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Revision: 1.12
Committed: Thu Nov 11 15:43:50 2010 UTC (14 years, 5 months ago) by benhoob
Content type: application/x-tex
Branch: MAIN
Changes since 1.11: +12 -10 lines
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# User Rev Content
1 benhoob 1.7 \clearpage
2    
3 claudioc 1.1 \section{Results}
4     \label{sec:results}
5    
6     \begin{figure}[tbh]
7     \begin{center}
8 benhoob 1.7 \includegraphics[width=0.75\linewidth]{abcd_35pb.png}
9 claudioc 1.1 \caption{\label{fig:abcdData}\protect Distributions of SumJetPt
10     vs. MET$/\sqrt{\rm SumJetPt}$ for SM Monte Carlo and data. Here we also
11     show our choice of ABCD regions.}
12     \end{center}
13     \end{figure}
14    
15 claudioc 1.2 The data, together with SM expectations is presented
16 benhoob 1.7 in Figure~\ref{fig:abcdData}. We see 1 event in the
17     signal region (region $D$). The Standard Model MC
18     expectation is 1.4 events.
19 claudioc 1.2
20     \subsection{Background estimate from the ABCD method}
21     \label{sec:abcdres}
22    
23     The data yields in the
24     four regions are summarized in Table~\ref{tab:datayield}.
25 benhoob 1.7 The prediction of the ABCD method is is given by $A\times C/B$ and
26 benhoob 1.10 is 1.5 $\pm$ 0.9 events (statistical uncertainty only, assuming
27     Gaussian errors). (see Table~\ref{tab:datayield}).
28 claudioc 1.2
29 claudioc 1.1 \begin{table}[hbt]
30     \begin{center}
31     \caption{\label{tab:datayield} Data yields in the four
32 benhoob 1.7 regions of Figure~\ref{fig:abcdData}, as well as the predicted yield in region D given
33     by A$\times$C / B. The quoted uncertainty
34 benhoob 1.4 on the prediction in data is statistical only, assuming Gaussian errors.
35 benhoob 1.7 We also show the SM Monte Carlo expectations, scaled to 34.85~pb$^{-1}$.}
36     \begin{tabular}{l||c|c|c|c||c}
37     \hline
38     sample & A & B & C & D & A$\times$C / B \\
39     \hline
40     $t\bar{t}\rightarrow \ell^{+}\ell^{-}$ & 7.96 & 33.07 & 4.81 & 1.20 & 1.16 \\
41     $t\bar{t}\rightarrow \mathrm{other}$ & 0.15 & 0.85 & 0.09 & 0.04 & 0.02 \\
42     $Z^0$ + jets & 0.00 & 1.16 & 0.08 & 0.08 & 0.00 \\
43     $W^{\pm}$ + jets & 0.00 & 0.10 & 0.00 & 0.00 & 0.00 \\
44     $W^+W^-$ & 0.19 & 0.29 & 0.02 & 0.07 & 0.02 \\
45     $W^{\pm}Z^0$ & 0.03 & 0.04 & 0.01 & 0.01 & 0.00 \\
46     $Z^0Z^0$ & 0.00 & 0.03 & 0.00 & 0.00 & 0.00 \\
47     single top & 0.28 & 1.00 & 0.04 & 0.01 & 0.01 \\
48     \hline
49     total SM MC & 8.61 & 36.54 & 5.05 & 1.41 & 1.19 \\
50 claudioc 1.1 \hline
51 benhoob 1.7 data & 11 & 36 & 5 & 1 &1.53 $\pm$ 0.86 \\
52 claudioc 1.1 \hline
53     \end{tabular}
54     \end{center}
55     \end{table}
56    
57 claudioc 1.3 %As a cross-check, we can subtract from the yields in
58     %Table~\ref{tab:datayield} the expected DY contributions
59     %from Table~\ref{tab:ABCD-DY} in order to get a ``purer''
60     %estimate of the $t\bar{t}$ contribution. The result
61     %of this exercise is {\color{red} xx} events.
62 claudioc 1.2
63 benhoob 1.10 \clearpage
64    
65 claudioc 1.2 \subsection{Background estimate from the $P_T(\ell\ell)$ method}
66     \label{sec:victoryres}
67    
68 benhoob 1.11 We first use the $P_T(\ell \ell)$ method to predict the number of events
69 benhoob 1.12 in control region A, defined in Sec.~\ref{sec:abcd} as
70     $125<{\rm SumJetPt}>300$~GeV and $\met/\sqrt{\rm SumJetPt}>$8.5.
71     We count the number of events in region
72     $A'$, defined in Sec.~\ref{sec:othBG} by replacing the above $\met/\sqrt{\rm SumJetPt}$
73     cut with the same cut on the quantity $P_T(\ell\ell)/\sqrt{\rm SumJetPt}$,
74     and find $N_{A'}=6$. To predict the yield in region A we take
75     $N_A = K \cdot K_C \cdot N_{A'} = 10.4 \pm 4.2$
76 benhoob 1.11 (statistical uncertainty only, assuming Gaussian errors),
77     where we have taken $K = 1.73$ and $K_C = 1$. This yield is in good
78     agreement with the observed yield of 11 events, as shown in
79     Table~\ref{tab:victory_control} and displayed in Fig.~\ref{fig:victory} (left).
80 benhoob 1.12 {\color{red} \bf Perform DY estimate for this control region}.
81 benhoob 1.11
82     Encouraged by the good agreement between predicted and observed yields
83     in the control region, we proceed to perform the $P_T(\ell \ell)$ method
84     in the signal region ${\rm SumJetPt}>300$~GeV.
85 claudioc 1.2 The number of data events in region $D'$, which is defined in
86     Section~\ref{sec:othBG} to be the same as region $D$ but with the
87     $\met/\sqrt{\rm SumJetPt}$ requirement
88 benhoob 1.11 replaced by a $P_T(\ell\ell)/\sqrt{\rm SumJetPt}$ requirement,
89 benhoob 1.8 is $N_{D'}=2$. Thus the BG prediction is
90 benhoob 1.11 $N_D = K \cdot K_C \cdot N_{D'} = 3.07 \pm 2.17$ where $K=1.54 \pm xx$
91     as derived in Sec.~\ref{sec:victory} and $K_C = 1$.
92     We next subtract off the expected DY contribution of
93     {\color{red} \bf 0.8 $\pm$ 0.8 (update DY estimate)} events, as calculated
94     in Sec.~\ref{sec:othBG}. This gives a predicted yield of
95     $N_D=1.8^{+2.5}_{-1.8}$ events, which is consistent with the observed yield of
96 benhoob 1.12 1 event, as summarized in Table~\ref{tab:victory_signal} and Fig.~\ref{fig:victory}
97     (right).
98 benhoob 1.11
99 claudioc 1.1
100 claudioc 1.3 \begin{figure}[hbt]
101     \begin{center}
102 benhoob 1.8 \includegraphics[width=0.48\linewidth]{victory_control_35pb.png}
103     \includegraphics[width=0.48\linewidth]{victory_signal_35pb.png}
104 claudioc 1.3 \caption{\label{fig:victory}\protect Distributions of
105     tcMet/$\sqrt{\rm SumJetPt}$ for the control and signal region.
106     We show the oberved distributions in both Monte Carlo and data.
107     We also show the distributions predicted from
108 benhoob 1.4 ${P_T(\ell\ell)}/\sqrt{\rm SumJetPt}$ in both MC and data.}
109 claudioc 1.3 \end{center}
110     \end{figure}
111    
112    
113 benhoob 1.9 \begin{table}[hbt]
114     \begin{center}
115     \label{tab:victory_control}
116     \caption{Results of the dilepton $p_{T}$ template method in the control region
117     $125 < \mathrm{sumJetPt} < 300$~GeV. The predicted and observed yields for
118     the region $\mathrm{tcmet}/\sqrt{\mathrm{sumJetPt}}>$~8.5 are shown for data
119     and MC. The error on the prediction for data is statistical only, assuming
120     Gaussian errors.}
121     \begin{tabular}{l|c|c|c}
122     \hline
123     & Predicted & Observed & Obs/Pred \\
124     \hline
125     total SM MC & 7.10 & 8.61 & 1.21 \\
126     data & 10.38 $\pm$ 4.24 & 11 & 1.06 \\
127     \hline
128     \end{tabular}
129     \end{center}
130     \end{table}
131    
132     \begin{table}[hbt]
133     \begin{center}
134 benhoob 1.12 \label{tab:victory_signal}
135 benhoob 1.9 \caption{Results of the dilepton $p_{T}$ template method in the signal region
136     $125 < \mathrm{sumJetPt} < 300$~GeV. The predicted and observed yields for
137     the region $\mathrm{tcmet}/\sqrt{\mathrm{sumJetPt}}>$~8.5 are shown for data
138     and MC. The error on the prediction for data is statistical only, assuming
139     Gaussian errors.}
140     \begin{tabular}{l|c|c|c}
141     \hline
142 benhoob 1.11 & Predicted & Observed & Obs/Pred \\
143 benhoob 1.9 \hline
144 benhoob 1.11 total SM MC & 0.96 & 1.41 & 1.46 \\
145 benhoob 1.12 data & $1.8^{+2.5}_{-1.8}$ & 1 & 0.56 \\
146 benhoob 1.9 \hline
147     \end{tabular}
148     \end{center}
149     \end{table}
150    
151    
152 claudioc 1.3 \subsection{Summary of results}
153 claudioc 1.1 To summarize: we see no evidence for an anomalous
154     rate of opposite sign isolated dilepton events
155     at high \met and high SumJetPt. The extraction of
156     quantitative limits on new physics models is discussed
157 benhoob 1.5 in Section~\ref{sec:limit}.