1. 1 H->ZZ->llvv Maosen Zhou 15/04/2014

2. 2 The ZZ→llvv decay channel offers a substantial branching fraction in combination with a good separation from potential bkg owing to large PT of lepton pair and large missing transverse momentum earlier results excluded : 310< mH <470GeV(ATLAS),270<mH<440GeV(CMS) for this letter : sqrt(s)=7TeV,Lumi = 4.7/fb with uncertainty of 3.9%

3. 3 Data and simulation samples sig : H→WW→lvlv, H→ZZ→lvqq H→ZZ→llll, H→ZZ→ττvv event generator: POWHEG final-state radiation: PHOTOS TAUOLA: τ decays

4. 4 bkg simulation ALPGEN: W/Z MC@NLO: top pair,single-top and diboson(WW,WZ,and ZZ) PYTHIA: bb~, cc~ ----------------------------------------------------------- low pile-up data:2.3/fb high pile-up data: 2.4/fb

5. 5 Lepton identification and event selection electrons: PT> 20GeV, |η|< 2.47 muons: PT> 20GeV, |η|< 2.5 jets: PT> 25GeV, |η|< 2.5 To remove leptons associated with jets,the below not considered: ›the scalar sum of ID track momenta(not associated with the lepton) in a cone ΔR<0.2 around the lepton direction is greater than 10% of the PT of the lepton itself ›the lepton is within a ΔR=0.4 of the nearest jet ·missing transverse momenta is measured as the negative vectorial sum of the transverse momenta of all cells in the calorimeter with |η|< 4.9

6. 6 event selection requirments:a primary vertex, at least 3 associated tracks with PT> 0.4GeV, 2 oppositely-charged leptons, | mZ-mll |< 15GeV ·,Δφ(l,l) ·To exploit the mass-dependent kinematic features,the search is subdivied into a low mass region(mH =280GeV) ›low region: >66GeV,1<Δφ(l,l)<2.64 ›high region: >82GeV,Δφ(l,l)<2.25

7. 7 Rejected events a third lepton events with one or more b-tagged jets in the high region: Δφ(, )<1 the azimuthal angle between and the nearest jet : Δφ(, )<1.5 for low mH and Δφ(, )<0.5 for high mH region ----------------------------------------------------------- The effciency of the event selection is very similar in the electron and muon channels,ranging from 3.1% for mH=200GeV to about 43% for mH=600GeV

8. 8 Bkg normalisation and control regions norma for SM pair-pro of Z bkg is obtained from calculation including NLO terms with an additional 6% term to account for missing quark-box diagrams and 11% norma uncer is assigned. top-quark bkg is taken from MC prediction,agreeing with data in two control regions: ›useing dilepton sideband and requiring >=1 b-jet ›events containing oppositely-charged e-u pairs ·norma for inclusive W pro is from control region with a like- sign e-u or e-e pair in the sidebands of dilepton mass distribution and with no b-tag jets. bkg from inclusive Z pro is taken from MC prediction. don't understand this section....

9. 9 Systematic uncertainties norma uncer for sig(gluon fusion +14%/-10% and VBF 4%) and for diboson bkg(11%) are from theory; inclusive Z boson pro(2.5%),top quark pro(9%),inclusive W boson pro(100%) and for multijet pro(50%) are estimated from data for sig, an additional uncer is applied to account for the possible effect of theoretical uncer on the acceptance ›low mass region: 8.4% ›high mass region: 3.4% ·Lumi uncer is 3.7% and 4.1% for low and high pile-up data,respectively

10. 10 Results:No indication of an excess is seen...

11. 11 ---------------------------------------------------------------- 319<mH<558GeV is excluded at the 95% CL