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

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

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

4 p p q q   q’ q W / Z V V V q tag Semilept. final state qq -> qqVV -> qqVW -> qqqq  qq -> qqVV -> qqVZ -> qqqq   clear experimental signature thanks to the isolated high p T muons  quite high BR Our signal channels are CPTweek / PRSsession 10/31/05 Sara Bolognesi (TORINO)  (VV->VW) * BR(V->jj) * BR(W->  ) ~ 170 fb  (VV ->VZ) * BR(V->jj) * BR(Z->  ) ~ 25 fb Hopefully we will have also the qq -> qqVV -> qqVW -> qqqqe channel with PHASE + FAMOS

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

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

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

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

Signal topology  pTpT E tag quarks quarks from boson decay

Main backgrounds CPTweek / PRSsession 10/31/05 Sara Bolognesi (TORINO) xsec (pb)generatorsubmitted ev.process pp -> jjWW -> jjqq  pp -> jjZW -> jjqq  pp -> jjZZ -> jjqq  pp -> jjWZ -> jjqq  pp -> W + n jets ->  + n jets pp -> Z + n jets ->  + n jets sign + irr. backgr. pp -> qqqq  sign+irr.backgr. pp -> qqVZ -> qqqq  MadEvent AlpGen PHASE MadEvent ~ ( ) ? submitted to the production not yet generated already producted (Digi + SimHits) j = q / g (q always producted via EW) (producted via QCD) pp -> tt -> 1  + X 250k 9 3 × k × k 250k / 125k~ 0.7 ~ k / 325k we can use one of the producted samples (noHiggs / mh500) 622

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

12  Signal reconstruction efficiency as a function of M(VV) CPTweek / PRSsession 10/31/05 Sara Bolognesi (TORINO) Results (1) 10 % 50 % 30 % 1 TeV  qqqq  final state  qqqq  final state NO HIGGS CASE: CMSJET FAMOS

Results (2)  M(VV) resolution and M(V->jj) resolution for the two channels M(Z->  ) resolution M(W->  ) resolution  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) qqqq  final state OSCAR_2_4_5 !! VERY PRELIMINARY !! ORCA_7_6_1

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