Prospects of Prospects of combined measurements of combined - PowerPoint PPT Presentation

Prospects of 
 Prospects of 
 combined measurements of 
 combined measurements of Higgs boson properties Higgs boson properties Dag Gillberg 
 Carleton University 2016-08-31

Outline • Outline • LHC Schedule • Run-1 highlights of Higgs boson measurements • Run-2 first Higgs results • Projections of Higgs boson results • LHC and ATLAS detector upgrades • Mass • Couplings • Rare decays • Di-Higgs production Dag Gillberg (Carleton) 2

LHC Schedule 13.5 TeV? 2026-2037 30+120 = 150 • LHC operates very well: 
 current data acquisition exceeds expectation • Higher centre-of-mass energy means larger cross sections 
 ggF, VBF, VH : ~ ⨉ 2, ttH ⨉ 4 (similar for associated backgrounds) • Expect • 30 fb -1 @ 13 TeV by end of 2016 • 120 fb -1 @ 13-13.5 TeV by end or Run-2, 2018 • ~300 fb -1 @ 13-14 TeV by end of Run-3, 2023 • ~3000 fb -1 @ 14 TeV , HL-LHC, 2026-2037 Dag Gillberg (Carleton) 3

I. Run-1 highlights based on ~25 fb-1 7-8 TeV data

Run-1 Higgs boson highlights PRD 92 (2015) 012006 weights / GeV Events / 2.5 GeV 180 -1 ATLAS ∫ L dt = 4.5 fb , s = 7 TeV 35 ATLAS Data -1 L dt = 20.3 fb , s = 8 TeV ∫ Data 160 ATLAS H WW* → S/B weighted sum → → Signal (m = 125 GeV = 1.51) µ H ZZ* 4 l Events / 10 GeV H Signal+background Signal strength categories 140 800 30 -1 ∫ s =8 TeV, 20.3 fb Background ZZ* ∑ -1 Background s = 7 TeV Ldt = 4.5 fb -1 120 Signal Background Z+jets, t t ∫ s =7 TeV, 4.5 fb -1 s = 8 TeV Ldt = 20.3 fb m = 125.4 GeV 25 H Systematic uncertainty (a) n 1 , e + ee/ µ µ µ 100 ≤ 600 j H → ZZ* 
 Obs stat ± 80 20 Bkg syst ± H → γγ 
 8.1 σ (6.2 σ ) 60 400 Higgs 15 40 WW 5.0 σ (4.6 σ ) Misid 20 10 VV 200 0 Top weights - fitted bkg 10 DY 5 5 0 0 0 0 (b) Background-subtracted Events / 10 GeV -5 80 90 100 110 120 130 140 150 160 170 ∑ Obs - Bkg 150 110 120 130 140 150 160 PRD 91 (2015) 012006 Bkg syst ± PRD 90 (2014) 902015 m [GeV] m [GeV] 4 l Higgs γ γ Events / bin 4 Weighted events after subtraction / 20.0 GeV 10 100 Data 2012 ATLAS Data H → WW* 
 10 VH(bb) ( =1.0) µ ∫ -1 s = 8 TeV Ldt = 20.3 fb Diboson Background ( =1.4) µ Uncertainty 0+1+2 lep., 2+3 jets, 2 tags 6.8 σ (5.8 σ ) Background ( µ =0) Weighted by Higgs S/B 8 50 3 10 H (125) ( =1.4) → τ τ µ H → bb 
 H → ττ 
 H (125) ( =1) → τ τ µ 6 0 1.7 σ (2.7 σ ) 4.5 σ (3.4 σ ) 2 10 4 50 100 150 200 250 H → τ τ 10 m [GeV] T 2 σ ( H → Z γ ) < 11 × SM ATLAS -1 s = 8 TeV , 20.3 fb σ ( H → µµ ) < 7 × SM 0 1 -1 s = 7 TeV , 4.5 fb Observed (expected) sign. from 50 100 150 200 250 -4 -3 -2 -1 0 1 JHEP 01 (2015) 069 Dag Gillberg (Carleton) Bertrand Laforge, ICHEP 2016 5 JHEP 04 (2015) 117 JHEP 08 (2016) 045 m [GeV] log (S / B) bb 10

Run-1 Higgs boson results Spin/CP Higgs boson mass ATLAS H ZZ* 4 l → → -1 s = 7 TeV, 4.5 fb Observed -1 Expected s = 8 TeV, 20.3 fb ATLAS and CMS + 0 SM 1 ± σ Syst. Total Stat. H WW* e → → ν µ ν + LHC Run 1 0 SM 2 ± σ Total Stat. Syst. -1 s = 8 TeV, 20.3 fb + 0 SM 3 ± σ ATLAS H → γ γ 126.02 ± 0.51 ( ± 0.43 ± 0.27) GeV P J 1 ± σ H → γ γ P CMS H 124.70 0.34 ( 0.31 0.15) GeV → γ γ ± ± ± J 2 ± σ -1 s = 7 TeV, 4.5 fb ˜ P q J 3 ± σ -1 ATLAS H ZZ 4 l 124.51 0.52 ( 0.52 0.04) GeV → → ± ± ± s = 8 TeV, 20.3 fb ~ q 40 CMS H → ZZ → 4 l 125.59 ± 0.45 ( ± 0.42 ± 0.17) GeV 30 ATLAS + CMS 125.07 0.29 ( 0.25 0.14) GeV γ γ ± ± ± 20 ATLAS + CMS 4 l 125.15 0.40 ( 0.37 0.15) GeV ± ± ± 10 ATLAS + CMS +4 l 125.09 0.24 ( 0.21 0.11) GeV γ γ ± ± ± 0 123 124 125 126 127 128 129 -10 m [GeV] PRL 114 (2015) 191803 H -20 -30 P + P − P + P + P + P + P + J = 0 J = 0 J = 2 J = 2 J = 2 J = 2 J = 2 Precision of mass measurement: 0.2% 240 MeV • h = κ κ κ =0 κ =0 κ =2 κ κ =2 κ q g q q q g q g p <300 GeV p <125 GeV p <300 GeV p <125 GeV T T T T Statistically limited , especially for ZZ* → 4l : stat error ≈ 10 ⨉ syst error • Consistent with SM spin/CP expectation 0 + 
 • EPJC 75 (2015) 476 Alternative models (spin 2, negative parity, etc.) excluded at at least 99.9% CL Dag Gillberg (Carleton) 6

Run-1 Higgs boson results • The Higgs boson production and decay were studied using • Dedicated analyses in 7 different decay modes ( γγ , ZZ*, WW*, bb, ττ , Z γ , µµ) • Full Run-1 dataset: ~25 fb -1 • All results are consistent with the Standard Model expectation • “Micro-anomalies”: 
 H → bb low by ~2.5 σ , ttH high by ~2.3 σ 4 F κ ATLAS 3 -1 s = 7 TeV, 4.5-4.7 fb 7 VBF+VH -1 s = 8 TeV, 20.3 fb ATLAS Standard Model 2 m = 125.36 GeV 6 Best fit H -1 s = 7 TeV, 4.5-4.7 fb f µ 68% CL -1 s = 8 TeV, 20.3 fb 5 95% CL 1 H WW* → 4 H ZZ* → H bb 0 → 3 H → γ γ H → τ τ 2 1 − 1 H → γ γ 2 − H ZZ* → 0 H WW* → H → τ τ 3 1 − SM 68% CL − H bb → m = 125.36 GeV Combined H Best fit 95% CL 2 − 2 1 0 1 2 3 4 5 6 7 4 − − − 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 Dag Gillberg (Carleton) 7 EPJC (2016) 76:6 f µ κ ( a ) ggF+ttH V

Run-1 Higgs boson results • Differential cross sections and normalized shapes of kinematic distributions measured both in individual channels (fiducial regions of γγ , ZZ*, WW* ) and combined ( γγ +ZZ* ), correcting for acceptances and branching ratio • Higgs boson p T , jet multiplicity, m jj , etc. • “Micro-anomalies”: p T ,H spectrum harder and more jets (see below) 
 p -value for SM-agreement: 4% (8%) or better for norm+shape (shape-only) Phys. Rev. Lett. 115 (2015) 091801 [pb] [pb/GeV] N +P 8 + XH NLOPS Y ATLAS pp H → + XH HR ES +P 8 + XH MG5_aMC@NLO 1 Y data, tot. unc. syst. unc. 2 σ = VBF + + + XH VH t t H b b H 10 S + XH HERPA 2.1.1 syst. unc. data, tot. unc. -1 STWZ + XH s = 8 TeV, 20.3 fb BLPTW + XH jet -1 anti- k R = 0.4, p > 30 GeV s = 8 TeV, 20.3 fb H T t T XH = VBF + VH + t t H + b b H p / d ATLAS pp H → σ 10 1 − d 10 1 2 − 10 0 20 40 60 80 100 120 140 160 180 200 HRes NNLOPS 0 1 2 3 4 5 6 4 4 Ratio to 2 Ratio to 2 0 0 0 20 40 60 80 100 120 140 160 180 200 1 2 3 = 0 = 1 = 2 ≥ ≥ ≥ Dag Gillberg (Carleton) 8 H [GeV] N p jets T 40 | [pb]

II. Current Run-2 results H → ZZ → 4 l , 14.8 fb -1 H → γγ , 13.3 fb -1 See talk by Yusheng Wu for details on the individual analyses


 
 
 pp → H cross section ( γγ +4 l ) [pb] • Extracted event yields after ATLAS Preliminary σ m = 125.09 GeV 100 pp → H H analysis selection (without H QCD scale uncertainty H H ZZ * 4 → γ γ → → l → further categorization) are Tot. uncert. pp (scale PDF+ ) ⊕ α syst. unc. comb. data s converted to a production 
 σ 80 cross section: 
 60 1 σ pp → H = n data ε L × B SM A SM 40 BR and acc. 
 Fiducial cross Fiducial → total 
 section 20 extrapolation -1 s = 7 TeV, 4.5 fb -1 • Profile likelihood ratio fit with s = 8 TeV, 20.3 fb 0 -1 -1 systematics implemented as s = 13 TeV, 13.3 fb ( ), 14.8 fb ( ZZ *) γ γ ~200 nuisance parameters used 7 8 9 10 11 12 13 boson mass of 125.09 GeV [9]. s [TeV] Decay channel Total cross section ( pp → H + X ) √ s = 7 TeV √ s = 8 TeV √ s = 13 TeV 35 + 13 30 . 5 + 7 . 5 37 + 14 H → �� − 12 pb − 7 . 4 pb − 13 pb 33 + 21 37 + 9 81 + 18 H → ZZ ∗ → 4 ` − 16 pb − 8 pb − 16 pb 34 ± 10 (stat . ) + 4 33 . 3 + 5 . 5 − 5 . 3 (stat . ) + 1 . 7 59 . 0 + 9 . 7 − 9 . 2 (stat . ) + 4 . 4 Combination − 2 (syst . ) pb − 1 . 3 (syst . ) pb − 3 . 5 (syst . ) pb 55 . 5 + 2 . 4 SM predictions [7] Dag Gillberg (Carleton) 19 . 2 ± 0 . 9 pb 24 . 5 ± 1 . 1 pb − 3 . 4 pb 10

Run-2 Higgs boson couplings • Targeting Higgs production mode with dedicated analysis event categories: 13 for γγ , 5 for ZZ → 4 l . • Combined fits for cross sections and coupling parameters performed using these categories • Global signal strength: 
 ~10 σ (8.6 σ ) significance SM BR 
 • Fitted production mode cross sections (below and assumed right) consistent with SM expectation Dag Gillberg (Carleton) VBF vs ggF 11

III. Projected results • 120 fb -1 @ 13-13.5 TeV by end or Run-2, 2018 • ~300 fb -1 @ 13-14 TeV by end of Run-3, 2023 • ~3000 fb -1 @ 14 TeV , HL-LHC, 2026-2037 (Runs 4&5)