
|
|
\Z mass window & 35.6 & 90\% & 18.9 & 81\% & 50.3 & 57\% & 2.8 &44\% \\ \hline
|
| 289 |
|
|
Overall efficiency & &6.5\% & & 0.026\% & & 0.0040\% & & 0.016\% \\
|
| 290 |
|
|
\hline \hline
|
| 291 |
|
|
|
| 292 |
|
|
\multicolumn{9}{c}{ {\bf $3\mu$ Channel}} \\ \hline \hline
|
| 293 |
|
|
Step & \WZ & $\epsilon$ & ${b\bar{b}\ell\ell}$ & $\epsilon$ & $\Z+jets$ & $\epsilon$ & ${t\bar{t}+jets}$ & $\epsilon$ \\ \hline
|
| 294 |
|
|
All events & 546 & & 72,770 & & 1,268,000 & & 17,600 & \\
|
| 295 |
|
|
Found $Z \to \mu\mu$ & 234 & 43\% & 31,900 & 44\% & 577,000 & 45\% & 2779 & 16 \% \\
|
| 296 |
|
|
Found $W \to \mu$ & 58 & 25 \% & 811 & 2.5\% & 2521 & 0.44\% & 35.3 & 1.23 \% \\
|
| 297 |
|
|
W Lepton Pt cut & 44.2 & 77 \% & 8.9 & 1.1\% & 1.8 & 0.07\% & 1.7 & 4.8 \% \\
|
| 298 |
|
|
Passes HLT & 44.0 & 99\% & 8.9 & 100\% & 1.8 & 100 \% & 1.7 & 100 \% \\
|
| 299 |
|
|
Z mass window & 40.0 & 91 \%) & 7.8 & 88\% & 1.8 & 100 \% & 1.2 & 69\% \\ \hline
|
| 300 |
|
|
Overall efficiency & & 7.3 \% & & 0.011\% & & 0.00015\% & & 0.0065\% \\
|
| 301 |
vuko |
1.3 |
\hline
|
| 302 |
|
|
\end{tabular}
|
| 303 |
vuko |
1.9 |
|
| 304 |
|
|
|
| 305 |
vuko |
1.3 |
\caption{Expected number of signal and background events passing the different
|
| 306 |
ymaravin |
1.13 |
selections steps together with the efficiency of each requirement and total efficiency of
|
| 307 |
|
|
selection criteria in the \WZ, \Zbbbar, \Zjets and \ttjets samples for an integrated luminosity
|
| 308 |
vuko |
1.3 |
of 1 \invfb.}
|
| 309 |
|
|
\label{tab:sel-effA}
|
| 310 |
|
|
\end{center}
|
| 311 |
|
|
\end{table}
|
| 312 |
|
|
|
| 313 |
vuko |
1.11 |
\begin{table}[p]
|
| 314 |
vuko |
1.7 |
\begin{center}
|
| 315 |
ymaravin |
1.13 |
\begin{tabular}{l|ccccc}
|
| 316 |
vuko |
1.7 |
\hline \hline
|
| 317 |
ymaravin |
1.13 |
& \multicolumn{5}{c}{$\Z \to ee$ and \W decay modes below} \\
|
| 318 |
|
|
Reconstruction channel & $e \nu$
|
| 319 |
|
|
& $\mu \nu $
|
| 320 |
|
|
& $\tau \nu \to e \nu \nu $
|
| 321 |
|
|
& $\tau \nu \to \mu \nu \nu $
|
| 322 |
|
|
& $\tau \nu \to {\rm hadrons~} \nu$
|
| 323 |
vuko |
1.7 |
\\ \hline
|
| 324 |
|
|
$3e$ & 17.4 \% & 0.0319 \% & 6.42 \% & 0 \% & 0.162 \% \\
|
| 325 |
|
|
$2e1\mu$ & 0 \% & 18.6 \% & 0 \% & 5.53 \% & 0.0485 \% \\
|
| 326 |
|
|
$2\mu1e$ & 0 \% & 0 \% & 0 \% & 0 \% & 0 \% \\
|
| 327 |
|
|
$3\mu$ & 0 \% & 0 \% & 0 \% & 0 \% & 0 \% \\
|
| 328 |
|
|
\hline \hline
|
| 329 |
ymaravin |
1.13 |
|
| 330 |
|
|
& \multicolumn{5}{c}{$\Z \to \mu\mu$ and \W decay modes below} \\
|
| 331 |
|
|
Reconstruction channel & $e\nu$
|
| 332 |
|
|
& $\mu\nu$
|
| 333 |
|
|
& $\tau\nu \to e\nu\nu$
|
| 334 |
|
|
& $\tau\nu \to \mu\nu\nu$
|
| 335 |
|
|
& $\tau\nu \to {\rm hadrons~}\nu$
|
| 336 |
vuko |
1.7 |
\\ \hline
|
| 337 |
|
|
$3e$ & 0 \% & 0 \% & 0 \% & 0 \% & 0 \% \\
|
| 338 |
|
|
$2e1\mu$ & 0.0104 \% & 0 \% & 0 \% & 0 \% & 0 \% \\
|
| 339 |
|
|
$2\mu1e$ & 19.6 \% & 0.0208 \% & 5.56 \% & 0 \% & 0.18 \% \\
|
| 340 |
|
|
$3\mu$ & 0 \% & 23.4 \% & 0.0573 \% & 6.77 \% & 0.0164 \% \\
|
| 341 |
|
|
\hline \hline
|
| 342 |
|
|
\end{tabular}
|
| 343 |
|
|
\end{center}
|
| 344 |
|
|
\caption{Selection efficiency for signal events in the four selection channels for the different
|
| 345 |
|
|
generated \W and \Z decay channels.}
|
| 346 |
|
|
\label{tab:wz-effimatrix}
|
| 347 |
|
|
|
| 348 |
vuko |
1.11 |
%\end{table}
|
| 349 |
|
|
%\begin{table}[tbp]
|
| 350 |
vuko |
1.7 |
\begin{center}
|
| 351 |
|
|
\begin{tabular}{llcc} \hline
|
| 352 |
ymaravin |
1.13 |
& & \multicolumn{2}{c}{Generated decay} \\
|
| 353 |
|
|
& & \multicolumn{2}{c}{$\Z \to ee $} \\
|
| 354 |
|
|
Selection channel & & $\W \to e\nu$ & $\W \to \mu\nu$ \\
|
| 355 |
vuko |
1.7 |
\hline \hline
|
| 356 |
|
|
\multicolumn{4}{c}{all} \\ \hline
|
| 357 |
ymaravin |
1.13 |
$3e$ & all & 1644 events & 3 events \\
|
| 358 |
|
|
$3e$ & matched \Z & 93$\pm$1\% & 100\%\\
|
| 359 |
|
|
$3e$ & matched \W & 92$\pm$1\% & 0\\
|
| 360 |
|
|
$3e$ & matched \WZ & 91$\pm$1\% & 0\\
|
| 361 |
|
|
\hline \hline
|
| 362 |
|
|
|
| 363 |
|
|
\multicolumn{4}{c}{exactly 1 \W lepton candidate} \\ \hline
|
| 364 |
|
|
$3e$ & all & 1602 events & 0 events \\
|
| 365 |
|
|
$3e$ & matched \Z & 94$\pm$1\% & 0\\
|
| 366 |
|
|
$3e$ & matched \W & 92$\pm$1\% & 0\\
|
| 367 |
|
|
$3e$ & matched \WZ & 91$\pm$1\% & 0\\
|
| 368 |
|
|
\hline \hline
|
| 369 |
|
|
|
| 370 |
|
|
\multicolumn{4}{c}{more than 1 \W lepton candidate} \\ \hline
|
| 371 |
|
|
$3e$ & all & 42 events & 3 events \\
|
| 372 |
|
|
$3e$ & matched \Z & 93$\pm$4\% & 100\%\\
|
| 373 |
|
|
$3e$ & matched \W & 91 $\pm$5\% & 0\\
|
| 374 |
|
|
$3e$ & matched \WZ & 91$\pm$5\% & 0\\
|
| 375 |
vuko |
1.7 |
\hline \hline
|
| 376 |
ymaravin |
1.13 |
|
| 377 |
vuko |
1.7 |
\multicolumn{4}{c}{all} \\ \hline
|
| 378 |
ymaravin |
1.13 |
$2e1\mu$ & all & 0 events & 1746 events \\
|
| 379 |
|
|
$2e1\mu$ & matched \Z & 0 & 100\%\\
|
| 380 |
|
|
$2e1\mu$ & matched \W & 0 & 100\%\\
|
| 381 |
|
|
$2e1\mu$ & matched \WZ & 0 & 100\%\\
|
| 382 |
|
|
\hline \hline
|
| 383 |
|
|
|
| 384 |
|
|
\multicolumn{4}{c}{exactly 1 \W lepton candidate} \\ \hline
|
| 385 |
|
|
$2e1\mu$ & all & 0 events & 1715 events \\
|
| 386 |
|
|
$2e1\mu$ & matched \Z & 0 & 100\%\\
|
| 387 |
|
|
$2e1\mu$ & matched \W & 0 & 100\%\\
|
| 388 |
|
|
$2e1\mu$ & matched \WZ & 0 & 100\%\\
|
| 389 |
vuko |
1.7 |
\hline \hline
|
| 390 |
ymaravin |
1.13 |
|
| 391 |
|
|
\multicolumn{4}{c}{more than 1 \W lepton candidate} \\ \hline
|
| 392 |
vuko |
1.7 |
$2e1\mu$ & all & 0 & 31 \\
|
| 393 |
ymaravin |
1.13 |
$2e1\mu$ & matched \Z & 0 & 100\%\\
|
| 394 |
|
|
$2e1\mu$ & matched \W & 0 & 100\%\\
|
| 395 |
|
|
$2e1\mu$ & matched \WZ & 0 & 100\% \\ \hline \hline
|
| 396 |
vuko |
1.7 |
\end{tabular}
|
| 397 |
|
|
\end{center}
|
| 398 |
|
|
\caption{Fractions of events with correctly matched leptons
|
| 399 |
|
|
to true decay product of \W and \Z decays for final states
|
| 400 |
|
|
with generated $\Z\to ee$ decays}
|
| 401 |
|
|
\label{tab:wz-matcheffi-Zee}
|
| 402 |
|
|
\end{table}
|
| 403 |
|
|
|
| 404 |
|
|
|
| 405 |
|
|
|
| 406 |
|
|
\begin{table}[tbp]
|
| 407 |
|
|
\begin{center}
|
| 408 |
|
|
\begin{tabular}{llcc} \hline
|
| 409 |
|
|
& & \multicolumn{2}{c}{Generated decay:} \\
|
| 410 |
ymaravin |
1.13 |
& & \multicolumn{2}{c}{$\Z \to \mu\mu $} \\
|
| 411 |
|
|
Selection channel & & $\W \to e\nu$ & $\W \to \mu\nu$
|
| 412 |
|
|
\\
|
| 413 |
vuko |
1.7 |
\hline \hline
|
| 414 |
|
|
\multicolumn{4}{c}{all} \\ \hline
|
| 415 |
ymaravin |
1.13 |
$2\mu1e$ & all & 1895 events & 2 events \\
|
| 416 |
|
|
$2\mu1e$ & matched \Z & 100\% & 100\%\\
|
| 417 |
|
|
$2\mu1e$ & matched \W & 99$\pm$1\% & 0\\
|
| 418 |
|
|
$2\mu1e$ & matched \WZ & 99$\pm$1\% & 0\\
|
| 419 |
|
|
\hline \hline
|
| 420 |
|
|
|
| 421 |
|
|
\multicolumn{4}{c}{exactly 1 \W lepton candidate} \\ \hline
|
| 422 |
|
|
$2\mu1e$ & all & 1847 events & 0 events \\
|
| 423 |
|
|
$2\mu1e$ & matched \Z & 100\% & 0\\
|
| 424 |
|
|
$2\mu1e$ & matched \W & 99$\pm$1\% & 0\\
|
| 425 |
|
|
$2\mu1e$ & matched \WZ & 99$\pm$1\% & 0\\
|
| 426 |
|
|
\hline \hline
|
| 427 |
|
|
|
| 428 |
|
|
\multicolumn{4}{c}{more than 1 \W lepton candidate} \\ \hline
|
| 429 |
|
|
$2\mu1e$ & all & 48 events & 2 events \\
|
| 430 |
|
|
$2\mu1e$ & matched \Z & 100\% & 100\%\\
|
| 431 |
|
|
$2\mu1e$ & matched \W & 94$\pm$3.5\%& 0\\
|
| 432 |
|
|
$2\mu1e$ & matched \WZ & 94$\pm$3.5\% & 0\\
|
| 433 |
vuko |
1.7 |
\hline \hline
|
| 434 |
ymaravin |
1.13 |
|
| 435 |
vuko |
1.7 |
\multicolumn{4}{c}{all} \\ \hline
|
| 436 |
ymaravin |
1.13 |
$3\mu$ & all & 0 events & 2251 events \\
|
| 437 |
|
|
$3\mu$ & matched \Z & 0 & 94$\pm$1\%\\
|
| 438 |
|
|
$3\mu$ & matched \W & 0 & 93$\pm$1\%\\
|
| 439 |
|
|
$3\mu$ & matched \WZ & 0 & 93$\pm$1\%\\
|
| 440 |
|
|
\hline \hline
|
| 441 |
|
|
|
| 442 |
|
|
\multicolumn{4}{c}{exactly 1 \W lepton candidate} \\ \hline
|
| 443 |
|
|
$3\mu$ & all & 0 events & 2207 events \\
|
| 444 |
|
|
$3\mu$ & matched \Z & 0 & 94$\pm$1\%\\
|
| 445 |
|
|
$3\mu$ & matched \W & 0 & 93$\pm$1\%\\
|
| 446 |
|
|
$3\mu$ & matched \WZ & 0 & 93$\pm$1\%\\
|
| 447 |
|
|
\hline \hline
|
| 448 |
|
|
|
| 449 |
|
|
\multicolumn{4}{c}{more than 1 \W lepton candidate} \\ \hline
|
| 450 |
|
|
$3\mu$ & all & 0 events & 44 events \\
|
| 451 |
|
|
$3\mu$ & matched \Z & 0 & 91$\pm$4\%\\
|
| 452 |
|
|
$3\mu$ & matched \W & 0 & 91$\pm$4\%\\
|
| 453 |
|
|
$3\mu$ & matched \WZ & 0 & 91$\pm$4\%\\ \hline \hline
|
| 454 |
vuko |
1.7 |
\end{tabular}
|
| 455 |
|
|
\end{center}
|
| 456 |
|
|
\caption{Fractions of MC \WZ events with correctly matched leptons
|
| 457 |
|
|
to true decay product of \W and \Z decays for final states
|
| 458 |
|
|
with generated $\Z\to \mu\mu$ decays}
|
| 459 |
|
|
\label{tab:wz-matcheffi-Zmumu}
|
| 460 |
|
|
\end{table}
|
| 461 |
|
|
|
| 462 |
vuko |
1.11 |
|
| 463 |
|
|
%\subsection{Signal extraction}
|
| 464 |
|
|
%\input D0Matrix
|
| 465 |
|
|
\input zjetbackground
|
| 466 |
|
|
|
| 467 |
|
|
|
| 468 |
vuko |
1.16 |
\subsection{Complementary studies: can we use the neutrino?}
|
| 469 |
|
|
|
| 470 |
|
|
In $\WZ \to \ell^{\pm}\nu \ellell (\ell=e,\mu)$ events, the neutrino
|
| 471 |
|
|
coming from the \W-boson decay leaves the detector with a significant
|
| 472 |
|
|
amount of energy, which should reflect in a large transverse missing
|
| 473 |
|
|
energy measurement. On the other side, no large MET is expected for
|
| 474 |
|
|
the most important background categories, especially \Zjets,
|
| 475 |
|
|
\Zbbbar, \ZZ and \Zgamma. This expectation is confirmed, as can be
|
| 476 |
|
|
seen in Figure~\ref{fig:met}.
|
| 477 |
|
|
|
| 478 |
|
|
Another variable sensitive to the presence of the neutrino
|
| 479 |
|
|
is the W transverse mass $m_T^W$, obtained by combining the missing
|
| 480 |
|
|
energy vector and the lepton associated to the \W-boson decay.
|
| 481 |
|
|
The distribution of $m_T^W$ is shown in Figure~\ref{fig:mtw}.
|
| 482 |
|
|
The signal yield could be extracted from that distribution.
|
| 483 |
|
|
This requires however additional studies and it has not been
|
| 484 |
|
|
done at this stage.
|
| 485 |
|
|
|
| 486 |
|
|
|
| 487 |
vuko |
1.11 |
\section{Systematic uncertainties}
|
| 488 |
|
|
\input Sys
|
| 489 |
|
|
|
| 490 |
|
|
|
| 491 |
|
|
\begin{figure}[bt]
|
| 492 |
|
|
\begin{center}
|
| 493 |
|
|
\scalebox{0.8}{\includegraphics{figs/met_by_channel.eps}}
|
| 494 |
|
|
\caption{Missing transverse mass for the four signal categories.
|
| 495 |
|
|
The distributions show the number of expected events
|
| 496 |
vuko |
1.15 |
for $1 fb^{-1}$. Only events with 81 GeV $< M_Z < $ 101 \gev
|
| 497 |
vuko |
1.11 |
are shown. All selection cuts are applied.}
|
| 498 |
|
|
\label{fig:met}
|
| 499 |
|
|
\end{center}
|
| 500 |
|
|
\end{figure}
|
| 501 |
|
|
|
| 502 |
|
|
\begin{figure}[bt]
|
| 503 |
|
|
\begin{center}
|
| 504 |
|
|
\scalebox{0.8}{\includegraphics{figs/mtw_by_channel.eps}}
|
| 505 |
ymaravin |
1.14 |
\caption{\W transverse mass for the four signal categories.
|
| 506 |
vuko |
1.11 |
The distributions show the number of expected events
|
| 507 |
vuko |
1.15 |
for $1 fb^{-1}$. Only events with 81 GeV $< M_Z < $ 101 GeV are shown.
|
| 508 |
vuko |
1.11 |
All selection cuts are applied.}
|
| 509 |
|
|
\label{fig:mtw}
|
| 510 |
|
|
\end{center}
|
| 511 |
|
|
\end{figure}
|
| 512 |
|
|
|
| 513 |
|
|
|
| 514 |
|
|
|
| 515 |
|
|
|
| 516 |
|
|
|
