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VV scattering in P-TDR (CHAPTER 13.2 Vol 2.2)

VV scattering in P-TDR (CHAPTER 13.2 Vol 2.2). A simple summary of what we intend to put in our chapter. The TORINO group : E.Accomando, A.Ballestrero, R.Bellan,. S.Bolognesi , G.Cerminara, E.Maina, C.Mariotti. CPTweek / PRSsession 10/31/05. Sara Bolognesi (TORINO). The chapter structure.

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VV scattering in P-TDR (CHAPTER 13.2 Vol 2.2)

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  1. VV scattering in P-TDR (CHAPTER 13.2 Vol 2.2) A simple summary of what we intend to put in our chapter The TORINO group: E.Accomando, A.Ballestrero, R.Bellan, S.Bolognesi, G.Cerminara, E.Maina, C.Mariotti CPTweek / PRSsession 10/31/05 Sara Bolognesi (TORINO)

  2. The chapter structure would it be better not to separate the “no Higgs” and the “heavy-mass Higgs” case? 13.2 Heavy Higgs boson and VV scattering 13.2.1 WW scattering in the absence of Higgs boson 13.2.1.1 Semileptonic final state since in our analysis we study both the cases 13.2.1.2 Signal definition and simulation 13.2.1.2.1 Six fermions final state processes 13.2.1.2.2 VV-fusion signal selection at already done partonic level: qq -> qqVV -> qqVW -> qqqqmn qq -> qqVV -> qqVZ -> qqqqmm 13.2.1.3 Data Analysis 13.2.1.3.1 Signal topology 13.2.1.3.2 Main backgrounds already done in CMSJET and in FAMOS 13.2.1.3.3 Signal selection: qq -> qqVV -> qqVW -> qqqqmn we are moving to ORCA qq -> qqVV -> qqVZ -> qqqqmm 13.2.1.4 Results CPTweek / PRSsession 10/31/05 Sara Bolognesi (TORINO)

  3. 13.2 Heavy Higgs boson and VV scattering • In absence of the Higgs particle unitarity violation at 1-1.5 TeV -> new physics must be revealed • If the Higgs boson exists • nature of VLVL coupling is an indication of the Higgs mass range (useful for a light Higgs) • heavy Higgs = resonance in the M(VV) spectrum in any case we need to verify the unitarity of the VV fusion process at high M(VV) through a comparison of the measured s(VV->VV) with the SM predictions precise knowledge of the signal xsec is essential: any deviation from the expected xsec = new physics CPTweek / PRSsession 10/31/05 Sara Bolognesi (TORINO)

  4. q tag n / m p W / Z m V q p q q V V q tag q’ 13.2.1.1 Semilept. final state qq -> qqVV -> qqVW -> qqqqmn Our signal channels are qq -> qqVV -> qqVZ -> qqqqmm • clear experimental signature thanks to the isolated high pT muons s(VV->VW) * BR(V->jj) * BR(W->mn) ~ 170 fb • quite high BR s(VV ->VZ) * BR(V->jj) * BR(Z->mm) ~ 25 fb Hopefully we will have also the qq -> qqVV -> qqVW -> qqqqenchannel with PHASE + FAMOS CPTweek / PRSsession 10/31/05 Sara Bolognesi (TORINO)

  5. 13.2.1.2 Signal definition and simulation • bosons off mass shellness • spin correlations in the bosons decay For a correct s(VV) calculation • interference with all irred. backgr. • Gauge invariance six-fermions approach EVBA approximation generation of signal together with all the irreducible backgrounds so you need a “signal definition” to isolate the signal from this background at partonic level and “a posteriori” CPTweek / PRSsession 10/31/05 Sara Bolognesi (TORINO)

  6. 13.2.1.2.1 Six fermion final state processes • qq->qqqqmn simulated with PHASE at O(a6EW) 2 bosons produced without undergoing scattering single top and ttbar EW production “non resonant” diagrams • no EW top contribution • no “non resonant” diagrams Higgsstralhung, TGC, QGC -> 3 bosons outgoing • qq->qqVZ->qqqqmm simulated with MadEvent in the “production times decay” approximation = only on shell bosons (with zero width) a study on this approximation validity is on-going (comparison between MadEvent and PHASE) CPTweek / PRSsession 10/31/05 Sara Bolognesi (TORINO)

  7. 13.2.1.2.2 VV fusion signal selection To separate the signal from the irreducible background at partonic level • qq -> qqqqmn 100% • reject EW top contribution 28 % • request for two on-shell bosons 25 % • reject events with three on-shell bosons in the final state 23 % perc. of signal in simulated events • qq -> qqVZ -> qqqqmm ... we are working on the signal definition at partonic level ... CPTweek / PRSsession 10/31/05 Sara Bolognesi (TORINO)

  8. 13.2.1.3 Data Analysis A model indipendent analysis • no assumption on the mechanism to restore unitarity • no Higgs • no degrees of freedom beyond the SM A “CONSERVATIVE” APPROACH • M(H) = 500 GeV same analysis cuts valid for any mass (but optimized in the no Higgs case) CPTweek / PRSsession 10/31/05 Sara Bolognesi (TORINO)

  9. 13.2.1.3.1 Signal topology Dh h tag quarks quarks from boson decay pT E

  10. pp -> tt -> 1m + X 13.2.1.3.2 Main backgrounds process xsec (pb) generator submitted ev. we can use one of the producted samples 622 pp -> jjWW -> jjqqmn 9 250k pp -> jjZW -> jjqqmn 3 × 10-3 0 MadEvent pp -> jjZZ -> jjqqmm 0.35 250k pp -> jjWZ -> jjqqmm 0.9 × 10-3 50k pp -> W + n jets -> mn + n jets ~ (100 -1000) AlpGen ? pp -> Z + n jets -> mm + n jets (noHiggs / mh500) sign + irr. backgr. pp -> qqqqmn ~ 0.7 PHASE 250k / 125k sign+irr.backgr. pp -> qqVZ -> qqqqmm ~ 0.025 MadEvent 550k / 325k not yet generated j = q / g (producted via QCD) submitted to the production (q always producted via EW) already producted (Digi + SimHits) CPTweek / PRSsession 10/31/05 Sara Bolognesi (TORINO)

  11. 13.2.1.3.3 Signal selection A preliminar set of cuts has been already studied and optimized with CMSJETand FAMOS pTm > 20 GeV (inclusive muon) L1 trigger: |h|<2.4, pTm > 5 GeV (di-muons) signal final state reconstruction • ask for central, isolated and quite high pT muons and high MET (> 20 GeV) • ask for at least 4 jets with pT>30 GeV • choose the right quarks from the boson decay (high pT, central, near one to the other) background rejection • cut against top events (b-tagging) first indication from W+4jets: • requests on jet tag kinematic (very high h, Dh and energy) W/Z+n jets will be the most problematic background • cut against jets occupancy (signal = pure EW process) • request for high pTV and high M(qqVV) !!! we are moving to ORCA !!! CPTweek / PRSsession 10/31/05 Sara Bolognesi (TORINO)

  12. 13.2.1.4 Results (1) 30 % • Signal reconstruction efficiency as a function of M(VV) CMSJET NO HIGGS CASE: • qqqqmmfinal state • qqqqmnfinal state 1 TeV CMSJET FAMOS 50 % 10 % 1 TeV 1 TeV CPTweek / PRSsession 10/31/05 Sara Bolognesi (TORINO)

  13. 13.2.1.4 Results (2) qqqqmm final state • M(VV)resolution and OSCAR_2_4_5 ORCA_7_6_1 M(V->jj) resolution for the two channels M(Z->mm) resolution M(W->mn) resolution !! VERY PRELIMINARY !! • Number of signal and background events VS reconstructed M(VV) • Significance (S/√B) VS reconstructed M(VV) CPTweek / PRSsession 10/31/05 Sara Bolognesi (TORINO)

  14. Some open issues • estimate of theoretical uncertainties on the signal cross section calculation • through a comparison of various signal samples of the qqqqmn final state with different MC input parameters • scale • PDF set (CTEQ5L) • top mass 175 GeV • through a comparison between MadEvent and Phase in the qqqqmm final state • how to calculate the backgrounds cross section from data not yet considered, probably not ready for the P-TDR CPTweek / PRSsession 10/31/05 Sara Bolognesi (TORINO)

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