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root/cvsroot/UserCode/benhoob/cmsnotes/OSPAS2011/limit.tex
Revision: 1.7
Committed: Wed Jun 15 09:14:50 2011 UTC (13 years, 11 months ago) by nmohr
Content type: application/x-tex
Branch: MAIN
Changes since 1.6: +5 -4 lines
Log Message:
New combined limit

File Contents

# Content
1 \section{Limits on New Physics}
2 \label{sec:limit}
3
4 We set an upper limit on the signal yield extracted by the fit to the dilepton mass
5 distribution, assuming the LM1 shape. The 95\% confidence level (CL) upper limit (UL)
6 is extracted using a profile likelihood technique, giving an UL of 14.3 events, including
7 uncertainties in the background yield and shape, resolution model and $Z$ yield.
8 In the limit setting we also include the uncertainties from trigger efficiency,
9 lepton selection efficiency, hadronic energy scale and integrated luminosity on the signal efficiency.
10 The expected LM1 yield is 23 $\pm$ 3 events.
11
12 We set upper limits on the non-SM contributions to the high \MET\ and high \Ht\ signal regions.
13 For both regions, we find reasonable agreement between the observed yields and the predictions from MC and from the 2
14 data-driven methods. We choose here to extract the upper limits using the MC prediction for the
15 background estimate. The 95\% CL upper limit is extracted using a Bayesian technique~\cite{ref:cl95cms},
16 with a log-normal model of nuissance parameter integration assuming 0 signal . The results are summarized in
17 Table~\ref{tab:results}. Based on these results, we exclude LM1 and LM3.
18
19 \begin{table}[hbt]
20 \begin{center}
21 \caption{\label{tab:results}
22 Summary of the observed and predicted yields in the 2 signal regions. The error in the MC prediction is statistical only.
23 The systematic uncertainties on the ABCD', \ptll, and OF subtraction predictions are discussed in the text. The non-SM yield UL is a
24 Bayesian 95\% confidence level upper limit. The LM1 and LM3 yields include uncertainties from trigger efficiency,
25 lepton selection efficiency, hadronic energy scale and integrated luminosity.
26 }
27 \begin{tabular}{|l|c|c|c}
28 \hline
29 & high \met\ signal region & high \Ht\ signal region \\
30 \hline
31 Observed yield & 4 & 3 \\
32 \hline
33 MC prediction & 2.6 $\pm$ 0.8 & 2.5 $\pm$ 0.8 \\
34 ABCD' prediction & 1.2 $\pm$ 0.4 (stat) $\pm$ 0.5 (syst) & 0.0 $\pm$ 0.6 (stat) $\pm$ 0.3 (syst) \\
35 \ptll\ prediction & 5.4 $\pm$ 3.8 (stat) $\pm$ 2.2 (syst) & 1.7 $\pm$ 1.7 (stat) $\pm$ 0.6 (syst) \\
36 non-SM yield UL & 5.2 & 4.1 \\
37 LM1 yield & 17 $\pm$ 3.1 & 14 $\pm$ 3.1 \\
38 LM3 yield & 6.4 $\pm$ 1.3 & 6.7 $\pm$ 1.6 \\
39 \hline
40 OF subtraction ($\Delta$) & 1.3 $\pm$ 1.9 (stat) $\pm$ 0.1 (syst) & 0.1 $\pm$ 1.5 (stat) $\pm$ 0.0 (syst) \\
41 \hline
42 \end{tabular}
43 \end{center}
44 \end{table}