| 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 |
| 251 |
|
\begin{table}[p] |
| 252 |
|
\begin{center} |
| 253 |
|
|
| 254 |
< |
|
| 251 |
< |
|
| 252 |
< |
|
| 253 |
< |
\begin{tabular}{lcc|cc|cc|cc|c} \hline \hline |
| 254 |
> |
\begin{tabular}{lcc|cc|cc|cc|} \hline |
| 255 |
|
\multicolumn{9}{c}{ {\bf $3e$ Channel}} \\ \hline \hline |
| 256 |
< |
Step & \WZ & $\epsilon$ & $b\bar{b}\ell\ell$ & $\epsilon$ & $\Z+jets$ & $\epsilon$ & $t\bar{t}+jets$ & $\epsilon$ \\ \hline |
| 257 |
< |
All events & 546 & & 72,700 & & 1,268,000 & & 17,600 & \\ |
| 258 |
< |
Found $\Z \to ee$ & 205 & 38\% & 27,800 & 38\% & 502,300 & 40\% & 2,920 & 17\% \\ |
| 259 |
< |
Found $\W \to e\nu$ & 42.0 & 21\% & 171 & 0.6\% & 309.6 & 0.06\% & 13.8 & 0.5\% \\ |
| 260 |
< |
\W lepton $p_T$ cut & 34.9 & 83\% & 23.7 & 14\% & 86.8 & 28 \% & 8.3 & 60\% \\ |
| 261 |
< |
Passes HLT & 34.7 & 100\% & 23.6 & 99\% & 86.8 &100\% & 8.3 & 100\% \\ |
| 262 |
< |
\Z mass window & 31.6 & 91\% & 17.5 & 74\% & 51.9 &60\% & 3.3 & 39\% \\ \hline |
| 263 |
< |
Overall efficiency & & 5.8\% & & 0.024\% & & 0.0041\% & & 0.019\% \\ |
| 264 |
< |
\hline\hline |
| 265 |
< |
|
| 256 |
> |
Step & $\WZ \to 3e$ & $ \epsilon$ & Z+jets & $ \epsilon$ & TTbar+jets & $ \epsilon$ & bbll & $ \epsilon$\\ \hline |
| 257 |
> |
All events & 185 & & $5.82\cdot 10^6$ & & $8.27\cdot 10^5$ & & $1.44\cdot 10^5$ & \\ |
| 258 |
> |
Found $Z \to ee$ & 73.9 & 39.9 \% & $5.02\cdot 10^5$ & 8.63 \% & $2.92\cdot 10^3$ & 0.353 \% & $2.78\cdot 10^4$ & 19.4 \% \\ |
| 259 |
> |
Second Z veto & 73.9 & 100 \% & $5.02\cdot 10^5$ & 100 \% & $2.92\cdot 10^3$ & 99.9 \% & $2.78\cdot 10^4$ & 100 \% \\ |
| 260 |
> |
Found $W \to e$ & 37.4 & 50.6 \% & 310 & 0.0616 \% & 13.8 & 0.474 \% & 171 & 0.614 \% \\ |
| 261 |
> |
W Lepton Pt cut & 32.5 & 86.7 \% & 86.8 & 28 \% & 8.26 & 59.7 \% & 23.4 & 13.7 \% \\ |
| 262 |
> |
Passes HLT & 32.3 & 99.6 \% & 86.8 & 100 \% & 8.26 & 100 \% & 23.3 & 99.7 \% \\ |
| 263 |
> |
Z mass window & 29.5 & 91.2 \% & 51.9 & 59.8 \% & 3.26 & 39.5 \% & 17.3 & 74 \% \\ |
| 264 |
> |
\hline |
| 265 |
> |
Overall efficiency & & 15.9 \% & & 0.000892 \% & & 0.000394 \% & & 0.012 \% \\ |
| 266 |
> |
\hline |
| 267 |
> |
%\end{tabular} |
| 268 |
> |
%\begin{tabular}{lcc|cc|cc|cc|} \hline |
| 269 |
|
\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 |
< |
|
| 270 |
> |
Step & $\WZ \to 2e1\mu$ & $ \epsilon$ & Z+jets & $ \epsilon$ & TTbar+jets & $ \epsilon$ & bbll & $ \epsilon$\\ \hline |
| 271 |
> |
All events & 185 & & $5.82\cdot 10^6$ & & $8.27\cdot 10^5$ & & $1.44\cdot 10^5$ & \\ |
| 272 |
> |
Found $Z \to ee$ & 63.8 & 34.5 \% & $5.02\cdot 10^5$ & 8.63 \% & $2.92\cdot 10^3$ & 0.353 \% & $2.78\cdot 10^4$ & 19.4 \% \\ |
| 273 |
> |
Second Z veto & 63.7 & 99.9 \% & $5.02\cdot 10^5$ & 100 \% & $2.92\cdot 10^3$ & 99.9 \% & $2.78\cdot 10^4$ & 100 \% \\ |
| 274 |
> |
Found $W \to \mu$ & 42.6 & 66.8 \% & $2.19\cdot 10^3$ & 0.437 \% & 55.6 & 1.91 \% & 748 & 2.69 \% \\ |
| 275 |
> |
W Lepton Pt cut & 35.1 & 82.5 \% & 9.58 & 0.436 \% & 16.4 & 29.5 \% & 9.49 & 1.27 \% \\ |
| 276 |
> |
Passes HLT & 34.3 & 97.6 \% & 8.32 & 86.9 \% & 14.1 & 86 \% & 9.12 & 96.1 \% \\ |
| 277 |
> |
Z mass window & 30.8 & 89.8 \% & 7.31 & 87.9 \% & 3.76 & 26.7 \% & 8 & 87.8 \% \\ |
| 278 |
> |
\hline |
| 279 |
> |
Overall efficiency & & 16.7 \% & & 0.000126 \% & & 0.000454 \% & & 0.00557 \% \\ |
| 280 |
> |
\hline |
| 281 |
> |
%\end{tabular} |
| 282 |
> |
%\begin{tabular}{lcc|cc|cc|cc|} \hline |
| 283 |
|
\multicolumn{9}{c}{ {\bf $2\mu1e$ Channel}} \\ \hline \hline |
| 284 |
< |
Step & \WZ & $\epsilon$ & $b\bar{b}\ell\ell$ & $\epsilon$ & $\Z+jets$ & $\epsilon$ & $t\bar{t}+jets$ & $\epsilon$ \\ \hline |
| 285 |
< |
All events & 546 & & 72,770 & & 1,268,000 & & 17,600 & \\ |
| 286 |
< |
Found $\Z \to \mu\mu$ & 234 &43\%& 31,890 & 44\% & 577,200 & 46\% & 2779 & 16\% \\ |
| 287 |
< |
Found $\W \to e\nu$ & 48.8 &21\%& 214 & 0.67\% & 702 & 0.12\% & 15.1 & 0.54\% \\ |
| 288 |
< |
\W lepton $p_T$ cut & 40.7 &83\%& 50.6 & 24\% & 464.0 & 66\% & 10.3 & 68\% \\ |
| 289 |
< |
$\Delta R(e,\mu)$ cut & 40.6&100\%& 23.3 & 46\% & 93.0 & 20\% & 7.1 & 70\% \\ |
| 290 |
< |
Passes HLT & 39.4 &97\%& 23.2 & 99\% & 88.8 & 95\% & 6.6 & 93\% \\ |
| 291 |
< |
\Z mass window & 35.6 & 90\% & 18.9 & 81\% & 50.3 & 57\% & 2.8 &44\% \\ \hline |
| 292 |
< |
Overall efficiency & &6.5\% & & 0.026\% & & 0.0040\% & & 0.016\% \\ |
| 293 |
< |
\hline \hline |
| 294 |
< |
|
| 284 |
> |
Step & $\WZ \to 2\mu1e$ & $ \epsilon$ & Z+jets & $ \epsilon$ & TTbar+jets & $ \epsilon$ & bbll & $ \epsilon$\\ \hline |
| 285 |
> |
All events & 190 & & $5.82\cdot 10^6$ & & $8.27\cdot 10^5$ & & $1.44\cdot 10^5$ & \\ |
| 286 |
> |
Found $Z \to \mu\mu$ & 75.2 & 39.7 \% & $5.77\cdot 10^5$ & 9.92 \% & $2.78\cdot 10^3$ & 0.336 \% & $3.19\cdot 10^4$ & 22.2 \% \\ |
| 287 |
> |
Second Z veto & 75.2 & 100 \% & $5.77\cdot 10^5$ & 100 \% & $2.77\cdot 10^3$ & 99.9 \% & $3.19\cdot 10^4$ & 100 \% \\ |
| 288 |
> |
Found $W \to e$ & 44 & 58.5 \% & 702 & 0.122 \% & 15.1 & 0.544 \% & 213 & 0.669 \% \\ |
| 289 |
> |
W Lepton Pt cut & 38.4 & 87.2 \% & 464 & 66.2 \% & 10.3 & 68 \% & 50.5 & 23.7 \% \\ |
| 290 |
> |
$\Delta R(e,\mu)$ cut & 38.4 & 99.9 \% & 93 & 20 \% & 7.15 & 69.6 \% & 23.3 & 46 \% \\ |
| 291 |
> |
Passes HLT & 37.3 & 97.1 \% & 88.8 & 95.5 \% & 6.62 & 92.7 \% & 23.1 & 99.4 \% \\ |
| 292 |
> |
Z mass window & 33.6 & 90.1 \% & 50.3 & 56.6 \% & 2.84 & 42.9 \% & 18.8 & 81.4 \% \\ |
| 293 |
> |
\hline |
| 294 |
> |
Overall efficiency & & 17.7 \% & & 0.000864 \% & & 0.000344 \% & & 0.0131 \% \\ |
| 295 |
> |
\hline |
| 296 |
> |
%\end{tabular} |
| 297 |
> |
%\begin{tabular}{lcc|cc|cc|cc|} \hline |
| 298 |
|
\multicolumn{9}{c}{ {\bf $3\mu$ Channel}} \\ \hline \hline |
| 299 |
< |
Step & \WZ & $\epsilon$ & ${b\bar{b}\ell\ell}$ & $\epsilon$ & $\Z+jets$ & $\epsilon$ & ${t\bar{t}+jets}$ & $\epsilon$ \\ \hline |
| 300 |
< |
All events & 546 & & 72,770 & & 1,268,000 & & 17,600 & \\ |
| 301 |
< |
Found $Z \to \mu\mu$ & 234 & 43\% & 31,900 & 44\% & 577,000 & 45\% & 2779 & 16 \% \\ |
| 302 |
< |
Found $W \to \mu$ & 58 & 25 \% & 811 & 2.5\% & 2521 & 0.44\% & 35.3 & 1.23 \% \\ |
| 303 |
< |
W Lepton Pt cut & 44.2 & 77 \% & 8.9 & 1.1\% & 1.8 & 0.07\% & 1.7 & 4.8 \% \\ |
| 304 |
< |
Passes HLT & 44.0 & 99\% & 8.9 & 100\% & 1.8 & 100 \% & 1.7 & 100 \% \\ |
| 305 |
< |
Z mass window & 40.0 & 91 \%) & 7.8 & 88\% & 1.8 & 100 \% & 1.2 & 69\% \\ \hline |
| 306 |
< |
Overall efficiency & & 7.3 \% & & 0.011\% & & 0.00015\% & & 0.0065\% \\ |
| 299 |
> |
Step & $\WZ \to 3\mu$ & $ \epsilon$ & Z+jets & $ \epsilon$ & TTbar+jets & $ \epsilon$ & bbll & $ \epsilon$\\ \hline |
| 300 |
> |
All events & 189 & & $5.82\cdot 10^6$ & & $8.27\cdot 10^5$ & & $1.44\cdot 10^5$ & \\ |
| 301 |
> |
Found $Z \to \mu\mu$ & 83.8 & 44.3 \% & $5.77\cdot 10^5$ & 9.92 \% & $2.78\cdot 10^3$ & 0.336 \% & $3.19\cdot 10^4$ & 22.2 \% \\ |
| 302 |
> |
Second Z veto & 83.6 & 99.8 \% & $5.77\cdot 10^5$ & 100 \% & $2.77\cdot 10^3$ & 99.9 \% & $3.19\cdot 10^4$ & 100 \% \\ |
| 303 |
> |
Found $W \to \mu$ & 51.8 & 62 \% & $2.52\cdot 10^3$ & 0.437 \% & 34.8 & 1.25 \% & 810 & 2.54 \% \\ |
| 304 |
> |
W Lepton Pt cut & 42.5 & 81.9 \% & 1.84 & 0.073 \% & 1.16 & 3.33 \% & 8.89 & 1.1 \% \\ |
| 305 |
> |
Passes HLT & 42.2 & 99.4 \% & 1.84 & 100 \% & 1.16 & 100 \% & 8.89 & 100 \% \\ |
| 306 |
> |
Z mass window & 38.5 & 91.1 \% & 1.84 & 100 \% & 1.16 & 100 \% & 7.78 & 87.5 \% \\ |
| 307 |
> |
\hline |
| 308 |
> |
Overall efficiency & & 20.3 \% & & 3.17e-05 \% & & 0.00014 \% & & 0.00542 \% \\ |
| 309 |
|
\hline |
| 310 |
|
\end{tabular} |
| 311 |
|
|
| 300 |
– |
|
| 312 |
|
\caption{Expected number of signal and background events passing the different |
| 313 |
|
selections steps together with the efficiency of each requirement and total efficiency of |
| 314 |
|
selection criteria in the \WZ, \Zbbbar, \Zjets and \ttjets samples for an integrated luminosity |
| 472 |
|
\input zjetbackground |
| 473 |
|
|
| 474 |
|
|
| 475 |
+ |
\subsection{Complementary studies: can we use the neutrino?} |
| 476 |
+ |
|
| 477 |
+ |
In $\WZ \to \ell^{\pm}\nu \ellell (\ell=e,\mu)$ events, the neutrino |
| 478 |
+ |
coming from the \W-boson decay leaves the detector with a significant |
| 479 |
+ |
amount of energy, which should reflect in a large transverse missing |
| 480 |
+ |
energy measurement. On the other side, no large MET is expected for |
| 481 |
+ |
the most important background categories, especially \Zjets, |
| 482 |
+ |
\Zbbbar, \ZZ and \Zgamma. This expectation is confirmed, as can be |
| 483 |
+ |
seen in Figure~\ref{fig:met}. |
| 484 |
+ |
|
| 485 |
+ |
Another variable sensitive to the presence of the neutrino |
| 486 |
+ |
is the W transverse mass $m_T^W$, obtained by combining the missing |
| 487 |
+ |
energy vector and the lepton associated to the \W-boson decay. |
| 488 |
+ |
The distribution of $m_T^W$ is shown in Figure~\ref{fig:mtw}. |
| 489 |
+ |
The signal yield could be extracted from that distribution. |
| 490 |
+ |
This requires however additional studies and it has not been |
| 491 |
+ |
done at this stage. |
| 492 |
+ |
|
| 493 |
+ |
|
| 494 |
|
\section{Systematic uncertainties} |
| 495 |
|
\input Sys |
| 496 |
|
|
| 498 |
|
\begin{figure}[bt] |
| 499 |
|
\begin{center} |
| 500 |
|
\scalebox{0.8}{\includegraphics{figs/met_by_channel.eps}} |
| 501 |
< |
\caption{Missing transverse mass for the four signal categories. |
| 501 |
> |
\caption{Missing transverse energy for the four signal categories. |
| 502 |
|
The distributions show the number of expected events |
| 503 |
< |
for $1 fb^{-1}$. Only events with 81.1 GeV $< M_Z < $ 101.1 \gev |
| 503 |
> |
for $1 fb^{-1}$. Only events with 81 GeV $< M_Z < $ 101 \gev |
| 504 |
|
are shown. All selection cuts are applied.} |
| 505 |
|
\label{fig:met} |
| 506 |
|
\end{center} |
| 509 |
|
\begin{figure}[bt] |
| 510 |
|
\begin{center} |
| 511 |
|
\scalebox{0.8}{\includegraphics{figs/mtw_by_channel.eps}} |
| 512 |
< |
\caption{W transverse mass for the four signal categories. |
| 512 |
> |
\caption{\W transverse mass for the four signal categories. |
| 513 |
|
The distributions show the number of expected events |
| 514 |
< |
for $1 fb^{-1}$. Only events with 81.1 GeV $< M_Z < $ 101.1 GeV are shown. |
| 514 |
> |
for $1 fb^{-1}$. Only events with 81 GeV $< M_Z < $ 101 GeV are shown. |
| 515 |
|
All selection cuts are applied.} |
| 516 |
|
\label{fig:mtw} |
| 517 |
|
\end{center} |
