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The tau identification strategy described previously can be extended by |
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looking at the different hadronic decay modes of the tau individually. |
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The dominant hadronic decays of taus consist of a one or three charged |
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$\pi^{\pm}$ mesons and up to two $\pi^0$ mesons and are enumerated in |
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< |
table~\ref{table:decay_modes}. Most of these decays proceed through |
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table~\ref{tab:decay_modes}. The majority of these decays proceed through |
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intermediate resonances and each of these decay modes maps directly to a tau |
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final state multiplicity. Each intermediate resonance has a different invariant |
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mass (see figure~\ref{fig:trueInvMass}). The implies that the problem of |
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hadronic tau identification can be re-framed from a global search for collimated |
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hadrons satisfying the tau mass constraint into a ensemble of searches for |
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single production of the different hadronic tau decay resonances. The TaNC |
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algorithm applies this approach using two complimentary techniques: a method to |
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reconstruct the decay mode and an ensemble of neural network classifiers used to |
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discriminant the individual decay modes. |
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mass (see figure~\ref{fig:trueInvMass}). This implies that the problem of |
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hadronic tau identification can be re-framed from a global search for |
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> |
collimated hadrons satisfying the tau mass constraint into a ensemble of |
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searches for single production of the different hadronic tau decay resonances. |
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The Tau Neural Classifier algorithm implements this approach using two |
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complimentary techniques: a method to reconstruct the decay mode and an |
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ensemble of neural network classifiers used to discriminant the individual |
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decay modes. |
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|
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\begin{table} |
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\centering |
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\begin{tabular}{ l c r r } |
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Visible Decay Products & Resonance & Mass (M$e$V/$c^2$) & |
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Fraction~\cite{pdtTauBR} \\ |
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Fraction~\cite{pdg} \\ |
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\hline |
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$\pi^{-}$ & n/a & 135 & 10.9\% \\ |
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$\pi^{-}$ & - & 135 & 10.9\% \\ |
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$\pi^{-}\pi^0$ & $\rho$ & 770 & 25.5\% \\ |
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$\pi^{-}\pi^0\pi^0$ & $a1$ & 1200 & 9.3\% \\ |
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$\pi^{-}\pi^{-}\pi^{+}$ & $a1$ & 1200 & 9.03\% \\ |
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\end{tabular} |
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\label{tab:decay_modes} |
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\caption{Resonances and branching ratios of the dominant hadronic decays of |
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the tau lepton.} |
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the tau lepton. The decay products listed correspond to a negatively |
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charged tau lepton; the table is identical under charge conjugation.} |
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\end{table} |
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|
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\begin{figure}[t] |
