| 36 |
|
\end{tabular} |
| 37 |
|
|
| 38 |
|
\end{center} |
| 39 |
< |
\caption{HLT Efficiencies, in percent, for all |
| 40 |
< |
the events in the generated phase space that have been retained by |
| 41 |
< |
the complete event selection.} |
| 39 |
> |
\caption{HLT Efficiencies for all the events in the generated phase space that |
| 40 |
> |
have been retained by the complete event selection.} |
| 41 |
|
\label{tab:hlteff} |
| 42 |
|
\end{table} |
| 43 |
|
|
| 85 |
|
These cuts reduce the background from muons originated in |
| 86 |
|
\b-quark decays of the $\Zbbbar$ background, which are close to tracks |
| 87 |
|
and clusters from the other \b-quark decay products. |
| 88 |
+ |
The signal and background distributions of these isolation variables |
| 89 |
+ |
are shown in Figure~\ref{fig:mu_isol} for the muon in $2e1\mu$ candidate |
| 90 |
+ |
events. |
| 91 |
|
|
| 92 |
|
%Figures~\ref{fig:muonisol} and ~\ref{fig:muonisoleffi} show the |
| 93 |
|
%performance of the isolation cut. The distribution of the isolation |
| 104 |
|
background comes from misidentified light quark jets. Thus, |
| 105 |
|
the requirement on the impact parameter significance does not |
| 106 |
|
increase the significance of the $\W\to e$ channels, as can be seen in |
| 107 |
< |
Fig.~\ref{fig:wl_IP_SvsCut}. |
| 107 |
> |
Fig.~\ref{fig:wl_IP_SvsCut}. The distribution of $S_{IP}$ for the muon |
| 108 |
> |
in $2e1\mu$ candidate events is shown in Figure~\ref{fig:mu_SIP}. |
| 109 |
|
|
| 110 |
|
\begin{figure}[p] |
| 111 |
|
\begin{center} |
| 114 |
|
of the requirement on the \W-boson lepton impact parameter |
| 115 |
|
significance. All other criteria but the one on impact parameter |
| 116 |
|
significance are applied. |
| 117 |
< |
% Only events with 81.1 GeV $< M_Z < $ 101.1 \gev |
| 117 |
> |
% Only events with 81 GeV $< M_Z < $ 101 \gev |
| 118 |
|
% are considered. |
| 119 |
|
} |
| 120 |
|
\label{fig:wl_IP_eff} |
| 127 |
|
\caption{Signal significance as a function of requirement on |
| 128 |
|
the \W-boson lepton impact parameter significance. All other criteria but |
| 129 |
|
the requirement on the impact parameter significance are applied. |
| 130 |
< |
% Only events with 81.1 GeV $< M_Z < $ 101.1 \gev are considered. |
| 130 |
> |
% Only events with 81 GeV $< M_Z < $ 101 \gev are considered. |
| 131 |
|
} |
| 132 |
|
\label{fig:wl_IP_SvsCut} |
| 133 |
|
\end{center} |
| 166 |
|
\caption{Efficiency for signal and background as a function |
| 167 |
|
of the cut value on the \W-boson lepton transverse momentum. |
| 168 |
|
All other cuts but the cut on this variable are applied. |
| 169 |
< |
Only events with 81.1 GeV $< M_Z < $ 101.1 \gev |
| 169 |
> |
Only events with 81 GeV $< M_Z < $ 101 \gev |
| 170 |
|
are considered.} |
| 171 |
|
\label{fig:wlpt_cuteff} |
| 172 |
|
\end{center} |
| 178 |
|
\caption{Signal significance as a function of the cut value on |
| 179 |
|
the \W-boson lepton transverse momentum. All other cuts but |
| 180 |
|
the cut on this variable are applied. Only events with |
| 181 |
< |
81.1 GeV $< M_Z < $ 101.1 \gev are considered.} |
| 181 |
> |
81 GeV $< M_Z < $ 101 \gev are considered.} |
| 182 |
|
\label{fig:wlpt_cutS} |
| 183 |
|
\end{center} |
| 184 |
|
\end{figure} |
| 209 |
|
%Figure~\ref{fig:dzmass}. |
| 210 |
|
|
| 211 |
|
After the \Z boson candidate is identified, the remaining leptons in the event |
| 212 |
< |
are required to pass the tight criteria described in~\cite{noteElectronID}. |
| 212 |
> |
are required, for electrons, to pass the tight criteria described in~\cite{noteElectronID} |
| 213 |
> |
or, for muons, all criteria described in section~\ref{sec:leptonId}. |
| 214 |
|
If more than one lepton candidate satisfies the tight requirements, the one with the |
| 215 |
|
highest $p_T$ is associated with \W boson decay. This lepton's $p_T$ is effective |
| 216 |
|
discriminant against \Zbbbar and \Zjets production (see Fig.~\ref{fig:wlpt_cuteff}). |
| 217 |
|
We require the transverse momentum to exceed 20 GeV, as it maximizes |
| 218 |
|
the significance of the \WZ\ signal with respect to background as shown in |
| 219 |
< |
Fig.~\ref{wlpt_cuteff}. |
| 219 |
> |
Fig.~\ref{fig:wlpt_cutS}. |
| 220 |
|
|
| 221 |
|
An additional requirement on the isolation between electron and muon candidates is applied |
| 222 |
|
for the $2\mu 1e$ channel, by demanding the value of $\Delta R$ between the electron |
| 240 |
|
on the third lepton, as leptons from $\tau$ decays are not as energetic as those from |
| 241 |
|
$\W \to \ell \nu$ processes. |
| 242 |
|
|
| 243 |
< |
In Tables~ref\label{tab:wz-matcheffi-Zee} and \label{tab:wz-matcheffi-Zmumu} we |
| 243 |
> |
In Tables~\ref{tab:wz-matcheffi-Zee} and \ref{tab:wz-matcheffi-Zmumu} we |
| 244 |
|
display the fraction of reconstructed \WZ events with correctly-matched leptons. |
| 245 |
|
It can be seen that the lepton associated with the \W boson decay is correctly matched |
| 246 |
|
to the true Monte Carlo lepton from the \W boson decay in more than 90\% of |
| 465 |
|
\input zjetbackground |
| 466 |
|
|
| 467 |
|
|
| 468 |
+ |
\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 |
|
\section{Systematic uncertainties} |
| 488 |
|
\input Sys |
| 489 |
|
|
| 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 |
< |
for $1 fb^{-1}$. Only events with 81.1 GeV $< M_Z < $ 101.1 \gev |
| 496 |
> |
for $1 fb^{-1}$. Only events with 81 GeV $< M_Z < $ 101 \gev |
| 497 |
|
are shown. All selection cuts are applied.} |
| 498 |
|
\label{fig:met} |
| 499 |
|
\end{center} |
| 502 |
|
\begin{figure}[bt] |
| 503 |
|
\begin{center} |
| 504 |
|
\scalebox{0.8}{\includegraphics{figs/mtw_by_channel.eps}} |
| 505 |
< |
\caption{W transverse mass for the four signal categories. |
| 505 |
> |
\caption{\W transverse mass for the four signal categories. |
| 506 |
|
The distributions show the number of expected events |
| 507 |
< |
for $1 fb^{-1}$. Only events with 81.1 GeV $< M_Z < $ 101.1 GeV are shown. |
| 507 |
> |
for $1 fb^{-1}$. Only events with 81 GeV $< M_Z < $ 101 GeV are shown. |
| 508 |
|
All selection cuts are applied.} |
| 509 |
|
\label{fig:mtw} |
| 510 |
|
\end{center} |
