g g s High Mass Higgs at the Tevatron Matthew Herndon, University of Wisconsin Madison Higgs Days 2012

The Higgs Boson SM postulates a mechanism of electroweak symmetry breaking via the Higgs mechanism Interaction with the Higgs field results in masses for the W and Z vector bosons, Possible mass terms for the fermions Also expect and observable quanta of the field: Higgs boson Directly testable hypothesis by searching for the Higgs boson A primary goal of the Tevatron and LHC Now directly testable by measuring Higgs properties!

The Higgs Boson Where to concentrate you search One answer: where your experiment excels Higgs decay to pairs of mass vector bosons with leptonic decays Where the data says to look(just before final analyses) SM LEP Direct search: mH > 114GeV SM (Tevatron) indirect constraint: mH < 152GeV LHC: 115.5 < mH < 129 LHC: Look around 125 GeV Some Hints that optimizing the analysis at low mass was called for.

Tevatron Performance Over 10 fb-1! Enough data to make an impact at low mass 9.7/fb used in analysis

Tevatron Higgs History After LP 2007 we had predicted expected preface enhancements and extrapolated to 10fb-1 Improvement factors based on studies in data Expectation: 3σ evidence for Higgs possible at 115GeV 125 was a harder mass. Needed to exceed the expectations

SM Higgs Production and Decay High mass: HWWll decay available (ZZ used - contribution small) Takes advantage of large ggH production cross section Alternative production mechanisms WHWWW, ZHZWW, VBF: qqHqq->WWjj Significant contribution in events with 1, 2 or more jets and same sign leptons, three leptons events. Helps at low mass

Analysis Technique Expanded acceptance Expanded lepton acceptance in areas with weak/no dedicated lepton Id Multiple analysis channels beyond HWW: HZZ, HWW (lepton + jets), VH (same sign, trilepton, extra jets) and VBF (extra jets) Analyze specific event topologies Isolate subsets of signal/background processes for optimal discrimination Optimize inputs to discriminants as a function of mass Use of jet kinematics to find vector bosons and identify VBF events Control regions Check modeling of primary backgrounds Measure background cross sections where possible: Z, WW, WZ, ttbar Apply advanced techniques Add only order 10-20% sensitivity to the analysis but needed in regions where the spin correlation is not enough such as at low mass

SM Higgs: HWW HWWll - signature: Two high pT leptons and MET The most powerful analysis channel Primary backgrounds: WW and top in di-lepton decay channel Excellent physics based discriminants H μ+ ν W- W+ e- Spin correlation: Charged leptons go in the same direction

CDF WW 2+ Jet Analysis Signals Analysis improvements 25% imrpvement VHVWWl+l- MET jj analysis, VHB HWW + forward jets, ggHWW jj Analysis improvements Implementation of MCs with good 2+ jets modeling for backgrounds Use of jets kinematics: Energy and rapidity Use of dijet variables mass, delta rapidity Optimization of variables as a function of mH 25% imrpvement

CDF HWW Search As sensitive as individual Hbb searches as low mass Combination of CDF H  WW searches UW contribution HWW Channels: Exp. Limit σ/σH per channel and combined Exp. Limit 125 Exp. Limit 165 ggH: 0 Jets 6.68 1.41 ggH, VH, VBF: 2+ Jets 7.83 1.89 ggH: 1 Jet 9.11 1.83 Low mll 11.1 2.86 SS 11.7 3.93 Trilepton 11.6 4.07 Combined 3.08 0.69 Like WH -> WWW like sign dilepton ttH -> ttbb As sensitive as individual Hbb searches as low mass most sensitive analysis for mH > 128GeV Observed limit 2.98

DØ HWWll Search ll – signature subdivided by jet topology & lepton charge Further subdivided by lepton flavor BDT for DY suppression Example: HWWeμ + MET High purity channel Exp limit 1.19@165 – most powerful single Tevatron channel

DØ H: ljj ljj(jj): lepton + jets signature HWWljj, VHljjjj, WHlnubb High and low mass analysis at once At high mass takes advantage of large Wjj branching ratio Classifies events by number and type of b tag BDT based discriminant

DØ HWW Search Combination of DØ H  WW searches HWW Channels: Exp. Limit σ/σH per channel and combined Exp. Limit 125 Exp. Limit 165 H: eμ 5.22 1.19 H: ee, μμ 6.89 6.76 1.59 1.64 gg->H Combined 3.59 0.81 VH: SS leptons 11.6 5.89 VH: tri leptons 11.1 6.64 H: l+jets ---- 4.56 Combined 0.72 Like WH -> WWW like sign dilepton ttH -> ttbb hWW combined sensitivity more powerful that any of the low mass H analysis Observed limit 4.56

Tevatron Higgs Combination Exclusion driven by HWW No interesting WW signal observed Obs. Exclusion 147-180 GeV

Conclusions LHC has observed a boson with mass ~125 GeV! What we have measured so far almost certainly means it plays a part in electroweak symmetry breaking. The Tevatron experiments have achieved sensitivity to the SM Higgs boson production cross section at high and low mass The sensitivity of the CDF and DØ high mass searches make them a primary element of the Tevatron search at mass around 125 GeV We exclude at 95% C.L. the production of a SM Higgs boson of 147-180 GeV The observed data in HWW is compatible with a SM Higgs boson but not constraining