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The first round of $WZ$ analysis was made at the time of PTDR
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Vol. 1~\cite{PTDR2}. At that time, it was shown that a significance of
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5$\sigma$ can be reached with 150 pb$^{-1}$ of integrated
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luminosity by combining electron and muon channels.
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Since that time, electron reconstruction schema underwent through
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major changes. The Kalman Filter tracking algorithm
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has been replaced with Gauss Filter algorithm (GSF) which improved
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electron reconstruction efficiency. Unfortunately, the probability
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of a jet with high electromagnetic content (em-jet) to mimic an electron
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is increased dramatically as well. To compensate for the increase
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in the em-jet misidentification and to improve the robustness of
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electron identification criteria in startup conditions, a new
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electron identification criteria are developed~\cite{EgammaOfficial}.
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The development of the criteria for isolated electrons is currently
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ongoing.
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A first pass on the analysis using the official electron identification criteria
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indicated that the $WZ\rightarrow \ell^+\ell^-e\nu_e$ channel is severely
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dominated by the background from $Z+jet$ process, with jet being
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misidentified as an electron. As a result, 3 electron final state is completely
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saturated by $Z+jet \to 2 e + jet$ process, and it does not contribute
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to a discovery of $WZ$ final state at CMS. In order to improve the
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discovery potential, we study the electron identification criteria
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starting with discriminants used in the official selection and tuning the
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thresholds to suit the $WZ$ analysis needs. We also study the performance
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of different isolation requirements that helps to suppress the copious
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$Z+jet$ background.
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The note is organized as following. The data samples and CMSSW software
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releases are described in Section~\ref{Data}. This section is followed by
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the description of kinematics and acceptance requirements to select $WZ$
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final state in Section~\ref{BasicSelection}. The electron identification discriminants
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and the procedure used to tune the thresholds is given in Section~\ref{Def}.
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The comparison of the newly developed electron identification with the official
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criteria is done in Section~\ref{Results}. We summarize the results in
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Section~\ref{Conclusions}.
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