| 14 |
|
region, |
| 15 |
|
for electrons and muons separately. |
| 16 |
|
|
| 17 |
< |
The choice to normalizing to the peak region of $M_T$ has the |
| 17 |
> |
The choice to normalize to the peak region of $M_T$ has the |
| 18 |
|
advantage that some uncertainties, e.g., luminosity, cancel. |
| 19 |
|
It does however introduce complications because it couples |
| 20 |
|
some of the uncertainties in non-trivial ways. For example, |
| 39 |
|
These vary between 2\% and 20\%, depending on the signal region |
| 40 |
|
(different |
| 41 |
|
signal regions have different \met\ requirements, thus they also have |
| 42 |
< |
different $M_T$ regions used as control. |
| 42 |
> |
different $M_T$ regions used as control). |
| 43 |
|
Since |
| 44 |
|
the major backgrounds, eg, $t\bar{t}$ are normalized to the peak regions, this |
| 45 |
|
fractional uncertainty is pretty much carried through all the way to |
| 60 |
|
If the $M_T$ peak region is not well modelled, this would introduce an |
| 61 |
|
uncertainty. |
| 62 |
|
|
| 63 |
< |
We have tested this possibility by recalculating the post veto scale factors for a different |
| 63 |
> |
We have tested this possibility by recalculating the post-veto scale factors for a different |
| 64 |
|
choice |
| 65 |
|
of $M_T$ peak region ($40 < M_T < 100$ GeV instead of the default |
| 66 |
< |
$50 < M_T < 80$ GeV. This is shown in Table~\ref{tab:mtpeaksf2}. |
| 66 |
> |
$50 < M_T < 80$ GeV). This is shown in Table~\ref{tab:mtpeaksf2}. |
| 67 |
|
The two results for the scale factors are very compatible. |
| 68 |
|
We do not take any systematic uncertainty for this possible effect. |
| 69 |
|
|
| 113 |
|
\end{table} |
| 114 |
|
|
| 115 |
|
|
| 116 |
< |
\subsection{Uncertainty on the Wjets cross-section and the rare MC cross-sections} |
| 116 |
> |
\subsection{Uncertainty on the \wjets\ cross-section and the rare MC cross-sections} |
| 117 |
|
These are taken as 50\%, uncorrelated. |
| 118 |
|
The primary effect is to introduce a 50\% |
| 119 |
|
uncertainty |
| 143 |
|
dilepton MC is rescaled by the factors $K_3$ and $K_4$ to make |
| 144 |
|
it agree with the data. The 3\% uncertainties on $K_3$ and $K_4$ |
| 145 |
|
comes from data/MC statistics. This |
| 146 |
< |
result directly in a 3\% uncertainty on the dilepton background, which is by far |
| 146 |
> |
results directly in a 3\% uncertainty on the dilepton background, which is by far |
| 147 |
|
the most important one. |
| 148 |
|
|
| 149 |
|
\subsection{Uncertainty from MC statistics} |
| 167 |
|
|
| 168 |
|
\begin{itemize} |
| 169 |
|
\item Top mass: The alternative values for the top mass differ |
| 170 |
< |
from the central value by $5~\GeV$: $m_{\mathrm{top}} = 178.5~\GeV$ and $m_{\mathrm{top}} |
| 170 |
> |
from the central value by $6~\GeV$: $m_{\mathrm{top}} = 178.5~\GeV$ and $m_{\mathrm{top}} |
| 171 |
|
= 166.5~\GeV$. |
| 172 |
|
\item Jet-parton matching scale: This corresponds to variations in the |
| 173 |
|
scale at which the Matrix Element partons from Madgraph are matched |
| 186 |
|
\item The PDF uncertainty is estimated following the PDF4LHC |
| 187 |
|
recommendations. The events are reweighted using alternative |
| 188 |
|
PDF sets for CT10 and MSTW2008 and the uncertainties for each are derived using the |
| 189 |
< |
alternative eigenvector variations and the ``master equation''. In |
| 190 |
< |
addition, the NNPDF2.1 set with 100 replicas. The central value is |
| 189 |
> |
alternative eigenvector variations and the ``master equation''. |
| 190 |
> |
The NNPDF2.1 set with 100 replicas is also used. The central value is |
| 191 |
|
determined from the mean and the uncertainty is derived from the |
| 192 |
|
$1\sigma$ range. The overall uncertainty is derived from the envelope of the |
| 193 |
|
alternative predictions and their uncertainties. |
