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h 1 → a 1 a 1 → µ + µ - τ + τ - in NMSSM model with tau decaying hadronically

h 1 → a 1 a 1 → µ + µ - τ + τ - in NMSSM model with tau decaying hadronically By: Hou Keong(Tim) Lou Advisor: Chris Potter. Signature?. a 1 can decay into 2g, 2l, 2j For 1fb -1 data* (m a1 = 5GeV and m h1 = 100GeV) : 4µ 1.3 events 2µ 2g (2c) 12.8 events 2µ 2τ 205 events

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h 1 → a 1 a 1 → µ + µ - τ + τ - in NMSSM model with tau decaying hadronically

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  1. h1 → a1a1 → µ+µ-τ+τ- in NMSSM model with tau decaying hadronically By: Hou Keong(Tim) Lou Advisor: Chris Potter

  2. Signature? • a1 can decay into 2g, 2l, 2j • For 1fb-1data* (ma1 = 5GeV and mh1 = 100GeV) : • 4µ 1.3 events • 2µ 2g (2c) 12.8 events • 2µ 2τ 205 events • 4τ 32800 events • 2 µ low mass resonance (between 2τ and 2b, 4~8 GeV) * a1 decay branching ratios obtained from arXiv:0811.3537v1, by R. Dermisek and J. Gunion ** h1 production x-section from SM gluon fusion

  3. The tao of taus • Missing Et: τ lepton number conservation • τ decay modes: • 35% leptonically, 2 neutrinos • 65% Hadronically with 1 neutrino • 50% - 1 prongs (1 pion) → τ jet • 15% - 3 prongs (3 pions) → τ jet

  4. Boost... • Plan of attack: • Assume τ decays into 1 neutrino + jet • Ev at most ~ mτ/2 ~ 1GeV • H → a1 a1 (highly boosted) • Boosted τ → neutrino roughly in the same direction as the jet in lab frame • Colinearity assumption

  5. MC generation • Goal: obtain ~10k events • h1 mass = 100 GeV, a1 mass = 5 GeV • Generated using Pythia + official ATLAS tools • Event generation → detector simulations → digitization → reconstruction → D3PD ntuplization → data for analysis • Currently obtained ~1600 events • Eventually get official production

  6. Plots – and the story goes • Muons:

  7. Tau reconstruction • Two unknowns: • Pz and E of the total missing Et • Assumption: • Collinearity assumption: i.e. the ν's are roughly in the direction of the τ • Mass of jj + neutrinos = mass of µµ (not applied yet) • Simple reconstruction: • Project jj momenta on xy plane • MEt → reconstruct neutrinos momenta on xy plane • Colinearity → Pz of neutrions • Neutrino ~ massless → E

  8. Plots – the ending... for now • Reconstructed Mass

  9. Future goal • Generate more MC samples • Improve neutrino reconstructions—relax colinearity and use muon mass resonance • Consider background: QCD, Z+jets, ZZ, ttbar...etc • Optimize cuts • Consider different final states: µµ gg/cc (no MEt)

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