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Report from the Higgs Working Group

Report from the Higgs Working Group. ECFA/DESY LC workshop NIKHEF, Amsterdam 4/4/03. Convenors : M.Battaglia K.Desch A.Djouadi E.Gross B.Kniehl. Fully simulated+reconstructed HZ event (BRAHMS). Introduction. Framework: Understanding the Nature of electro-weak symmetry breaking

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Report from the Higgs Working Group

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  1. Report from the Higgs Working Group ECFA/DESY LC workshop NIKHEF, Amsterdam 4/4/03 Convenors: M.Battaglia K.Desch A.Djouadi E.Gross B.Kniehl Fully simulated+reconstructed HZ event (BRAHMS) Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  2. Introduction Framework: Understanding the Nature of electro-weak symmetry breaking is one of the driving forces in the LC programmme Existence of a light Higgs boson is favoured by experimental data and most theoretical models Exploration of the physics potential of the LC for Higgs physics has three major motivations 1. Make the physics case 2. Give feedback to the design of the detector and the machine 3. Physics “R&D”: learn/don’t forget how to do the analyses Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  3. Introduction • TDR conclusion: Higgs mechnanism can be established in all essential elements • g extended study not essential??? No. • Goals: • - close remaining (but essential) corners • keep up with new theoretical ideas • further study relation to LHC • further study gg option (aA. deRoeck’s talk) • become more realistic in experimental simulation • Group was (and is) very active! • 64 talks (35 exp/29 theo) in 4 workshops • (sorry, I cannot mention all of them…) • Many (but certainly not all) goals achieved – good progress Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  4. Introduction • Plan for this summary: • Profile of a SM-like neutral Higgs Boson • MSSM: additional Higgs Bosons and Sensitivity to Parameters • Extended Models • Relation to the LHC • Thoughts about the Future • Summary and Conclusion Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  5. Profile of a SM-like Neutral Higgs Boson Dominant production processes at LC: Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  6. Profile of a SM-like Neutral Higgs Boson Status of calculations for SM Higgs production and decay: In general in very good shape Recent addition: full EW corrections to WW-fusion Kniehl (LCWS02 review) Denner et al Boudjema et al Jegerlehner et al sizable correction (o(10%)) complicated task, e.g. “Pentagons”: Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  7. Profile of a SM-like Neutral Higgs Boson • Profile of a Higgs boson at the LC: • Mass + Production Cross Sections • Quantum Numbers • Decay Branching Ratios • Top Yukawa Coupling • Double Higgsstrahlung (Self coupling) Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  8. Higgs Profile: Heavier SM Higgs TDR: focus on mH=120,140,160 GeV What, if Higgs mass (somewhat) larger, than EW precision data tell? only WW and ZZ relevant measure width from lineshape? Study of Most promising: final state Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  9. Profile of a SM-like Neutral Higgs BosonMass + Production Cross Section N. Meyer for 500 fb-1@500 GeV mH=240 GeV Also results for 200, 280, 320 GeV available Reconstructed Higgs Mass (GeV) Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  10. Higgs Profile: Quantum Numbers TDR: Spin from threshold scan TDR: CP from angular distributions of ZH New Ideas:Spin from HgZZ CP from transverse polarisation correlations in Hgtt Miller et al Was,Worek Bower Imhof,KD Observable: rr-acoplanarity: First estimate with detector simulation: > 8s separation between CP+ and CP- for 120 GeV Higgs (350GeV/1 ab-1) Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  11. Higgs Profile: Decay Modes Battaglia Richard et al Schreiber et al TDR: for 500 fb-1 , m=120 GeV Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  12. Higgs Profile: Decay Modes New analysis of hadronic BR’s has started using newest tools (ZVTOP, SIMDET4, kinematic fit) T.Kuhl,KD study dependence on vtx layout kinematic selection (Zghadrons and Zgleptons only) not yet optimal preliminary numbers seem to ~confirm TDR numbers Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  13. Higgs Profile: Decay Modes TDR study: obtain BR’s from measuring J-C.Brient Alternative approach: measure fraction of events within an unbiased sample of events disadvantage: smaller event sample advantage : binomial errors smaller than gaussian errors (one measurement instead of two) Results (rel. errors) 500 fb-1@350 GeV mH =120 GeV Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  14. m m Higgs Profile: Rare Decay Modes M.Battaglia • - rises with • a large number Higgs bosons at 800 GeV • test of • ‘lepton universality in Higgs sector’ • select events with two muons and • missing energy: clean signature • - cut on recoil mass (remove ZZ) Result (rel. error) DBR(mm)/BR(mm) = 32 % ΔgHmm = 16 % for 1 ab-1@800 GeV Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  15. Higgs Profile: Rare Decay Modes M.Battaglia Fusion(800GeV) preferred over Higgsstrahlung(350GeV) Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  16. Might add interesting information In case of anomalous gg coupling Most promising channel: Study for: Higgs Profile: Rare Decay Modes Schreiber et al Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  17. Higgs Profile: Rare Decay Modes Summary of rare decays: Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  18. M.Schumacher Invisible Higgs Decays • Many SM extensions predict invisible Higgs Decays, e.g.: • MSSM • Extra Dimensions • Model with new singlets (NMSSM,Majoron Models) • Stealthy Higgs • TDR: Estimate sensitivity from 1 = BR(vis) + BR(invis) • New study: explicit reconstruction in • Assumptions: missing mass Signal(120) Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  19. M.Schumacher Invisible Higgs Decays Result: Result for 500 fb-1@350 GeV (mH=120 GeV): ΔBR/BR(invis) = 10% for BR(invis) = 5% 5σ observation down to BR = 2% Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  20. A.Gay Top Yukawa coupling • - extension to higher masses • and inclusion of HgWW • ANN based selection • event-wise IP-probability tag • results confirmed with SIMDET4+ZVTOP 4 channels analysed: Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  21. Top Yukawa coupling Result: A.Gay for 5% syst. Background uncertainty Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  22. Higgs Self Coupling P.Gay et al TDR: Ds/s=13 % leads to DlHHH/lHHH=23 % (“dilution effect”) (for 1 ab-1 @ 500 GeV) Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  23. New Ideas for Higgs Self Coupling Battaglia,Boos,Yao Additional sensitivity from differential distributions to reduce the dilution: Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  24. MSSM Higgs Sector • Higgs sector of MSSM: 5 physical Higgses: h0, H0, A0, H± • phenomenology determined at tree level by 2 parameters: tanβ and mA. • Higher order corrections from 3rd generation fermions/sfermions important • Crucial prediction: mh<135 GeV • Heavy Higgs Bosons: mAg∞ decoupling limit, h is SM-like • but H,A,H± might as well be within reach of • LC: intense coupling regime • Goal: precise measurements of the observables (Higgs masses, • couplings) to determine the fundamental SUSY parameters • Needs high precision predictions of observables. Theory has not • yet reached this goal. E.g. current theo. uncertainty in mh≈3 GeV Djouadi et al Degrassi et al Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  25. Additional MSSM Higgs Bosons Klimkovich • Analysis for e+e-gHAgbbbb at 500 GeV / 500 fb-1 • SIMDET4 -ZVTOP btagging -kinematic fit • Signals for sin(b-a)=1 and BR(H/Agbb) = 85% : Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  26. Additional MSSM Higgs Bosons Klimkovich Results for e+e-gHAgbbbb at 500 GeV / 500 fb-1 : for sin(b-a)=1 and BR(H/Agbb) = 85% 5s observation up m(A)+m(H) ~ √s-30 GeV Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  27. Additional MSSM Higgs Bosons Raspereza • Analysis for e+e-gHAgbbtt/ttbb at 500 GeV / 500 fb-1 • SIMDET4 -ZVTOP btagging -kinematic fit -Lepton-ID • Signals for sin(b-a)=1 and BR(H/Agbb) = 85% / BR(H/Agtt) = 15% : Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  28. Additional MSSM Higgs Bosons Results for e+e-gHAgbbtt/ttbb at 500 GeV / 500 fb-1 : for sin(b-a)=1 and BR(H/Agbb) = 85% / BR(H/Agtt) = 15% mass resolution ~ 4-8 GeV Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  29. Charged Higgs Battaglia,Ferrari,Kiiskinen,Maki new: now with genuine tbtb background At 800 GeV: 5s discovery up to m=350 GeV Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  30. tanb s<0.01fb s<0.02fb s<0.05fb s>0.05fb mH(GeV) Theory: new calculations to beat kinematic limit Heavy SUSY Higgses: pair production dominant g mass reach limited a explore (supressed) single production modes 1. Charged Higgs: Kniehl et al Moretti et al Weiglein et al • 2. Heavy neutral Higgses • couple ~cos(b-a) in decoupling limit • normally no WW-fusion cross section • Loop effects can enhance the cross section (a bit…) • g (somewhat) higher mass reach than for pair production e+e-gnnHMSSM sqrt(s)=800 GeV Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  31. Constraining the MSSM Higgs sector Ultimate goal: extract the underlying SUSY parameters from Higgs sector measurements from a global fit We’re not there yet: difficult task since at higher orders, Higgs sectors depends on many parameters (stop mixing etc.) Classical example: estimate from BR-measurement Yes! But, BR’s also depend on We should try to bring the bits and pieces together! Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  32. Constraining the MSSM Higgs sector: examples tanb from H/A mA from bb/WW A.Sopczak et al Gross,Heinemeyer, Battaglia, Richard Sensitivity to tanb at 500 GeV/2 ab-1 (mA=200GeV) more ideas: tanb from charged cross section slope Verzegnassi, Trimarchi SUSY corrections (Dmb) from bb/tt Guasch, Hollik, Penaranda Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03 Guasch,Hollik,Penaranda

  33. Constraining the MSSM Higgs sector Ellis,Heinemeyer, Olive,Weiglein Branching ratio deviation in constrained MSSM’s mSugra (also results other constrained scenarios: NUHM, AMSB, GMSB) Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  34. CP violation in the MSSM Higgs sector Frank,Heinemeyer,Hollik,Weiglein Pilaftsis,Wagner,Carena,Ellis MSSM Higgs sector is CP conserving at tree level CP violation enters through sfermion loop if couplings are complex Leads to 3 neutral Higgs mass eigenstates which are not CP eigenstates: Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  35. CP violation in the MSSM Higgs Measure masses and cross sections and scan parameter space assuming Ds=10% and Dm=1GeV (conservative!) T.Klimkovich Sensitivity to CPV parameters from a 3 parameter scan: Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  36. Extended Models • 2HDM • NMSSM • Effects of Extra Dimensions on Higgs sector • Higher Higgs representations Krawczyk, Osland; Gunion Miller, Nevzorov, Zerwas Wells, Hewett, Rizzo, Dominici, Ghosh, Gabrielli, Huitu Huitu Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  37. Extended Models: NMSSM Miller, Nevzorov, Zerwas • NMSSM: additional Higgs singlet • provides viable solution to m-Problem of the MSSM • Singlet introduces new U(1) Symmetry leading to massless • CP-odd Higgs (ruled out) g symmetry must be broken • Phenomenology depends on how strongly the symmetry is broken (slightly broken symmetry = preferred from RG running) • Physical states: 3 CP-even neutral 2 CP-odd neutral 2 charged • a interesting phenomenology Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  38. Extended Models: NMSSM Miller, Nevzorov, Zerwas Example parameters: a e.g. 2 light CP-even Higgses with sizable HZZ coupling a need for study of LC sensitivity to the scenario and its parameters Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  39. Wells, Hewett, Rizzo, Dominici, Ghosh, Gabrielli, Huitu Extended Models: XD effects on Higgs sector • Models with 5D localized gravity (RS model) appear to exhibit a scalar state (connected to excitations of “force” which stabilizes the distance between SM- and Planck-Brane: The Radion • Radion couples to trace of E-p-tensor (= very Higgs-like except for trace anomaly of QCD g ‘tree level’ coupling to gluons • Radion can mix with Higgs boson g two Higgs-like scalars with production cross sections and branching ratios different • from SM Higgs • Rather few model parameters: • - m(Higgs), m(Radion) • - vev of Radion field L • - mixing parameter x Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  40. Dominici, Battaglia, Gunion Extended Models: XD effects on Higgs sector LC ability of precise BR measurements allows to distingiush SM Higgs from mixed state (even if Radion itself is too heavy) theoretically not allowed Red contours:deviation of Hgbb BR > 2.5σ Cyan Region: LHC H discovery Ensured Blue contours: LHC Radion observation in ΦgZZ LC regions complementary to LHC reach theoretically not allowed Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  41. Relation to the LHC • biggest asset of LC Higgs measurements: model independence! • LHC studies (also) improved since TESLA TDR • (e.g. VBF channels allow o(10%) measurement of various • coupling ratios (WW/ZZ, tt/WW,…) or products (tt*bb) • LHC+LC joint interpretation will be useful • example (studied in LHC/LC group): • s(tth)*BR(bb) @ LHC and BR(bb)@LC500 allows reasonable • top Yukawa coupling measurement • Light Higgs precision o(1%) measurements can guide LHC • studies when simultaneous running is ensured • example: sensitivity of h-BR’s on mAg point to mass region • of interest Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  42. Thoughts About The Future • What are the goals for a Higgs working group in the next 2 years?? • Experimental: • Physics studies as crucial input to detector R&D • Reexamine influence of machine parameters (Luminosity, Energy, • Time structure, Backgrounds) on physics performance • Become more realistic in simulation of our benchmark processes • (recoil mass, BR’s, ZHH) • Continue quantitative evaluation of the running options • in gg, eg, e-e- modes (mass reach, light Higgs couplings, …) Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  43. Thoughts About The Future • Facing Experimental Reality: • full simulation (BRAHMS/MOKKA) is now really possible for physics studies • development of appropriate analysis tools might take more time • than the actual physics study (Kin.Fitting, Lepton-ID (esp. t) • algorithms, ISR/BS photon ID, B-tagging, etc. etc.) – but it’s • worth the effort! • Study the dependency of physics observables as a function • of detector/machine parameters (First examples are arriving, • we clearly need more) see e.g. V.Saveliev see e.g. T.Kuhl Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  44. Thoughts About The Future • Theory: • match experimental and theoretical precision. Identify, where particular effort is needed • Watch new theoretical ideas (models with modified H coupling • now easy to explore g general survey?) • General: • International connections – exchange of ideas, codes, common projects etc can still improve! • PhD theses on detector R&D • are much nicer if accompanied by a physics applicability study • (improve possibilities for publications of results?) Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  45. International Connections: an example Ronan Compare and understand differences in three regional simulation programs Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

  46. Summary and Conclusions • Higgs physics is a major pillar of the LC physics case • This case has been further strengthened: • - higher masses carefully studied • - rare Higgs decays • - heavy SUSY Higgs Bosons • - extraction of SUSY parameters from Higgs sector • - sensitivity to extended models • Studies with increased realism in the simulation have started They need be continued to give credible input to detector and machine design • No reason to slow down – only an active community is able to plan and realize the experiment(s)! Klaus Desch, Report from the Higgs Working Group, ECFA/DESY Workshop Amsterdam, 4/4/03

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