Search for high-mass ZZ resonances Aidan Robson University of Glasgow for the CDF Collaboration EPS, 21 July 2011

Aidan RobsonSearch for high-mass ZZ resonances at CDF2 Z Z q q’ non-SM q q’ Z Z Z/  BSM? q q’ Z Z ? SM  Higgs?  RS graviton?  RS graviton in models with SM fields in bulk? eg Fitzpatrick, Kaplan, Randall, Wang, JHEP 0709 (2007) 013

Aidan RobsonSearch for high-mass ZZ resonances at CDF3 Z Z ? l+l+ l–l– l’ + l’ – Z Z ? l+l+ l–l– Z Z ? l+l+ l–l– jet 4l4l ll +E T ll jj

Aidan RobsonSearch for high-mass ZZ resonances at CDF4   = 1.0  = 0.6  = 2.0 muon chambers  =2  = m tracker had cal hadronic cal EM cal had cal solenoid pre-radiator shower max silicon EM cal  =1 CDF Include outer rings of calorimeters in electron ID retrack for 4 l, and add central tracker hits to forward silicon tracks Acceptance improvements for 4 l Improved shower max clustering → loosen cuts

WZ → lll +E T Aidan RobsonSearch for high-mass ZZ resonances at CDF5 q q’ W Z/  W σ(pp → WZ) = (4.1 ± 0.7) pb m T (W) ETET ETET  channel e channel

4l4l Aidan RobsonSearch for high-mass ZZ resonances at CDF6 Z Z ? l+l+ l–l– l’ + l’ –

ZZ → 4 l Aidan RobsonSearch for high-mass ZZ resonances at CDF7 Select 4 leptons (e or  ) p T (lepton)>15 GeV/c (one > 25 GeV/c) 10 candidates 76<m ll <106 GeV/c 2 ; 8 remain All same-flavour, opposite charge Expected background < 0.01 event σ(pp → ZZ) = (2.8 (stat) ± 0.3 (sys) ) pb +1.2 – 0.9 NLO prediction (1.4± 0.1) pb Cross-section assuming standard model source: CDF other analysis cross-sec, ZZ → 4 l + ZZ → ll ll dominates: σ(pp → ZZ) = (1.6±0.3(stat) (sys)) pb +0.3 – 0.2

ZZ → 4 l Aidan RobsonSearch for high-mass ZZ resonances at CDF8 High mass: eeee ee  

ZZ → 4 l Aidan RobsonSearch for high-mass ZZ resonances at CDF9 Most kinematic properties are as expected from SM prediction

ZZ → 4 l Aidan RobsonSearch for high-mass ZZ resonances at CDF10 For the high-mass events p T (ZZ) is not like SM prediction

ZZ → 4 l Aidan RobsonSearch for high-mass ZZ resonances at CDF11

ZZ → 4 l Aidan RobsonSearch for high-mass ZZ resonances at CDF12 p T (ZZ) M(ZZ) For mean expected events prob. to observe ≥4 events with M ZZ >300GeV/c 2 where M ZZ of at least 4 within any 20GeV/c 2 window: O(10 –4 ) (a range, depends Additionally include p T (ZZ) in likelihood: O(10 –5 ) Prob. of likelihood of p T (ZZ) distribution alone being less than that of the data for high-mass events: O(10 –4 )

ll +E T Aidan RobsonSearch for high-mass ZZ resonances at CDF13 Z Z ? l+l+ l–l– Expected yield: 10 x ZZ → 4 l

ll +E T Aidan RobsonSearch for high-mass ZZ resonances at CDF14 Select Z → ee & Z →  as for llll channel Signal region defined as E T >100GeV Here normalising Z+jets using: 50<E T <100 GeV and |  min |<0.5 Here cross-checking W+jets jet → lepton misidentification method using same-charge events with 50<E T <100 GeV angle between E T and closest jet (or lepton) same-charge

ll +E T Aidan RobsonSearch for high-mass ZZ resonances at CDF15

ll +E T Aidan RobsonSearch for high-mass ZZ resonances at CDF16 M vis = | (E,p) lep 1 + (E,p) lep 2 + (|E T |,E x,E y,0) | electron channel muon channel standard model13.6± ±1.8 data189 expected M(G*)=325GeV/c 2, 1pb signal 17±1 18±1 RS graviton, M(G*)=325 GeV/c 2, recoiling against a parton with E T >100GeV

ll jj Aidan RobsonSearch for high-mass ZZ resonances at CDF17 Z Z ? l+l+ l–l– jet Expected yield: 20 x ZZ → 4 l

ll jj Aidan RobsonSearch for high-mass ZZ resonances at CDF18 Select Z → ee & Z →  as for llll channel Additionally, ≥2 jets E T >25GeV 70<M jj <110 accepted as a Z candidate electron channel muon channel Here, M(lljj)<300GeV/c 2 defines control region for Alpgen Z+jets normalisation

ll jj Aidan RobsonSearch for high-mass ZZ resonances at CDF19 electron channel muon channel standard model424±40266±24 data expected M(G*)=325GeV/c 2, 1pb signal 41±1 32±1 E T (leading jet)>50GeV

ll jj Aidan RobsonSearch for high-mass ZZ resonances at CDF20 E T (leading jet)>50GeV and p T (ll) or p T (jj) > 40GeV/c

Aidan RobsonSearch for high-mass ZZ resonances at CDF21 ll jj ll +E T M(G*)=325GeV/c 2 expected observed expected observed RS: 0.29 pb 0.25 pb0.38 pb 0.23 pb Boosted RS: 0.30 pb 0.30 pb0.27 pb 0.26 pb

Aidan RobsonSearch for high-mass ZZ resonances at CDF22 llll + ll +E T + ll jj llll M(G*)=325GeV/c 2 expected observed expected observed RS: 0.7 pb 1.9 pb0.19 pb 0.26 pb Boosted RS: 0.17 pb 0.28 pb

Aidan RobsonSearch for high-mass ZZ resonances at CDF23 Searched for heavy resonances decaying to Z pairs  M ZZ and p T (ZZ) distributions in 4 lepton channel are different from those expected from standard model  Four events have M ZZ consistent with 327GeV/c 2  ll +E T and ll jj channels do not confirm a new resonance  limits set at level of 0.3pb in RS graviton models

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Aidan RobsonSearch for high-mass ZZ resonances at CDF29 RS1 graviton, k/M P =0.1 M=600 GeV/c 2,  (pp → G → ZZ) ≈ 1pb M=700 GeV/c 2,  (pp → G → ZZ) ≈ 0.1pb Previous CDF limit 491 GeV/c 2.

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