1 / 19

AA->HH Study Event generation & Analysis of AA->4b BG

AA->HH Study Event generation & Analysis of AA->4b BG. Shin-ichi Kawada (AdSM, Hiroshima University). Outline. Introduction Previous results Today’s topic --- AA->4b BG Event generation Analysis Summary & Next plan. Introduction.

Download Presentation

AA->HH Study Event generation & Analysis of AA->4b BG

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. AA->HH StudyEvent generation & Analysis ofAA->4b BG Shin-ichi Kawada (AdSM, Hiroshima University) 21st General Meeting @ KEK (2011/7/16)

  2. Outline • Introduction • Previous results • Today’s topic --- AA->4b BG • Event generation • Analysis • Summary & Next plan 21st General Meeting @ KEK (2011/7/16)

  3. Introduction • Photon Linear Collider (PLC) has been proposed as one of the options of ILC. • It is expected that we can observe the Higgs self-coupling in PLC. • Feasibility study of Higgs pair creation in PLC is needed. 21st General Meeting @ KEK (2011/7/16)

  4. About PLC ILC : e+ e- collision PLC : gamma gamma collision Electrons Backward Compton scattering gamma-gamma collision 21st General Meeting @ KEK (2011/7/16)

  5. Reaction in gamma-gamma collision • Signal : AA->HH->4b • Many backgrounds • AA->WW, ZZ, 4b, etc… • Analysis of background reduction is necessary. • We assumed that Higgs mass equals to 120GeV in this study. 4b = b b-bar b b-bar 21st General Meeting @ KEK (2011/7/16)

  6. Previous results (1) • Main backgrounds • AA->WW (~11.6pb, 1.5*107 events/year) • AA->ZZ (~9.42fb, 1.2*104 events/year) • Analysis with Neural Network • We can observe Higgs pair creation if we can develop good b-tagging method and jet clustering. 21st General Meeting @ KEK (2011/7/16)

  7. Previous results (2) • Other background --- AA->4b • cross-section = 109fb (with luminosity) • ~ 1.4*105 events/year • need the detector simulation & analysis 21st General Meeting @ KEK (2011/7/16)

  8. Topic (1) : Event generation of AA->4b • Event generator : GRACE, BASES, SPRING • Cut at the BASES level • (2-jet invariant mass) < 15 GeV were cut • cross-section = 46.6fb • ~6*104 events/year • Detector simulation : JSFReadParton • Two types of AA->4b events were generated • optimistic 4b • pessimistic 4b 21st General Meeting @ KEK (2011/7/16)

  9. Event type of AA->4b optimistic event pessimistic event γ b γ b b-bar b-bar b b γ b-bar γ b-bar : color string 21st General Meeting @ KEK (2011/7/16)

  10. Topic (2) : Analysis of AA->4b reduction table m1, m2 : reconstructed particle mass σ2j : resolution evis : visible energy Pl : longitudinal momentum |csjmax| : largest |cosθ| of jet input these data to neural network (NN) 21st General Meeting @ KEK (2011/7/16)

  11. Input parameters signal 4b_pes χH2 χZ2 χA2 transverse momentum longitudinal momentum 21st General Meeting @ KEK (2011/7/16)

  12. Input parameters signal 4b_pes # of b-flavor jet (nsig=3.5, noffv=2) # of tracks # of b-flavor jet (nsig=3.5, noffv=1) visible energy ycut value of jet clustering 21st General Meeting @ KEK (2011/7/16)

  13. Input parameters signal 4b_pes thrust sphericity aplanarity Y-value 21st General Meeting @ KEK (2011/7/16)

  14. Result not bad, but not enough 21st General Meeting @ KEK (2011/7/16)

  15. Discussion • Use other useful parameter • cosθof jet (cosθof 2-jet) • event shape • more tight cuts & input to NN • Jet pairing • choose the pair of least χH2, then get the variables • choose the pair of least χA2, then get the variables • compare these variables, and try to cut them or input to NN. 21st General Meeting @ KEK (2011/7/16)

  16. Summary & Next plan • Event generation with SPRING & detector simulation of AA->4b BG has been finished. • Reduction of AA->4b BG is not bad, but not enough. • Other parameter (cosθ of jet, event shape) would be useful.  I will check. • Compare variables which the pair of least χH2 and pair of least χA2 , and try to cut / input to NN. 21st General Meeting @ KEK (2011/7/16)

  17. Backup slides 21st General Meeting @ KEK (2011/7/16)

  18. pre-selection • Lorentz factor of 2-jet β2j > 0.05 • |cosθ2j| < 0.99 • θ : angle between beam axis and 2-jet • nbj >= 3 • nbj : # of b-flavor jets with nsig = 3.0 & noffv = 1 • nbtj>= 2 • nbtj : # of b-flavor jets with nsig = 3.0 & noffv = 2 21st General Meeting @ KEK (2011/7/16)

  19. significance # of generated HH = 5*104 # of generated 4b = 1*106 80 : 5year*16events/year (signal generation) 3*105 : 5year*6*104events/year (4b BG generation) 21st General Meeting @ KEK (2011/7/16)

More Related