| 5 |
|
are generated with the leading order (LO) event generators |
| 6 |
|
{\sl PYTHIA}~\cite{Sjostrand:2003wg}, {\sl ALPGEN} and {\sl COMPHEP}. |
| 7 |
|
To accommodate the next-to-leading (NLO) effects, constant $k$-factors are applied |
| 8 |
< |
except for the signal where a $p_T$-dependence has been taken into account |
| 9 |
< |
and some of the backgrounds, $e.g.$ $t\bar{t}$, $W+jets$, and $Z+jets$ samples, |
| 10 |
< |
officially produced with NLO effects taken into account. |
| 8 |
> |
except for the signal where a $p_T$-dependence has been taken into account. |
| 9 |
|
|
| 10 |
|
The $p_T$-dependent $k$-factor for the signal is estimated using |
| 11 |
|
the NLO cross section calculator {\sl MCFM}~\cite{Campbell:2005}. |
| 28 |
|
\end{equation} |
| 29 |
|
|
| 30 |
|
The LO and NLO distributions of the \Z boson transverse momentum are |
| 31 |
< |
shown in Fig.~\ref{fig:LOvsNLO} with the case of $W^+$ on the left and $W^-$ |
| 34 |
< |
on the right side. The NLO/LO ratio, $k$-factor, is also presented on the figure, |
| 31 |
> |
shown in Fig.~\ref{fig:LOvsNLO}. The NLO/LO ratio, $k$-factor, is also presented on the figure, |
| 32 |
|
and it is increasing with $p_T(\Z)$. We take into account the $p_T$ dependence |
| 33 |
|
by re-weighting the LO Monte Carlo simulation as a function of the $p_T(\Z)$. |
| 34 |
|
% |
| 41 |
|
|
| 42 |
|
\begin{figure}[!bt] |
| 43 |
|
\begin{center} |
| 44 |
< |
\scalebox{0.8}{\includegraphics{figs/LOvsNLOZPtWminuns.eps}\includegraphics{figs/LOvsNLOZPtWplus.eps}} |
| 45 |
< |
\caption{$p_T(Z)$ distribution for LO (solid black histogram) and NLO (dashed black histogram) |
| 49 |
< |
in $W^-\Z$ events (left) and $W^+\Z$ events (right). The ratio NLO/LO is also given as a red |
| 50 |
< |
solid line. |
| 51 |
< |
} |
| 44 |
> |
% \scalebox{0.8}{\includegraphics{figs/k_faktor_for_Note.eps}} |
| 45 |
> |
\caption{Top plot: comparison of $p_T(Z)$ distributions for NLO and LO; bottom plot: k factor } |
| 46 |
|
\label{fig:LOvsNLO} |
| 47 |
|
\end{center} |
| 48 |
|
\end{figure} |
| 98 |
|
generator. |
| 99 |
|
\item $Z^0\gamma$: this process is calculated with {\sl PYTHIA}. |
| 100 |
|
\end{itemize} |
| 101 |
+ |
The background sources that have \Z bosons described above are simulated with the |
| 102 |
+ |
contribution from the virtual photon. |
| 103 |
|
|
| 104 |
|
All the samples we use in this study are a part of the CSA07 production and |
| 105 |
|
are generated using $\mathrm{CMSSW}\_1\_4_\_6$ using the full {\sl GEANT} |
