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\documentclass[12pt,a4paper]{report}
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\usepackage{graphicx}
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\usepackage{textcomp}
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\usepackage{amsmath,amssymb}
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\usepackage{color,multirow,rotating}
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\begin{document}
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\begin{itemize}
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\item \textbf{Do you understand the factor 2 increase in background Z+jets in 2e1mu channel compare to 3mu channel?}\\
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We are trying to fully understand the behaviour (trying to obtain an
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event display but as we have to dig the chowder soup [26 Millions of
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events] this can take time), but by asking that the 3 letpons are
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isolated to each others solve the issue. The fake muon is indeed
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within DeltaR of 0.1 around one of the two electrons making the Z at
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generator level.
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\item \textbf{Why the PDF systematics are only considered for significance (should be the opposite)?}\\
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The PDF systematics should indeed also be considered for the cross section measurement and we added
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vuko |
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them to the list of uncertainties affecting the cross section. It affects it through the signal acceptance
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which may vary for different PDF assumptions. PDF uncertainties are not relevant for the signal significance
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we will quote one day on real data, but they are however relevant for the expected significance we quote
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in this analysis. The estimated significance depends on the number of expected
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signal events, which depend on the WZ cross section. The PDF uncertainties on the cross section have
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been determined at the PTDR time by varying the PDF within the range allowed by the errors of the PDF
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fit (to HERA data).
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\item \textbf{What are the PDF systematics for ZZ background? [mainly for 3mu channel]}\\
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We are using the systematics derived in note AN-2006/055 which are 6.4\%.
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\item \textbf{Does the cross section used for signal include the gamma*?}\\
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The response is complex: the signal simulated by Pythia does not include
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the $\gamma^*$ but the k-factor which has been used to go from LO to
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NLO has been computed via MCFM including $\gamma^*$ (NLO with $\gamma^*$ / LO with $\gamma^*$).
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\item \textbf{Does reconstruction efficiency (Z) depend on pt(Z) ?}\\
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Indeed a bit, so we have applied a k-factor dependant on pt(Z).
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\item \textbf{Are you sure to not have a double counting between $Zb\bar{b}$ background and $Z+jets$?}\\
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Yes, please see the hypernews message:\\
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$https://hypernews.cern.ch/HyperNews/CMS/get/alpgen/83/1.html$
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\item \textbf{Can you confirm that gamma* is included in Zbb and ZZ Monte Carlo and that cross section are correctly calculated?}\\
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For $ZZ$, the production as been done with a m(gamma*) $>$ 12 GeV and for
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beaucero |
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$Zb\bar{b}$ m(gamma*)$>$40 GeV. Please see the webpage:
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$http://cmsdoc.cern.ch/\sim anikiten/cms\-higgs/sm\_cross\-sections.txt$ for
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$ZZ$ and the CMSNote AN 2008/020 for $Zb\bar{b}$ background.
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\item \textbf{Can you confirm that gamma* is included in $Z+jets$ samples?}\\
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beaucero |
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Yes the production has been done within: 40 GeV$<$M(z/gamma*)$<$200GeV
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please see the note:IN 2007/031.
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beaucero |
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\item \textbf{Can you improve signal over background by adding a cut on MET?}\\
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We have studied the possibility but we obtain a better significance by
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applying a cut on transverse mass of W candidate ($>$50 GeV). In the
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analysis we are now considering such cuts. The studies of the
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different angle proposed have been also performed but the transverse
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mass remain the best variable. DO YOU HAVE PLOTS?
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beaucero |
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\item \textbf{Produce Event yield table and mass plot with MET$>$20}\\
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vuko |
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We have updated the note but with a transverse mass cut at 50 GeV.
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vuko |
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\item \textbf{Redo all plots with 300pb$^{-1}$, produce event yields table with errors}\\
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Done in the note
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\item \textbf{Please check the quality of the fit of figure 11?}\\
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Done please see below [M(W)$>$50 GeV has been applied]
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\begin{figure}[!bp]
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\begin{center}
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\scalebox{0.4}{\includegraphics{FitTight3eErrors.eps}}
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\caption{The invariant mass distribution of the $Z$ boson candidate that is fitted to a signal
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parameterized as a Gaussian function convoluted with a Breit-Wigner function and
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a background, parameterized as a straight line.}
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\label{fig:ZFit}
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\end{center}
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\end{figure}
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\item \textbf{Please developp the way systematics will be evaluated}\\
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beaucero |
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We have added: (Bibliography is done in the note)\\
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vuko |
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\begin{itemize}
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\item {\it Trigger}: [...] From the current analysis of
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beaucero |
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$Z\rightarrow l^+l^-$ in CMS~\cite{Zmumu}~\cite{Zee}, the number of Z
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events is estimated of the order of 50k per 100pb$^{-1}$ of data
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analysed. To determine the trigger efficiency ``tag-and-probe''
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beaucero |
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method~\cite{TP} will be used.
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\item {\it Reconstruction}: The
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mismeasurement of the charge is of the order of 2\% in CMSSW\_1\_6\_7
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release for electron. The estimation of the fraction with data will be
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done by looking at the Z peak without opposite charge
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requirement. Then number of events within the Z mass windows asking
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for two leptons of same sign will give us a estimate of the fraction
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of mismeasure sign leptons.
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beaucero |
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\item {\it Lepton identification}:The leptons
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scale will be established using the Z mass peak.
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vuko |
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\item {\it PDF uncertainties}: see response about PDF's above
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\end{itemize}
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vuko |
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\item \textbf{Write a section on the pseudo-experiment and start the plot at 100pb$^-1$}\\
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To estimate the amount of data necessary to claim an evidence or observation
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of the WZ signal, we perform 200,000 pseudoexperiements for data for a given
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value of data that is varied from 40 to 500 pb$^{-1}$. For each pseudoexperiment
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vuko |
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we use Poisson statistics to estimate the expected number of events for
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signal and for each background sources separately, for each signature channel.
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The mean of the expected number of events is varied using Gaussian statistic
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using systematic uncertainties given in Table~\ref{tab:FullSys}. The significance of the
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signal in each pseudo-experiment is calculated using the likelihood ratio
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\begin{equation}
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\label{eq:sl}
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S_L=\sqrt{2\ln Q},\ Q=\biggl( 1+\frac{N_S}{N_B}\biggr)^{N_S+N_B}e^{-N_S},
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\end{equation}
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where $N_S$ and $N_B$ are the expected number of signal and background
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events observed in the four signatures of the analysis, respectively. By summing
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signal and background together, we assume no correlation between the signature
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channels, which result in a conservative estimation of the sensitivity reach.
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vuko |
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The obtained $S_L$ distribution is fitted with Gaussian function to obtain the mean
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and resolution width, which would correspond to the most probable value of $S_L$
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and its uncertainty for a given value of integrated luminosity. The 68\% and 95\%
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CL bands are $\pm 1\sigma$ and $\pm 1.96\sigma$ bands around the mean value
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of the $S_L$ respectively. To estimate the effect of the systematic uncertainty in
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this estimation, we double all the systematic uncertainties and re-calculate the
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68\% and 95\% CL bands. The results for the sensitivity of the analysis without
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requirements on the $W$ boson transverse mass are given in Fig.~\ref{fig:sl_full}.
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5$\sigma$ significance of the WZ signal can be established with data size between
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50 and 300 pb$^{-1}$ of integrated luminosity at 95\% CL.
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\end{itemize}
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\end{document}
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