CMS Higgs Results Adi Bornheim Caltech

Transcription

1 CMS Higgs Results Adi Bornheim Caltech

2 A brief history of recent times W & Z Boson t-quark H Boson Peter Higgs This talk : Summary of 29 CMS publications and many preliminary results. Adi Bornheim, CMS Higgs Results, APS Meeting 2014, 2

3 The CMS Collaboration 3

4 The LHC Accelerator X TeV 0.8 X σ H discovery 20 MHz Average 400 MHz Pile up : 40 vertices, 14 jets, 2 TeV 4

5 Cross sections and branching ratios Five production processes, cross section varying by factor >200. Nine different decay modes, varying by almost four orders of magnitude. Any possible combinations of final state objects. 5

6 CMS SM Precision Measurements More than 300 CMS publications are evidence for a very good understanding of our detector, simulation and backgrounds Adi Bornheim, CMS Higgs Results, APS Meeting 2014, 6

7 The CMS Detector All Silicon Tracker, High resolution Crystal ECAL Brass-Scintillator HCAL 3.8 Tesla Magnet Drift Tube and Resitive Plate Chamber Muon System 7

8 8 HIG H WW

9 HIG H WW Very large branching ratio, but large backgrounds. Missing energy in final state poor mass resolution. Use RAZOR variables to optimize signal line shape. 9

10 HIG H WW Analysis in many event categories (ee, µµ, eµ, 0/1/2 jets) Significance : 4.3 σ at GeV, observed cross section µ= Signal yield from LHC Run 1 in clean categories (eµ 0/1 jet) order 100 events

11 HIG H WW - Mass Large variation of σ BR(H WW) with m H at fixed signal strength. Linear dependency of m R peak on m H with approximately constant resolution. m H = GeV -5.3 m H =125.5±3.8 GeV 11

12 HIG H WW - Coupling and Spin Spin-parity J P =0 + favored against narrow J P =2 + or J P =0 - Production cross section consistent with SM Coupling consistent with SM expectation. µ ggh κ f µ VBF,VH κ V 12

13 HIG H ZZ 4l Adi Bornheim, CMS Higgs Results, APS Meeting 2014, 13

14 14 HIG H ZZ 4l Mass Resolution H ZZ 4e At low Higgs masses steep drop of acceptance x efficiency. Analysis challenge : Low pt lepton acceptance and performance. σ E =2.0 GeV acceptance x efficiency H ZZ 4l Muon Mass Scale m < 0.1%

15 HIG H ZZ 4l signal Clean, narrow peak over a modest, well simulated background. Significance of 6.8 σ, µ = Invariant Mass Spectrum ZZ 4l < m 4l < ee, 13 µe, 8 µµ events 1

16 HIG H ZZ 4l - Mass and Spin Mass : ± 0.4 (stat) ± 0.2 (sys) Pseudo scalar and all spin 1 hypothesis excluded at >99%, spin 2 excluded at > 95% confidence level. Spin Hypothesis Tests 16

17 HIG H ZZ 4l - Production Mode Gluon fusion and VBF production rates as expected from SM. Dijet 0/1-jet best fit µ 17

18 HIG H ZZ 4l - Width from Interference Interference cause ZZ event rate change of ~8% for m 4l >2m Z for Γ H = Γ H SM Obs. 95% C.L. : Γ H < 4.2 (8.5) Γ H SM, Γ H < 17.4 (35.3) MeV Γ H /Γ SM m 4l (GeV) MELA Dgg H 18

19 H γγ Adi Bornheim, CMS Higgs Results, APS Meeting 2014,

20 HIG H γγ H γγ : Narrow peak - width determined by experimental resolution - over a large background. Expect >500 H γγ events in LHC run 1 data after final selection. Background in final analysis categories dominated by QCD di-photon production irreduceable. Analysis strategy : Improve S/B by categorizing events according to Higgs production mode, Higgs kinematics and photon reconstruction performance. H γγ Signal Model : σ m ~1% Calibration with > 3x10 9 π m γγ (GeV) 2 0

21 HIG H γγ Preliminary results from Moriond 2013 : Observed excess 3.2 σ, µ = m H : 125.4±0.5(stat)±0.6(stat) Final results for LHC run 1 expected for summer conferences : Improved ECAL calibration, improved detector simulation, refined categorization, optimized energy reconstruction and photon identification. Channel compatibility for two alternative analysis 21

22 HIG Properties measured in H γγ Preliminary results : Acceptance of current analysis drops in region of largest sensitivity. Particular spin-2 model tested cannot be ruled out. Observed data is compatible with the SM with a χ 2 p-value of cos(θθ* CS ) f qq (%) 22

23 HIG H γγ VBF Production m γγ in γγ +2 jets category µ VBF,VH Photon µ ggh, tth Photon Jet Jet Jet 23

24 HIG VH bb Mass Resolution H bb m(jj) (GeV) Muon 1, pt : 27.3 GeV Muon 0, pt : GeV 24

25 HIG VH bb Very large backgrounds from SM processes. Use associated production mode to enhance S/B. S/B from BDT, all channels combined Dijet mass cross-check 25

26 HIG VH bb Six topologies considered. Significance around 2 sigma at 125 GeV. WH and ZH production modes consistent with SM expectations 26

27 H ττ 27

28 H ττ 28

29 HIG H ττ Observed significance 3.2 σ at m H =125 GeV Couplings consistent with SM expectations. 29

30 HIG H ff Combination Combination of H bb and H ττ results. Combined significance of 3.8 σ with a signal strength of 0.83±

31 tth Analysis 31

32 HIG HIG HIG HIG tth - Combination Observed yields and distributions are compared to SM expectations. Median expected combined limit : 95% C.L. in the absence of a signal, 2.9 assuming the presence of SM tth. Observed limit is 95% C.L., reaching sensitivity to SM. 32

33 HIG H Zγ & H γ*γ µµγ HIG Limits at ~10 times the SM cross section for H Zγ and H γ*γ µµ. Only leptonic Z decays used. Loop mediated, sensitive to BSM physics. Need 100 times more luminosity HL-LHC. 33

34 HIG H µµ Lowes branching ratio. Efficiency for final state high. Target for HL-LHC. 34

35 35 HIG BSM Higgs Searches HIG MSSM direct search : φ µµ (w/o b-tag) neutral Higgs production in ττ channel. NMSSM : additional gauge singlet wrt MSSM, one CP-even, one CP-odd. Most recent search h a1a1 4µ

36 HIG BSM Higgs Searches HIG Heavy Higgs from H ZZ 2l2ν, assuming additional EWK singlet added to the SM. Combined limit for Heavy Higgs and A (Type II) 2HDM. α an β determine the cross section for H and A production, the branching ratio Br(H hh), Br(A Zh) and Br(h WW, ZZ, ττ, γγ) Adi Bornheim, CMS Higgs Results, APS Meeting 2014, 36

37 Precision Higgs Physics with HL-LHC FTR Upgrade studies for muon system, assuming increased forward acceptance for H ZZ 4µ High Luminosity LHC aims to deliver 3 ab -1 Precision Higgs physics, di-higgs production, Higgs as a portal. Study for 3 ab -1, A Zh, φ µµ, H ZZ 4l FTR

38 Precision Higgs Physics with HL-LHC Upgrade R&D studies currently ongoing, aiming for a technical proposal later in 2014 or early Track-Trigger Forward Calorimeter & Precision Timing Forward Muon System 38

39 Summary A wide range of Higgs production and decay modes have been analyzed with CMS data. All measured signal strengths and properties are in agreement with expectation for a standard model Higgs boson. The mass measurements are consistent across channels. Precision Higgs physics is opening the door to new territories. Large amounts of luminosity are now needed to reveal the nature of the new boson and its role in fundamental physics. 39

40 Does this answer all our questions? 40