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Conf results quick summary: Cross section precision 10…15% (largely ∼

systematic): ATLAS and CMS 1σ above NLO ∼prediction

aTGC limits sensitive to high leading lepton pT : limits in between Tevatron and LEP

SM WW->lνlν 4.7fb-1 analysis: Moriond results• Measurement of the WW production

cross-section in the di-lepton (e,μ) final state

• Motivation:• Important test of the electroweak

sector of the Standard Model• Irreduciable background for Higgs

searches.• Sensitive to anomalous triple gauge

couplings• Updated to 1.02 fb-1

• Latest 4.7 fb-1 results for Moriond EW 2012(support note, conf note, conf talk)• Update BOTH fiducial and inclusive

cross-sections for full 2011 dataset• Working on optimization and

including aTGC 4.7fb-1 updates.• 1fb-1 presented aTGC limits

presented in Moriond

qq->WW production σNLO = (43.8±2.25)pb at 7TeV

gg->WW contributes additional ~3% of WW event rate: 1.3pb

WW background estimation: Wjets and Top

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Wjet DD estimate: Jets misidentified as leptons not correctly

modeled and limited by stat. in MC W+jets enriched control sample and fake factor

measured in data W+jets CR: nominal cuts w/ looser lepton ID for

one of the 2 leptons Fake factor: ratio of and looser (“jet-rich”) leptons Cross-check of method in SS CR.

Top DD estimate using b-tagged control sample – P1: b-tagging control sample jet Veto survival

probability– P2: full jet veto survival probability

Agree w/ MC prediction. ~20.4% overall syst. Dominated by theo.

Uncertainty~15% and sample dependence~12%

Channel Top (MC) Top (DD)ee 15.8±1.0(stat.) 14.0±2.0(stat.)±2.9(syst.)

eμ 70.4±2.0(stat.) 70.8±5.2(stat.)±14.4(syst.)

μμ 20.0±1.1(stat.) 25.2±2.9(stat.)±5.1(syst.)

combined 106.3±2.5(stat.) 110.0±6.2(stat.)±22.4(syst.)

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WW background estimation: Drell-Yan and other DiBosonDY bgd: lepton or jet energy not well measuredThe Etmiss,Rel not well modeled in DY MC, use a data-driven scale factor to correct for the Etmiss,rel cut efficiency.Procedure:

Invert Z window veto, apply other nominal selection cuts ee, μμ: S Factor

eμ: no Z cut, use MC prediction w/ syst. estimate from ee/μμ using same Etmiss,Rel cut value in eμ, corresponding difference quoted.

Expected DiBoson Yields(purely MC prediction)

Wγ* partially double counted in WZ, thereforescaled down in each channel based on ratio passing WZ gauge boson high mass cut

Acceptance and Fiducial xsecFiducial cross section measured in the phase space mimic the nominal selection

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-0.3σ+1.4σ+1.5σ+1.4σ

Deviate from SM prediction

The total WW production x-section is determined from 3 dilepton channels (ee, μμ and eμ) by maximising log-likelihood functions:

Overall WW signal acceptance determined by MC

Overall WW signal acceptance determined by MC

On-going effort for 4.7fb-1 publication• Optimization I: track-based MET

– Track MET supposedly less sensitive to pileup– Missing neutral part, larger DY tail less good resolution– expected to be a powerful weapon against DY contamination for WW SR.– Tested different MVA tech. – Combined w/ more discriminants– To be considered for 2012 analysis due to the time scale of publication

• Optmization II: ptll and MC rescaling– Ptll cut combined with jet Veto will enhance the DY processes boosted by low Energy

activities which can not be expected to be well modeled in MC– M(ll) line-shape scale factor to correct for the MC prediction of DY. Work to be discussed

and finalized…

23/4/21 5ee+μμ combined

ee+μμ combined

Ptll cut eff rescale

Ptll cut eff rescale

Drell-Yan CR def:•Etmiss,rel [5,30]GeV favored•Passing full-jet veto and ptll•Subtract all ther other background and signal

Truth deviation

Truth deviation

MVA performance

MVA performance

Z-window distribu

tion

Z-window distribu

tion

Spare

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Final WW candidate plotsapproved for Moriond

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PT(l+l-) Δφ(l+l-)

MT(l+l-, Etmiss)

PT(l+l-, Etmiss)

leading pT subleading pT