EGamma_ElectronTrackingValidation/docs/presentations/2017_12_13/main.tex

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\begin{document}

\title[e Reco. Validation]{Off-line Electron Seeding Validation \-- Update}
\author[C. Fangmeier]{\textbf{Caleb Fangmeier} \\ Ilya Kravchenko,  Greg Snow}
\institute[UNL]{University of Nebraska \-- Lincoln}
\date{Joint ECAL/EGM Meeting | December 13, 2017}

\titlegraphic{%
\begin{figure}
  \includegraphics[width=1in]{CMSlogo.png}\hspace{0.75in}\includegraphics[width=1in]{nebraska-n.png}
\end{figure}
}

\begin{frame}[plain]
  \titlepage%
\end{frame}

\begin{frame}{Introduction}
  \begin{itemize}
    \item Our goal is to study \textbf{seeding} for the \textbf{off-line} GSF tracking with the \textbf{new pixel detector}.
    \item Specifically, we want to optimize the new pixel-matching scheme from HLT for use in off-line reconstruction.
    \item Since last update\footnote{https://indico.cern.ch/event/662751/contributions/2778076/attachments/1562070/2460731/main.pdf},
    \begin{itemize}
        \item Created sets of nTuples to compare/contrast seeding with new/old scheme.
        \item Dataset: \\
          {\tiny \vspace{0.05in}\hspace{-0.2in}\texttt{/ZToEE\_NNPDF30\_13TeV-powheg\_M\_120\_200/
              \vspace{-0.05in}\hspace{-0.2in}RunIISummer17DRStdmix-NZSFlatPU28to62\_92X\_upgrade2017\_realistic\_v10-v1/GEN-SIM-RAW}}\vspace{0.05in}
        \item Ntuples on Nebraska T2 (happy to share with interested parties!)
    \end{itemize}
  \item This Talk:
    \begin{itemize}
      \item Show performance comparisons between new and old seeding schemes
      \item Show correlations between performance and detector geometry
      \item Next steps
    \end{itemize}
  \end{itemize}
\end{frame}


\begin{frame}
  First, some definitions
  \begin{itemize}
    \item \textbf{Sim-Track \--} A track from a simulated electron originating from the luminous region of CMS (beam-spot +- 5$\sigma$)
    \item \textbf{ECAL-Driven Seed \--} A seed created via a matching procedure between Super-Clusters and General Tracking Seeds (Either from \texttt{ElectronSeedProducer} or \texttt{ElectronNHitSeedProducer})
    \item \textbf{GSF Track \--} A track from GSF-Tracking resulting from an \textbf{ECAL-Driven Seed}
    \item \textbf{Seeding Efficiency \--} The fraction of \textbf{Sim-Tracks} that have a matching \textbf{ECAL-Driven Seed} (based on simhit-rechit linkage)
    \item \textbf{GSF Tracking Efficiency \--} The fraction of \textbf{Sim-Tracks} that have a matching \textbf{GSF Track} (again, based on simhit-rechit linkage)
    \item \textbf{ECAL-Driven Seed Purity \--} The fraction of \textbf{ECAL-Driven Seeds} that have a matching \textbf{Sim-Track}
    \item \textbf{GSF Tracking Purity \--} The fraction of \textbf{GSF Tracks} that have a matching \textbf{Sim-Track}
  \end{itemize}
\end{frame}

\begin{frame}{ECAL-Driven Seeding Efficiency}
  \begin{columns}
  \begin{column}{0.45\textwidth}
    \begin{itemize}
      \item In general, performance is similar between old and new seeding scheme
      \item Some early drop-off in efficiency at high eta
      \item Note the drop in efficiency around $\eta\approx 1.4$. (see next slide)
    \end{itemize}
  \end{column}
  \begin{column}{0.55\textwidth}
    \begin{figure}
      \includegraphics[width=\textwidth]{./figures/live/ECAL-Driven_Seeding_Efficiency.png}
    \end{figure}
  \end{column}
  \end{columns}
\end{frame}

\begin{frame}{Number of Pixel Layers vs. $\eta$}
  \begin{columns}
  \begin{column}{0.45\textwidth}
    \begin{itemize}
      \item Expected number of layers with hits is flat just under 4 for $|\eta|<1.2$, but
      \item Drops significantly at the boundary between BPIX and FPIX
      \item However, at $|\eta|=2$, it peaks since the track could pass through BPIX L1-L2 \emph{and} FPIX L1-L3.
    \end{itemize}
  \end{column}
  \begin{column}{0.55\textwidth}
    \vspace{-0.25in}
    \begin{figure}
      \includegraphics[width=0.9\textwidth]{./figures/live/Hits.png}
    \end{figure}
    \vspace{-0.15in}
    \begin{figure}
      \includegraphics[width=0.7\textwidth]{./diagrams/phase2_tracker.jpg}
    \end{figure}
  \end{column}
  \end{columns}
\end{frame}

\begin{frame}{ECAL-Driven Seeding Purity}
  \begin{columns}
  \begin{column}{0.45\textwidth}
    \begin{itemize}
      \item Similar performance in forward region, but new seeding suffers from low purity in the barrel, and especially in the transition region
      \item Kinematic quantities here are from the seeds (based on some basic fitting), so likely worse resolution than from the GSF Tracks.
    \end{itemize}
  \end{column}
  \begin{column}{0.55\textwidth}
    \begin{figure}
      \includegraphics[width=\textwidth]{./figures/live/ECAL-Driven_Seed_Purity.png}
    \end{figure}
  \end{column}
  \end{columns}
\end{frame}

\begin{frame}{GSF Tracking Efficiency}
  \begin{columns}
  \begin{column}{0.45\textwidth}
    \begin{itemize}
      \item Again, similar performance between seeding strategies, although new is slightly worse
      \item Note that both strategies share a performance dip in the BPIX-FPIX transition region
    \end{itemize}
  \end{column}
  \begin{column}{0.55\textwidth}
    \begin{figure}
      \includegraphics[width=\textwidth]{./figures/live/GSF_Tracking_Efficiency.png}
    \end{figure}
  \end{column}
  \end{columns}
\end{frame}


\begin{frame}{GSF Tracking Purity}
  \begin{columns}
  \begin{column}{0.45\textwidth}
    \begin{itemize}
      \item Similar performance, \textit{but}
      \item Strangely, it seems that the purity of the GSF-Tracks is worse than the ECAL-Driven Seeds that produced them!
      \item Which doesn't seem right... Needs further investigation.
    \end{itemize}
  \end{column}
  \begin{column}{0.55\textwidth}
    \begin{figure}
      \includegraphics[width=\textwidth]{./figures/live/GSF_Track_Purity.png}
    \end{figure}
  \end{column}
  \end{columns}
\end{frame}

\begin{frame}{Outlook}
  \begin{itemize}
    \item Targets for immediate investigation
    \begin{itemize}
      \item Sources of impurity in ECAL-Driven Seeds and GSF-Tracks (Pile-up? Conversions? Will be relatively straight-forward w/ truth info)
      \item Reasons for GSF-Tracks being less pure than their associated ECAL-Driven Hits
      \item Ensure that the simhit-rechit matching procedure isn't biasing these results based on the number of available hits
    \end{itemize}
    \item After that
    \begin{itemize}
      \item Determine method to optimize window sizing, trying to improve, ideally, both tracking efficiency and purity (Not so easy. Many knobs to adjust!)
      \item Suggestions?
    \end{itemize}
  \end{itemize}
  \vspace{1.5in}
\end{frame}

\begin{frame}
  \begin{center}
    {\Huge BACKUP}
  \end{center}
\end{frame}

\begin{frame}{Triplet Electron Seeding \-- Setup}
  \begin{columns}
  \begin{column}{0.45\textwidth}
    \begin{itemize}
      \item Begin with ECAL super cluster and beam spot
    \end{itemize}
  \end{column}
  \begin{column}{0.55\textwidth}
    \begin{figure}
      \includegraphics[width=\textwidth]{diagrams/seeding_base.png}
    \end{figure}
  \end{column}
  \end{columns}
\end{frame}

\begin{frame}{Triplet Electron Seeding - Introduce Seed}
  \begin{columns}
  \begin{column}{0.45\textwidth}
    \begin{itemize}
      \item Now, examine, one-by-one seeds from general tracking*
      \item Note that we do not look at all hits in an event, but rather rely on general tracking to identify seeds.
    \end{itemize}
    \vspace{0.1in}
    \hline
    \vspace{0.1in}
    {\footnotesize *initialStepSeeds, highPtTripletStepSeeds, mixedTripletStepSeeds, pixelLessStepSeeds, tripletElectronSeeds, pixelPairElectronSeeds, stripPairElectronSeeds}
  \end{column}
  \begin{column}{0.55\textwidth}
    \begin{figure}
      \includegraphics[width=\textwidth]{diagrams/seeding_step1.png}
    \end{figure}
  \end{column}
  \end{columns}
\end{frame}

\begin{frame}{Triplet Electron Seeding - Match First Hit}
  \begin{columns}
  \begin{column}{0.5\textwidth}
    \begin{itemize}
      \item Using the beam spot, the SC position, and SC energy, propagate a path through the pixels.
      \item Next, require the first hit to be within a $\delta\phi$ and $\delta z$ window. ($\delta\phi$ and $\delta R$ for FPIX)
      \item $\delta z$ window for first hit is huge as SC and beam spot positions give very little information about $z$.
    \end{itemize}
  \end{column}
  \begin{column}{0.5\textwidth}
    \begin{figure}
      \includegraphics[width=\textwidth]{diagrams/seeding_step2.png}
    \end{figure}
  \end{column}
  \end{columns}
\end{frame}

\begin{frame}{Triplet Electron Seeding - Extrapolate Vertex}
  \begin{columns}
  \begin{column}{0.45\textwidth}
    \begin{itemize}
      \item Once we have a matched hit, use it with the SC position, to find the vertex z.
      \item Vertex x and y are still the beam spot's.
      \item Just a simple linear extrapolation.
    \end{itemize}
  \end{column}
  \begin{column}{0.55\textwidth}
    \begin{figure}
      \includegraphics[width=\textwidth]{diagrams/vertex_z.png}
    \end{figure}
  \end{column}
  \end{columns}
\end{frame}

\begin{frame}{Triplet Electron Seeding - Match Other Hits}
  \begin{columns}
  \begin{column}{0.45\textwidth}
    \begin{itemize}
      \item Now forget the SC position, and propagate a new track based on the vertex and first hit positions, and the SC energy.
      \item Progress one-by-one through the remaining hits in the seed and require each one fit within a specified window around the track.
      \item Quit when all hits are matched, or a hit falls outside the window. No skipping is allowed.
      \item However, \emph{layer} skipping is not ruled out if the original seed is missing a hit in a layer
    \end{itemize}
  \end{column}
  \begin{column}{0.55\textwidth}
    \begin{figure}
      \includegraphics[width=\textwidth]{diagrams/seeding_step3.png}
    \end{figure}
  \end{column}
  \end{columns}
\end{frame}

\begin{frame}{Triplet Electron Seeding - Window Sizes}
  \begin{columns}
  \begin{column}{0.55\textwidth}
    \begin{itemize}
      \item The $\delta\phi$ and $\delta R/z$ windows for each hit are defined using three parameters.
        \begin{itemize}
          \item \texttt{highEt}
          \item \texttt{highEtThreshold}
          \item \texttt{lowEtGradient}
        \end{itemize}
      \item From these, the window size is calculated as \\
        $\texttt{highEt} + \min(0,\texttt{Et}-\texttt{highEtThreshold})*\texttt{lowEtGradient}$.
      \item For the first hit, these parameters for the $\delta \phi$ window are,
        \begin{itemize}
          \item $\texttt{highEt}=0.05$
          \item $\texttt{highEtThreshold}=20$
          \item $\texttt{lowEtGradient}=-0.002$
        \end{itemize}
      \item For the first hit, these parameters for the $\delta \phi$ window are,
    \end{itemize}
  \end{column}
  \begin{column}{0.45\textwidth}
    \begin{figure}
      \includegraphics[width=\textwidth]{figures/dphi1_max.png}
    \end{figure}
  \end{column}
  \end{columns}
  \vspace{0.1in} \hrule \vspace{0.1in}
  These parameters can be specified for each successive hit, and in bins of $\eta$, so optimization is a challenge!
\end{frame}

\begin{frame}{Triplet Electron Seeding - Handle Missing Hits}
  \begin{columns}
  \begin{column}{0.45\textwidth}
    \begin{itemize}
      \item Finally, calculate the expected number of hits based on the number of working pixel modules the track passes through.
      \item Require exact$^1$ number of matched hits depending on the expected number of hits.
        \begin{itemize}
          \item If $N_{\textrm{exp}}=4$, require $N_{\textrm{match}}=3$
          \item If $N_{\textrm{exp}}<4$, require $N_{\textrm{match}}=2$
        \end{itemize}
      \item If the seed passes all requirements, all information, including
        \begin{itemize}
          \item Super cluster
          \item Original Seed
          \item Residuals (For both charge hypotheses)
        \end{itemize}
        are wrapped up and sent downstream to GSF tracking
    \end{itemize}
  \end{column}
  \begin{column}{0.55\textwidth}
    \begin{figure}
      \includegraphics[width=\textwidth]{diagrams/seeding_step4.png}
    \end{figure}
  \end{column}
  \end{columns}
  \vspace{0.1in} \hrule \vspace{0.1in}
  {\footnotesize $^1$Exact, rather than minimum to deal with duplicate seeds in input collection. Could switch to minimum with offline cross-cleaned seeds.}
\end{frame}

\end{document}