Search for the Higgs boson in the t th production mode using the ATLAS detector

Search for the Higgs boson in the t th production mode using the ATLAS detector Rustem Ospanov (University of Pennsylvania) on behalf of the ATLAS collaboration Large Hadron Collider Physics Conference, June 2nd, 2014 1 / 18

Introduction Higgs boson with m 125 GeV discovered via γγ, ZZ, WW decays Higgs boson Yukawa couplings probe flavor structure of the SM Higgs Yukawa couplings accessible at LHC: τ, µ, b and top quark Strong evidence for H ττ: 4.1σ for ATLAS and 3.2σ for CMS Figure by Hitoshi Murayama Evidently the Higgs system knows something that we do not know: the difference between the generations - Martinus Veltman. 2 / 18

Higgs-top quark coupling t th coupling Drives SM properties at high energy scale Indirect measurement via gluon fusion production Direct measurement via t th production t th production: σ(t th) 130 fb for m H = 125 GeV at s = 8 TeV 2600 events with 20.3 fb 1 Main background is t t + jets with σ 250 pb Decay modes: B(H b b) = 8 - dominant mode B(H γγ) = 2.3 3 - clean resonance signature B(H WW, ZZ, ττ) 0.3 - multi-lepton final states 3 / 18

t th t t + b b analysis strategy Tag tt decay by 1-lepton and 2-lepton Categorize by number jets and b-jets Increase sensitivity with different S/B Constrain systematic uncertainty by fitting regions with low S/B t th 6 jets 4 b-jets 1-lepton: t th 6 jets 4 b-jets 1 electron or muon 4 jets 2 b-jets 2-lepton: t th 4 jets 4 b-jets 2 electron or muon 2 jets 2 b-jets t th signal > 90% 4 / 18

t th t t + b b analysis strategy Tag tt decay by 1-lepton and 2-lepton Categorize by number jets and b-jets Increase sensitivity with different S/B Constrain systematic uncertainty by fitting regions with low S/B 1-lepton: t th 6 jets 4 b-jets 1 electron or muon 4 jets 2-lepton: 2 b-jets t th 4 jets 4 b-jets 2 electron or muon 2 jets 2 b-jets 1-lepton ATLAS Preliminary Simulation s L dt = 20.3 fb m H = 125 GeV B S / B S / B S / = 8 TeV, 1.0 4 j, 2 b S/B < 0.1% 0.0 1.0 5 j, 2 b S/B = 0.1% 0.0 1.0 0.0 6 j, 2 b S/B = 0.2% B S / B S / B S / 1.0 4 j, 3 b S/B = 0.2% 0.0 1.0 5 j, 3 b S/B = 0.4% 0.0 1.0 0.0 6 j, 3 b S/B = 0.9% S/ B for control regions S/ B for signal regions B S / B S / B S / Single lepton 1.0 0.0 1.0 0.0 1.0 0.0 4 j, 4 b S/B = 1.3% 5 j, 4 b S/B = 2.3% 6 j, 4 b S/B = 3.8% 5 / 18

t th t t + b b analysis strategy Tag tt decay by 1-lepton and 2-lepton Categorize by number jets and b-jets Increase sensitivity with different S/B Constrain systematic uncertainty by fitting regions with low S/B 1-lepton: t th 6 jets 4 b-jets 1 electron or muon 4 jets 2-lepton: 2 b-jets t th 4 jets 4 b-jets 2 electron or muon 2 jets 2 b-jets 2-lepton ATLAS Preliminary Simulation s L dt = 20.3 fb m H = 125 GeV B S / B S / B S / = 8 TeV, 0.6 2 j, 2 b S/B < 0.1% 0.4 0.2 0.0 0.6 3 j, 2 b S/B = 0.1% 0.4 0.2 0.0 0.6 4 j, 2 b S/B = 0.3% 0.4 0.2 0.0 B S / B S / 0.6 3 j, 3 b S/B = 0.7% 0.4 0.2 0.0 0.6 4 j, 3 b S/B = 1.8% 0.4 0.2 0.0 S/ B for control regions S/ B for signal regions B S / 0.2 0.0 Dilepton 0.6 4 j, 4 b S/B = 6.8% 0.4 6 / 18

t th t t + b b: backgrounds t t + jets Dominant background +5% 6% uncertainty Modeled with Powheg+Pythia Difference between Powheg and Madgraph is taken as uncertainty and pt t are re-weighted to unfolded 7 TeV data p tt T tt + b b same final state as signal Other backgrounds: t tw /Z - Madgraph+Pythia W/Z+jets - Alpgen+Pythia Diboson - Alpgen+Herwig QCD multi-jet - data-driven 1-lepton background composition 4 j, 2 b 4 j, 3 b 4 j, 4 b ATLAS Preliminary Simulation = 125 GeV m H s = 8 TeV 5 j, 2 b 5 j, 3 b tt+light 5 j, 4 b tt+cc tt+bb tt+v W+jets Z+jets Diboson Single top Multijet 6 j, 2 b 6 j, 3 b 6 j, 4 b Single lepton 7 / 18

t th t t + b b: backgrounds t t + jets Dominant background +5% 6% uncertainty Modeled with Powheg+Pythia Difference between Powheg and Madgraph is taken as uncertainty and pt t are re-weighted to unfolded 7 TeV data p tt T tt + b b same final state as signal Other backgrounds: t tw /Z - Madgraph+Pythia W/Z+jets - Alpgen+Pythia Diboson - Alpgen+Herwig QCD multi-jet - data-driven 1-lepton yields - post-fit 5 jets, 6 jets, 6 jets, 4 b-tags 3 b-tags 4 b-tags t th (125) 11 ± 1 ± 9 69 ± 3 ± 57 28 ± 2 ± 23 t t+ light 78 ± 9 2380 ± 130 78 ± 11 t t + c c 45 ± 12 750 ± 190 75 ± 19 t t + b b 149 ± 20 1160 ± 170 300 ± 40 t t + V 3.3 ± 1.0 44 ± 13 8.9 ± 2.7 non-t t 23.2 ± 2.5 218 ± 23 18.8 ± 2.2 Total 309 ± 11 4620 ± 80 507 ± 27 Data 283 4671 516 8 / 18

t th t t + b b: multi-variate discriminant inputs Event shape variables: event centrality,... Object pair properties: m min R b b,... Object kinematics: p jet5 T,... Event kinematics: HT had, N pt >40 GeV,... Modeling of variables and correlations checked in signal depleted regions 1-lepton centrality= p T / E 2-lepton m min R b b Arbitrary units s = 8 TeV 0.25 Total background Single lepton 6 j, 4 b tth (m = 125 GeV) H 0.2 ATLAS Preliminary Simulation Arbitrary units 0.6 ATLAS Preliminary Simulation s Dilepton = 8 TeV 4 j, 4 b Total background tth (m H = 125 GeV) 0.4 0.15 0.3 0.1 0.2 0.05 0.1 0 0.2 0.3 0.4 0.6 0.7 0.8 0.9 1 0 50 0 150 200 250 300 350 Centrality m bb 9 / 18

t th t t + b b: multi-variate discriminant output Neural Network trained in each signal region Select highest rank variables with NeuroBayes Use all MC events - weight light jets with b-jet mistag rate maps 1-lepton t th 6 jets 4 b-jets 2-lepton t th 4 jets 4 b-jets Events / 0.1 0 80 60 ATLAS Preliminary L dt = 20.3 fb, s = 8 TeV Single lepton 6 j, 4 b Data tth (125) norm tth (125) tt+light tt+cc t t+bb tt+v non-tt Total unc. Events / 0.2 25 20 15 ATLAS Preliminary L dt = 20.3 fb, s = 8 TeV Dilepton 4 j, 4 b Data tth (125) norm tth (125) tt+light tt+cc t t+bb tt+v non-tt Total unc. 40 20 5 Data / Pred 1.50 0 1.25 1 0.75-0.8-0.6-0.4-0.2 0 0.2 0.4 0.6 NN output Data / Pred 1.50 0 1.25 1 0.75-0.8-0.6-0.4-0.2 0 0.2 0.4 0.6 0.8 NN output / 18

t t + jets control regions 1-lepton 4 jet 4 b 2-lepton 4 jet 2 b Events / 50 GeV 60 50 40 ATLAS Preliminary L dt = 20.3 fb, s = 8 TeV Single lepton 4 j, 4 b Data tth (125) tt+light tt+cc tt+bb tt+v non-tt Total unc. Events / 30 GeV 900 800 700 600 500 ATLAS Preliminary L dt = 20.3 fb, s = 8 TeV Dilepton 4 j, 2 b Data tth (125) tt+light tt+cc tt+bb tt+v non-tt Total unc. 30 400 20 300 200 0 Data / Pred 1.50 0 1.25 1 0.75 0 200 400 600 800 00 1200 [GeV] H had T = p jet T had H T Data / Pred 1.50 0 1.25 1 0.75 200 400 600 800 00 1200 H T [GeV] H T = p jet T + p lepton T tt + b b and tt + c c are constrained from fits to signal depleted regions 11 / 18

Signal and control region yields 1-lepton yields post-fit 2-lepton yields post-fit Events / bin 6 5 ATLAS Preliminary L dt = 20.3 fb, s = 8 TeV Single lepton Data tth (125) t th (125) tt+cc tt+light tt+bb non-t t tt+v Total unc. Events / bin 5 4 ATLAS Preliminary L dt = 20.3 fb, s = 8 TeV Dilepton Data tth (125) t th (125) tt+cc tt+light tt+bb non-t t tt+v Total unc. 4 3 3 2 2 Data / Pred 1.5 1.25 1 0.75 4 j, 2 b 5 j, 2 b 6 j, 2 b 4 j, 3 b 5 j, 3 b 6 j, 3 b 4 b 4 j, 4 b 6 j, 5 j, 4 b Data / Pred 1.5 1.25 1 0.75 2 j, 2 b 3 j, 2 b 4 j, 2 b 3 j, 3 b 4 j, 3 b 4 j, 4 b Simultaneous binned likelihood fit to 6 signal and 9 control regions Measure t th signal strength µ and background normalization µ = 1 corresponds to SM t th prediction 12 / 18

t th t t + b b: systematic uncertainties - 0 1 µ Main systematic uncertainties tt+heavy flavor normalization Jet flavor tagging tt re-weighting to data and Madgraph tt theoretical uncertainties Reduced by fitting data tt+bb tt+cc tt normalisation tt+hf tt tt LightTag1 p T MCgen RW normalisation tt+hf MG-PP LightTag2 cross section tt+hf top p T RW RW CTag1 BTag3 t t + light t t + c c t t + b b Total pre-fit ±30 ±57 ±56 Total post-fit ±14 ±25 ±14 CTag2 JES1 tt+v cross section BTag2 BTag1 ATLAS Preliminary =125 GeV m H Pull Post-fit Impact on µ -2.5-0 1 1.5 2 (θ - θ 0 )/ θ 13 / 18

t th t t + b b: results ATLAS Preliminary s=8 TeV, L dt=20.3 fb ATLAS Preliminary s=8 TeV, L dt=20.3 fb Dilepton tot. stat. ( tot ) ( stat ) Dilepton 2.9 ± 2.3 ( 1.4 ) Lepton+jets Expected ± 1σ Expected ± 2σ Lepton+jets 1.3 ± 1.6 ( 0.8 ) Combination Observed Expected ( µ=1) Combination 1.7 ± 1.4 ( 0.7 ) 0 2 4 6 8 12 95% CL limit on σ/σ SM at m H =125 GeV 0 2 4 6 8 best fit µ=σ/σ SM for m H =125 GeV Observed (expected ) 95% CL limit 4.1 SM (2.6 SM) for m H = 125 GeV Best fit µ = 1.7 ± 1.4 ATLAS-CONF-2014-011 14 / 18

t th t t + γγ candidate event 15 / 18

t th t t + γγ: signal regions Hadronic tt channel: 6 jet 2 b - N signal = 0.36 Leptonic tt channel: 1-lepton, 1 b - N signal = 5 2 isolated high p T photons - search for m γγ resonance Model m γγ for background with exponential function Simultaneous fit to signal and control regions with relaxed kinematic cuts Events / 5 GeV 7 6 5 4 3 2 1 Leptonic Data ATLAS preliminary SR+CR background fit SM signal (m = 126.8 GeV) H SR-only background fit Signal region Leptonic channel 2000 Control region s = 8 TeV Ldt = 20.3 fb 00 0 1 120 130 140 150 160 m γγ [GeV] Events / 5 GeV 9 8 7 6 5 4 3 2 1 Hadronic Data ATLAS preliminary SR+CR background fit SM signal (m = 126.8 GeV) H SR-only background fit Signal region Hadronic channel 40 Control region s = 8 TeV Ldt = 20.3 fb 20 0 1 120 130 140 150 160 m γγ [GeV] 16 / 18

t th t t + γγ: results tth /σ SM 95% CL limit on σ tth 40 35 30 25 20 15 Observed CL s limit Expected CL s limit ± 1σ H γγ tth channels comb. ATLAS preliminary ± 2σ Data 2012 s = 8 TeV Ldt = 20.3 fb 5 0 120 122 124 126 128 130 [GeV] m H Observed 95% CL limit: 5.3 SM (6.4 SM) for m H = 126.8 GeV 92% uncertainty on σ(t th) and 5% uncertainty on BR(H γγ) 4-6% uncertainty on photon id and isolation in multi-jet environment 5-% uncertainty on jet energy scale and b-tagging in hadronic channel ATLAS-CONF-2013-080 17 / 18

Summary and outlook t th t t + b b Observed (expected) 95% CL limit: 4.1 SM (2.6 SM) t th t t + γγ Outlook Observed (expected) 95% CL limit: 5.3 SM (6.4 SM) Publications of improved analyses of these final states are forthcoming Results of multi-lepton analyses will be also published t th cross-section increases by 3.9 at s = 13 TeV compared to 8 TeV ATLAS pixel detector upgrade: added Insertable B-Layer Expect to reach SM sensitivity in Run 2 18 / 18

BACKUP 18 / 18

t th t t + b b analysis strategy 1-lepton: t th 6 jets 4 b-jets 1 electron or muon with p T > 25 GeV 4 jets 2 b-jets 2-lepton: t th 4 jets 4 b-jets 2 electron or muon with p T > 25(15) GeV 2 jets 2 b-jets eµ: H T > 130 GeV ll: m ll > 15GeV and Z veto Exactly 2 b ll: m ll > 60 GeV Jets with p T > 25 GeV in η < 2.5 70% b-tagging working point with 1% mis-tag 18 / 18

t th t t + b b: multi-variate discriminant output Neural Network trained in each signal region Select highest rank variables with NeuroBayes Use all MC events - weight light jets with b-jet mistag rate maps 1-lepton 5 jet 4 b 1-lepton 6 jet 3 b 1-lepton 6 jet 4 b Events / 0.1 70 60 50 40 ATLAS Preliminary L dt = 20.3 fb, s = 8 TeV Single lepton 5 j, 4 b Data tth (125) norm tth (125) tt+light tt+cc t t+bb tt+v non-tt Total unc. Events / 0.05 500 ATLAS Preliminary Data L dt = 20.3 fb, s = 8 TeV tth (125) norm tth (125) Single lepton tt+light 400 6 j, 3 b tt+cc t t+bb tt+v non-tt Total unc. 300 Events / 0.1 0 80 60 ATLAS Preliminary L dt = 20.3 fb, s = 8 TeV Single lepton 6 j, 4 b Data tth (125) norm tth (125) tt+light tt+cc t t+bb tt+v non-tt Total unc. 30 200 40 20 0 20 Data / Pred 1.50 0 1.25 1 0.75-0.8-0.6-0.4-0.2 0 0.2 0.4 0.6 NN output Data / Pred 1.50 0 1.25 1 0.75-0.8-0.6-0.4-0.2 0 0.2 0.4 0.6 NN output Data / Pred 1.50 0 1.25 1 0.75-0.8-0.6-0.4-0.2 0 0.2 0.4 0.6-0.8-0.6-0.4-0.2 0 0.2 0.4 0.6 NN output 18 / 18

t th t t + b b: multi-variate discriminant output Neural Network trained in each signal region Select highest rank variables with NeuroBayes Use all MC events - weight light jets with b-jet mistag rate maps 1-lepton 5 jet 4 b 1-lepton 6 jet 3 b 1-lepton 6 jet 4 b Events / 0.1 0 80 60 ATLAS Preliminary L dt = 20.3 fb, s = 8 TeV Dilepton 3 j, 3 b Data tth (125) norm tth (125) tt+light tt+cc t t+bb tt+v non-tt Total unc. Events / 0.1 140 120 0 80 ATLAS Preliminary L dt = 20.3 fb, s = 8 TeV Dilepton 4 j, 3 b Data tth (125) norm tth (125) tt+light tt+cc t t+bb tt+v non-tt Total unc. Events / 0.2 25 20 15 ATLAS Preliminary L dt = 20.3 fb, s = 8 TeV Dilepton 4 j, 4 b Data tth (125) norm tth (125) tt+light tt+cc t t+bb tt+v non-tt Total unc. 40 60 40 20 20 5 Data / Pred 1.50 0 1.25 1 0.75-0.8-0.6-0.4-0.2 0 0.2 0.4 0.6 0.8 NN output Data / Pred 1.50 0 1.25 1 0.75-0.8-0.6-0.4-0.2 0 0.2 0.4 0.6 0.8 NN output Data / Pred 1.50 0-0.8-0.6-0.4-0.2 0 0.2 0.4 0.6 0.8 1.25 1 0.75-0.8-0.6-0.4-0.2 0 0.2 0.4 0.6 0.8 NN output 18 / 18

1-lepton variables Variable Centrality H1 Definition Sum of the p T divided by sum of the E for all jets and the lepton Second Fox-Wolfram moment computed using all jets and the lepton mbb Mass of the combination of two b-tagged jets with the smallest R N jet 40 Number of jets with p T 40GeV R avg bb Average R for all b-tagged jet pairs m max p T jj Mass of the combination of any two jets with the largest vector sum p T Aplanarity b jet 1.5λ 2, where λ 2 is the second eigenvalue of the momentum tensor built with only b-tagged jets HT had mjj Rlep bb mbj m max p T bj muu p jet5 T R max p T bb mbb max m pt,uu m jjj Ruu m max p T bb Scalar sum of jet p T Mass of the combination of any two jets with the smallest R R between the lepton and the combination of two b-tagged jets with the smallest R Mass of the combination of a b-tagged jet and any jet with the smallest R Mass of the combination of a b-tagged jet and any jet with the largest vector sum p T Mass of the combination of two untagged jets with the smallest R Fifth leading jet p T R between two b-tagged jets with the largest vector sum p T Mass of the combination of two b-tagged jets with the largest invariant mass Scalar sum of the p T s of the pair of untagged jets with the smallest R Mass of the jet triplet with the largest vector sum p T Minimum R between two untagged jets Mass of the combination of two b-tagged jets with the largest vector sum p T 18 / 18

Variable m b b H T p jet3 T p jet4 T Centrality Aplanarity jet H1 H4 Rhl max R Rhl 2-lepton variables Definition Mass of the two b-tagged jets from the Higgs candidate system Scalar sum of jet p T and lepton p T s Third leading jet p T Fourth leading jet p T Sum of the p T divided by sum of the E for all jets and both leptons 1.5λ 2, where λ 2 is the second eigenvalue of the momentum tensor built with all jets Second Fox-Wolfram moment computed using all jets and both leptons Fifth Fox-Wolfram moment computed using all jets and both leptons R between the Higgs candidate and the closest lepton R between the Higgs candidate and the furthest lepton N Higgs 30 Number of Higgs candidates within 30 GeV of the defined Higgs mass mjj closest Dijet mass between any two jets closest to the defined Higgs mass max η η jj Maximum η between any two jets in the event mjj min m Minimum dijet mass between any two jets m max p T jj Mass of the combination of any two jets with the largest vector sum p T mbb Mass of the combination of two b-tagged jets with the smallest R Rbj Minimum R between a b-tagged jet and any jet Rlj Minimum R between any lepton and jet R max p T bb R between two b-tagged jets with the largest vector sum p T Rbb max m R between two b-tagged jets with the largest invariant mass 18 / 18

Variable ( 6j, 4b) ( 6j, 3b) (5j, 4b) (5j, 3b) R avg bb 1 5 5 - mbb 2 9 3 1 Centrality 3 2 1 - H1 4 3 2 - p jet5 T 5 8 - - Aplanarity b jet 6-7 - muu 7 7-2 R max p T bb 8 - - - Rlep bb 9 - m max p T bj 6 - - N jet 40-1 4 - mbj - 4 - - m max p T jj - - 6 - HT had - - 8 - mjj - - 9 - mbb max m - - - 3 pt,uu - - - 4 m jjj - - - 5 Ruu - - - 6 m max p T bb - - - 7 Table: The lists and rankings of the variables considered in each of the regions in the single lepton channel where a NN is used. 18 / 18

Variable ( 4j, 4b) ( 4j, 3b) (3j, 3b) max η η jj 1 1 1 mbb 2 8 - m b b 3 - - Rhl 4 5 - N Higgs 30 5 2 5 R max p T bb 6 4 8 Aplanarity jet 7 7 - mjj min m 8 3 2 max R Rhl 9 - - mjj closest - H T - 6 3 Rbb max m - 9 - Rlj - - Centrality - - 7 m max p T jj - - 9 H4 - - 4 p jet3 T - - 6 Table: The lists and rankings of the variables considered in each of the regions in the dilepton channel where a NN is used. 18 / 18

t t + jets signal region composition regions tth, H bb 1-lepton 4 j, 2 b 4 j, 3 b 4 j, 4 b ATLAS Preliminary Simulation = 125 GeV m H s = 8 TeV 5 j, 2 b 5 j, 3 b 5 j, 4 b tth, H bbb tth, H WW tth, H ττ tth, H gg tth, H cc tth, H ZZ tth, H others 6 j, 2 b 6 j, 3 b 6 j, 4 b Single lepton 2-lepton 2 j, 2 b ATLAS Preliminary Simulation = 125 GeV m H s = 8 TeV 3 j, 2 b 3 j, 3 b tth, H bbb tth, H WW tth, H ττ tth, H gg tth, H cc tth, H ZZ tth, H others 4 j, 2 b 4 j, 3 b 4 j, 4 b Dilepton 18 / 18

( 6j, 4b) systematic uncertainties Pre-fit t th (125) t t + light t t + c c t t + b b Jet energy scale ±6.5 ±14 ± ±8.2 Jet efficiencies ±1.6 ±5.4 ±2.5 ±2.4 Jet energy resolution ±0.1 ±8.5 ±4.1 ±4.3 b-tagging efficiency ±9.0 ±5.8 ±5.1 ±9.2 c-tagging efficiency ±1.9 ±7.3 ±14 ±2.8 Light jet-tagging efficiency ±1.0 ±17 ±4.4 ±1.5 t t modelling: reweighting ±11 ±13 ±13 t t modelling: parton shower ±7.5 ±1.8 ± t t heavy-flavour: normalisation ±50 ±50 Total pre-fit ±12 ±30 ±57 ±56 Total post-fit ±7.2 ±14 ±25 ±14 18 / 18

5 t t + jets signal regions ATLAS Preliminary s=8 TeV, L dt=20.3 fb Dilepton Lepton+jets Combination Dilepton Lepton+jets Expected ± 1σ Expected ± 2σ Observed Expected ( µ=1) 0 2 4 6 8 12 ATLAS 95% CL limit on σ/σ SM at m H =125 GeV Preliminary tot. stat. s=8 TeV, L dt=20.3 fb ( tot ) ( stat ) 2.9 ± 2.3 ( 1.4 ) 1.3 ± 1.6 ( 0.8 ) Events / bin Data / Bkgd. 5 4 3 2 1.8 1.6 1.4 1.2 ATLAS s=8 TeV Preliminary L dt =20.3 fb Comb. Single lepton and Dilepton tth (µ =1.7) + Bkgd. fit tth (µ =4.1) + Bkgd. 95% excl. Data 2012 tth (µ =1.7) fit tth (µ =4.1) 95% excl. Bkgd 0.8 1 0.6-4 -3.5-3 -2.5-2.5 - log (S/B) Combination 1.7 ± 1.4 ( 0.7 ) 0 2 4 6 8 best fit µ=σ/σ SM for m H =125 GeV 18 / 18

t th t t + γγ: analysis strategy Hadronic tt channel: 6 jet 2 b - N signal = 0.36 Leptonic tt channel: 1-lepton, 1 b - N signal = 5 Aim for high efficiency to maximize signal yields 80% b-tagging working point with 4% light quark jet rejection 2 isolated high p T photons - 40 (30) GeV Jets with p T > 25 GeV in η < 2.5 Arbitrary units 0.4 ATLAS Preliminary Non-isolated, non-tight γ ID γγ + l + jets (at least 1b) 0.35 L dt = 20.3 fb γγ + 2-4 jets (at least 1b) s = 8 TeV 0.3 γγ + 2-4 jets (b veto) Leptonic Channel 0.25 Arbitrary units 0.4 ATLAS Preliminary Non-isolated, non-tight γ ID γγ + >=6j 0.35 L dt = 20.3 fb γγ + 5j (b veto) 0.3 s = 8 TeV γγ + 5j (1b) Hadronic Channel 0.25 0.2 0.2 0.15 0.15 0.1 0.1 0.05 0.05 0 0 1 120 130 140 150 160 m γγ [GeV] 0 0 1 120 130 140 150 160 m γγ [GeV] 18 / 18