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Full Simulation (Jupiter/MarlinReco) of Tau-pair/SUSY mode

Full Simulation (Jupiter/MarlinReco) of Tau-pair/SUSY mode. Taikan Suehara ICEPP, The Univ. of Tokyo. Topics/Motivation. Topics Tau-pair SUSY 4-jet mode SUSY smuon mode Motivation Detector optimization Obtain performance of each benchmark mode Compare performance in various geometries

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Full Simulation (Jupiter/MarlinReco) of Tau-pair/SUSY mode

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  1. Full Simulation (Jupiter/MarlinReco) ofTau-pair/SUSY mode Taikan Suehara ICEPP, The Univ. of Tokyo

  2. Topics/Motivation • Topics • Tau-pair • SUSY 4-jet mode • SUSY smuon mode • Motivation • Detector optimization • Obtain performance of each benchmark mode • Compare performance in various geometries • GLD (large, 3T), GLD’ (medium, 3.5T), J4LDC (small, 4T) • Physics • Detection of tau-pair anomalous coupling (Z’ etc.) • SUSY/LHT/scalar particles detection/distinction

  3. SUSY 4-jet-mode

  4. SUSY parameters • Point 1 smuon -> mu x01 • Point 5 neutralino (x02) / chargino • Chargino/neutralino decay to W/Z+LSP

  5. SUSY jet mode • Qqbar 4jet events, 130(chargino),30(neutralino) fb • 500 fb-1 with full simulation • Chargino/neutralino must be separated by identifying daughter W/Z. • Main BG: SM WW -> 4 jets (10000 fb)

  6. Cut statistics (1) • # of SM events becomes comparable to chargino after these cuts.

  7. W/Z mass peak – best combination Cut condition • Same cut asprevious slide • Best-W combinationfor chargino events,Best-Z combinationfor neutralino events(minimum c2 combination, 1s width is set to 5 GeVfor both W and Z) • Peak shift corrected (by adding 0.8 GeV to all jets).

  8. c2 distribution / mass cut

  9. Cut statistics (2) chargino neutralino • BG separation is efficient (see W/Z mass cut rows) • Slightly better BG separation performance in GLD but almost within statistical fluctuations.

  10. Mass fit of chargino/neutralino • SUSY mass is determined by kinematics • Daughter W/Zs have characteristic energy distribution • Fitting function: • For neutralino: erf(left) x erfc(right) • For chargino: erf(left),conbolution of linear and erfc for right • Generator-level energy distributions (by Akiya): Chargino (W) Neutralino (Z)

  11. Chargino MC cut vs nocut Very slight shift (left edge?)

  12. Chargino MC vs Reco Mass cut by 80 GeV W Slightly shifted?

  13. Mass fit of chargino Fitting seems not so bad. Difference in distribution is within statistical fluctuation.

  14. Another fitting • Convolution of 3rd pol and Gaussian • Partly cheated • 1. LSP/chargino mass fixed to input values, fit other 5 parameters • 2. 5 parameters fixed, mass fitted.

  15. Neutralino reco/MC • Flat distribution around the top

  16. Mass fit neutralino Distribution in LDC is slightly broader (worse resolution). Chargino background might not be negligible for lower edge.

  17. SUSY-jet conclusion • Point 5 chargino/neutralino pair is examined. • Mass resolution < 1 GeV can be obtained by 500 fb-1 statistics • SM WW background can be removed efficiently • W/Z separation for chargino/neutralino separation can be effective in current detector geometry.

  18. SUSY lepton mode

  19. Smuon • Smuon : 123 GeV, LSP: 97 GeV • Edge of the energy distribution is sharp enough • More background / muon ID efficiency can be examined.

  20. Smuon – reco - MC • No difference.

  21. SUSY-smuon conclusion • Point 1 smuon analysis was performed. • Clear edge can be seen

  22. Tau-pair mode

  23. Tau-pair events • Event characteristics • Sqrt(s) = 500 GeV, including ISR/FSR • 2 jets,1 or 3 prongs/jet, very condensing(taus in 500 GeV beam are highly boosted) • Cross section is large, ~2.3 pb-1 • Observables -s, total and differential cross section • AFB, forward-backword asymmetry • Apol, polarization asymmetry (paticularly in polarized beams) • Background and Statistics • Background: bhabha (34000 pb), gg->tt (1500 pb) • Signal: 20 fb-1 (~46000 events) • Bhabha: 0.2 fb-1 preselected full-simulated events • gg->tt 0.7 fb-1 generator info Typical event

  24. Decay modes in Apol analysis

  25. Analysis flow Pandora PFA PFO particles TaJet jet finder Jets AFB 1+1 jets cut Back to back cut SM veto cuts Apol (t->pn) No r reconstruction Neutral particle 8.6% Yes 1 prong cut Lepton veto Energy cut p0 reconstruction 7.0% Apol (t->rn)

  26. Background suppression • Bhabha and ggtt background can be effectively suppressed • Statistics in Jupiter will be improved to 20fb-1by Cambridge

  27. Tau AFB result SM calculation (Red: left, Blue: right)

  28. Rho and pi0 reconstruction • Clear difference • LDC’ best • Due to granularity? • GLD next • J4LDC worst

  29. Cut efficiency • Worse tau->rhonu efficiency in J4LDC:due to the worse reconstruction of pi0 • Need to be checked in more detail.(esp. for LDC’) • eR efficiency in rhonu mode is worse:due to low energy cut

  30. t -> pn Apol Need to check MC distribution w/wo cut

  31. t -> rn, r->pp Apol • Calculation of pol. value is complicated (not yet). • Difference between eL/eR can be seen. • Difference between geometries can be seen,need to check the reason.

  32. Theoretical angular distribution • Separation of cos(theta) ~ 0.6 is the best?

  33. Another method • Combined information of tau to rhonu andrho to pipi decay can be used in this method. Physics Letters B, 235 (1990) 198

  34. Tau-pair conclusion • AFB and Apol of tau-pair events are analyzed. • Effective suppression of background can be achievable. • AFB can be obtained with < 0.2% error in 500 fb-1 • Apol is obtained by both t->pn and t->rn, r->pp modes • Need more work for t->rn mode • Difference of Apol between eL and eR can be seen • Apol can be obtained with < 1% error in 500 fb-1

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