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ZH (H -> tau tau) Study Current Status

ZH (H -> tau tau) Study Current Status. Shin- ichi Kawada ( AdSM , Hiroshima Univerisity ). AA -> HH paper published !. Phys . Rev. D 85 , 113009. H -> tau tau. first step. CM energy = 250 GeV , M H = 120 GeV /c 2 Signal ( leptonic mode )

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ZH (H -> tau tau) Study Current Status

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  1. ZH (H -> tau tau) StudyCurrent Status Shin-ichi Kawada (AdSM, Hiroshima Univerisity) Asian Physics and Software Meeting (2012/6/29)

  2. AA -> HH paper published ! Phys. Rev. D 85, 113009 Asian Physics and Software Meeting (2012/6/29)

  3. H -> tau tau first step Asian Physics and Software Meeting (2012/6/29) • CM energy = 250 GeV, MH = 120 GeV/c2 • Signal (leptonic mode) • e+e- -> ZH -> (e+e-) (tau+tau-) or (mu+mu-) (tau+tau-)

  4. Possible backgrounds 4 leptons H -> others Asian Physics and Software Meeting (2012/6/29) 4 leptons background H -> others

  5. Event samples Asian Physics and Software Meeting (2012/6/29) • LOI sample • signal: eeH, mumuH(H -> tautau and H -> others are included in this sample file) • BG: 4 leptons • eeee • eemumu • eetautau • mumumumu • mumutautau • tautautautau

  6. Event reconstruction Asian Physics and Software Meeting (2012/6/29) • Step 1: finding isolated leptons • I adopted most energetic positive-charged track and most energetic negative-charged track as the isolated leptons. • Step 2: 2-jet clustering

  7. Event selection (1) Z candidate Asian Physics and Software Meeting (2012/6/29) • Cut 0 (pre-selection) • 1 positive-charged track • 1 negative-charged track • 2-jet

  8. Event selection (2) Cut 1 Asian Physics and Software Meeting (2012/6/29) • In order to separate signal and H -> others. • Cut 1: # of tracks in a jet <= 5 • Cut 2: # of pfos <= 25

  9. Event selection (3) Cut 3 Asian Physics and Software Meeting (2012/6/29) • Cuts for Z candidate • Cut 3: 30 < MZ < 140 • Cut 4: 20 < EZ < 150 • Cut 5: -0.98 < negative < 0.95 • Cut 6: -0.95 < positive< 0.98 • Cut 7: -0.98 < betweenchargedtracks< 0.4

  10. Event selection (4) Cut 8 Asian Physics and Software Meeting (2012/6/29) • Cut 8: 100 < visible energy < 240 • Cut 9: |missmom| < 0.98

  11. Event selection (5) Cut 12 Asian Physics and Software Meeting (2012/6/29) • Cuts for jets (H candidate) and recoil mass • Cut 10: Mjj < 140 • Cut 11: |j| < 0.98 • Cut 12: 115 < recoil mass < 160

  12. Asian Physics and Software Meeting (2012/6/29)

  13. Very preliminary results Asian Physics and Software Meeting (2012/6/29) Signal efficiency = 62.8 % Significance = 6.26 <--> Br(H -> tau tau)/Br(H -> tau tau) = 16 % almost suppressed: eeee (242749 -> 54.26), eemumu (271835 -> 62.88), mumumumu (1698 -> 9.529) remained: eetautau (238089 -> 948.2), mumutautau (3468 -> 405.0), tautautautau (1730 -> 122.0)

  14. Recoil mass distribution (after all cuts) (stacked histogram) signals mumutautau eetautau Asian Physics and Software Meeting (2012/6/29)

  15. Current problems Asian Physics and Software Meeting (2012/6/29) The selection method of isolated lepton is too simple. Optimization is needed. The precision 16 % is not enough. The analysis for qqH is needed.

  16. Summary Asian Physics and Software Meeting (2012/6/29) • Significance = 6.26 (precision = 16 %) • leptonic mode signal (eeH and mumuH)+ 4 leptons BG • signal efficiency = 62.8 % • Need optimization for selecting isolated leptons. • Analysis for qqH (hadronic mode) is needed.

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