| 8 |
|
\met/$\sqrt{\rm SumJetPt}>8.5$ GeV$^{\frac{1}{2}}$. |
| 9 |
|
|
| 10 |
|
The background prediction from the SM Monte Carlo is |
| 11 |
< |
1.4 $\pm$ 0.5 events, where the uncertainty comes from |
| 12 |
< |
the jet energy scale (30\%, see Section~\ref{sec:systematics}), |
| 13 |
< |
the luminosity (10\%), and the lepton/trigger |
| 14 |
< |
efficiency (10\%)\footnote{Other uncertainties associated with |
| 15 |
< |
the modeling of $t\bar{t}$ in MadGraph have not been evaluated. |
| 16 |
< |
The uncertainty on $pp \to \sigma(t\bar{t})$ is also not included.}. |
| 11 |
> |
1.3 events. |
| 12 |
> |
%, where the uncertainty comes from |
| 13 |
> |
%the jet energy scale (30\%, see Section~\ref{sec:systematics}), |
| 14 |
> |
%the luminosity (10\%), and the lepton/trigger |
| 15 |
> |
%efficiency (10\%)\footnote{Other uncertainties associated with |
| 16 |
> |
%the modeling of $t\bar{t}$ in MadGraph have not been evaluated. |
| 17 |
> |
%The uncertainty on $pp \to \sigma(t\bar{t})$ is also not included.}. |
| 18 |
|
The data driven background predictions from the ABCD method |
| 19 |
< |
and the $P_T(\ell\ell)$ method are 1.5 $\pm$ 0.9 and |
| 20 |
< |
$2.5 \pm 2.2$ events, respectively. |
| 19 |
> |
and the $P_T(\ell\ell)$ method are $1.5 \pm 0.9({\rm stat}) \pm 0.3({\rm syst})$ |
| 20 |
> |
and $4.3 \pm 3.0({\rm stat}) \pm 1.2({\rm syst})$, respectively. |
| 21 |
|
|
| 22 |
|
These three predictions are in good agreement with each other |
| 23 |
|
and with the observation of one event in the signal region. |
| 24 |
|
We calculate a Bayesian 95\% CL upper limit\cite{ref:bayes.f} |
| 25 |
|
on the number of non SM events in the signal region to be 4.1. |
| 26 |
< |
This was calculated using a background prediction of $N_{BG}=1.4 \pm 1.1$ |
| 26 |
> |
We have also calculated this limit using a profile likelihood method |
| 27 |
> |
as implemented in the cl95cms software, and we also find 4.1. |
| 28 |
> |
These limits were calculated using a background prediction of $N_{BG}=1.7 \pm 1.1$ |
| 29 |
|
events. The upper limit is not very sensitive to the choice of |
| 30 |
|
$N_{BG}$ and its uncertainty. |
| 31 |
|
|
| 32 |
|
To get a feeling for the sensitivity of this search to some |
| 33 |
|
popular SUSY models, we remind the reader of the number of expected |
| 34 |
< |
LM0 and LM1 events from Table~\ref{tab:sigcont}: $6.5 \pm 1.3$ |
| 35 |
< |
events and $2.6 \pm 0.4$ respectively, where the uncertainties |
| 34 |
> |
LM0 and LM1 events from Table~\ref{tab:sigcont}: $6.3 \pm 1.3$ |
| 35 |
> |
events and $2.6 \pm 0.4$ |
| 36 |
> |
respectively, where the uncertainties |
| 37 |
|
are from energy scale (Section~\ref{sec:systematics}), luminosity, |
| 38 |
|
and lepton efficiency. Note that these expected SUSY yields |
| 39 |
|
are computed using LO cross-sections, and are therefore underestimated. |
| 40 |
|
|
| 41 |
|
Conveying additional useful information about the results of |
| 42 |
|
a generic ``signature-based'' search such as the one described |
| 43 |
< |
in ths note is a difficult issue. The next paragraph represent |
| 43 |
> |
in this note is a difficult issue. The next paragraph represent |
| 44 |
|
our attempt at doing so. |
| 45 |
|
|
| 46 |
|
Other models of new physics in the dilepton final state |
| 50 |
|
with our upper limit of 4.1 events. The key ingredients |
| 51 |
|
of such studies are the kinematical cuts described |
| 52 |
|
in this note, the lepton efficiencies, and the detector |
| 53 |
< |
responses for SumJetPt and \met/$\sqrt{\rm SumJetPt}$. |
| 53 |
> |
responses for SumJetPt and \met/$\sqrt{\rm SumJetPt}$. These |
| 54 |
> |
quantities have been evaluated with Spring10 MC samples, |
| 55 |
> |
and we are currently checking if any of them change after |
| 56 |
> |
switching to Fall10 MC. |
| 57 |
|
The muon identification efficiency is $\approx 95\%$; |
| 58 |
|
the electron identification efficiency varies from $\approx$ 63\% at |
| 59 |
|
$P_T = 10$ GeV to 91\% for $P_T > 30$ GeV. The isolation |
| 60 |
|
efficiency in top events varies from $\approx 83\%$ (muons) |
| 61 |
|
and $\approx 89\%$ (electrons) at $P_T=10$ GeV to |
| 62 |
< |
$\approx 95\%$ for $P_T>60$ GeV. The average detector |
| 62 |
> |
$\approx 95\%$ for $P_T>60$ GeV. |
| 63 |
> |
{\bf \color{red} THE FOLLOWING QUANTITIES SHOULD BE RECALCULATED AFTER |
| 64 |
> |
WE FIX THE BUGS WITH THE MET IN LM SAMPLES} |
| 65 |
> |
The average detector |
| 66 |
|
responses for SumJetPt and $\met/\sqrt{\rm SumJetPt}$ are |
| 67 |
|
$1.00 \pm 0.05$ and $0.94 \pm 0.05$ respectively, where |
| 68 |
|
the uncertainties are from the jet energy scale uncertainty. |
| 69 |
|
The experimental resolutions on these quantities are 10\% and |
| 70 |
|
14\% respectively. |
| 71 |
|
|
| 62 |
– |
|
| 63 |
– |
|
| 64 |
– |
|
| 72 |
|
To justify the statements in the previous paragraph |
| 73 |
|
about the detector responses, we plot |
| 74 |
|
in Figure~\ref{fig:response} the average response for |
| 77 |
|
signal region. |
| 78 |
|
% (SumJetPt $>$ 300 GeV and \met/$\sqrt{\rm SumJetPt} > 8.5$ |
| 79 |
|
% Gev$^{\frac{1}{2}}$). |
| 80 |
+ |
{\bf \color{red} THE FOLLOWING QUANTITIES SHOULD BE RECALCULATED AFTER |
| 81 |
+ |
WE FIX THE BUGS WITH THE MET IN LM SAMPLES} |
| 82 |
|
We find that the average SumJetPt response |
| 83 |
|
in the Monte Carlo |
| 84 |
|
is very close to one, with an RMS of order 10\% while |
| 106 |
|
The response is defined as the ratio of the reconstructed quantity |
| 107 |
|
to the true quantity in MC. These plots are done using the LM0 |
| 108 |
|
Monte Carlo, but they are not expected to depend strongly on |
| 109 |
< |
the underlying physics.} |
| 109 |
> |
the underlying physics. |
| 110 |
> |
{\bf \color{red} UPDATE AFTER FIXING BUGS WITH LM SAMPLES. } } |
| 111 |
|
\end{center} |
| 112 |
|
\end{figure} |
