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\section{Acceptance and efficiency systematics} |
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\label{sec:systematics} |
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{\bf \color{red} MANY OF THESE STUDIES NEED TO BE UPDATED WITH 38X MC} |
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This is a search for new physics contributions to |
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events with high \met and lots of jet activity. |
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As seen in Section~\ref{sec:results}, there is no |
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Nevertheless, we can make general statements about the |
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systematic uncertainties, including quantitative |
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estimates of the systematic uncertainties associated with |
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a few specific processes. |
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a few specific processes. Note that we have used Spring10 |
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MC for the studies of systematic uncertainties described in this section, |
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and we are currently checking if any of the reported values |
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change after switching to Fall10 MC. |
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The systematic uncertainty on the lepton acceptance consists |
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of two parts: the trigger efficiency uncertainty and the |
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$P_T>20$ GeV is very high, except in some corners |
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of phase space, see Section~\ref{sec:trgeffsum}. |
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We estimate the efficiency uncertainty to be a few percent, |
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mostly in the low $P_T$ region. |
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mostly in the low $P_T$ region. For $t\bar{t}$, LM0 and LM1 |
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we find trigger efficiency uncertainties of less than 1\%, evaluated |
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by taking the difference in yields in the signal region between |
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assuming 100\% trigger efficiency and using the trigger efficiency model. |
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% trigger efficiency uncertainties: ttbar 0.3%, LM0 0.6%, LM1 0.6% |
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\begin{figure}[tbh] |
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\begin{center} |
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\includegraphics[width=1.0\linewidth]{eff_35.png} |
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\includegraphics[width=1.0\linewidth]{isoEff.png} |
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\includegraphics[width=1.0\linewidth]{ttdilD6T_eff_Dec02_38X.png} |
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\includegraphics[width=1.0\linewidth]{lm_eff_Dec02_38X.png} |
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\caption{\label{fig:effttbar}\protect |
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Identification and isolation efficiencies for |
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leptons from $t \to W \to \ell$ and |
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\begin{center} |
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\caption{\label{tab:tagandprobe} Tag and probe results on $Z \to \ell \ell$ |
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on data and MC. We quote ID efficiency given isolation and |
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the isolation efficiency given ID.} |
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the isolation efficiency given ID. } |
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\begin{tabular}{|l||c|c|} |
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\hline |
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& Data T\&P & MC T\&P \\ \hline |
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$\epsilon(id|iso)$ electrons & $0.909\pm0.006$ & 0.926 \\ |
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$\epsilon(iso|id)$ electrons & $0.987\pm0.003$ & 0.985 \\ |
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$\epsilon(id|iso)$ muons & $0.955\pm0.003$ & 0.953 \\ |
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$\epsilon(iso|id)$ muons & $0.984\pm0.003$ & 0.981 \\ |
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& Data T\&P & MC T\&P \\ |
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\hline |
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$\epsilon(id|iso)$ electrons & $0.925 \pm 0.007$ & $0.934 \pm 0.004$ \\ |
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$\epsilon(iso|id)$ electrons & $0.991 \pm 0.002$ & $0.987 \pm 0.002$ \\ |
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$\epsilon(id|iso)$ muons & $0.962 \pm 0.005$ & $0.984 \pm 0.002$ \\ |
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$\epsilon(iso|id)$ muons & $0.987 \pm 0.003$ & $0.982 \pm 0.002$ \\ |
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\hline |
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\end{tabular} |
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\end{center} |
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the final state. For example, in MC we find that the |
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lepton isolation efficiency differs by $\approx 4\%$ |
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{\bf per lepton} between $Z$ events and $t\bar{t}$ events\cite{ref:top}. |
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{\bf \color{red} This difference has been evaluated with Spring10 MC, currently checking with Fall10 MC. } |
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%\noindent {\bf This figure should be cut off at 100 GeV, and |
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%the y-axis should be zero-suppressed} |
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assuming a 5\% uncertainty to the hadronic energy scale in CMS. |
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For $t\bar{t}$ we find uncertainties of 8\% (baseline |
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selection) and 30\% (signal region D); for LM0 and LM1 we find |
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14\% and 6\% respectively for signal region D. |
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selection) and 27\% (signal region D) ({\bf \color{red} This number |
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needs to be double-checked, Derek finds 33\%.}); for LM0 and LM1 we find |
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14\% and 6\% respectively for signal region D. |
