1 / 54

Higgs Searches beyond the Standard Model at LHC (and at the B-factories)

Higgs Searches beyond the Standard Model at LHC (and at the B-factories). Michael Kobel TU Dresden DESY Seminars 26.6./27.6.2007. Outline. Status of LHC, ATLAS and CMS Beyond the Standard Model (SM) Higgs MSSM overview Additional Neutral Higgses Additional Charged Higgses

wlarson
Download Presentation

Higgs Searches beyond the Standard Model at LHC (and at the B-factories)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Higgs Searches beyond the Standard Model at LHC(and at the B-factories) Michael KobelTU Dresden DESY Seminars 26.6./27.6.2007

  2. Outline Status of LHC, ATLAS and CMS Beyond the Standard Model (SM) Higgs MSSM overview Additional Neutral Higgses Additional Charged Higgses Invisible Higgses Strong Electroweak Symmetry Breaking Michael Kobel TU Dresden DESY Seminars 26.6./27.6.2007

  3. I. LHC: Descent of the last magnet, 26 April 2007 30’000 km underground at 2 km/h!

  4. LHC: Inner Triplet problem November 2006 • During the pressure test of Sector 7-8 (25 November 2006) the corrugated heat exchanger tube in the inner triplet failed by buckling at 9 bar (external) differential pressure. • The inner triplet was isolated and the pressure test of the whole octant was successfully carried out to the maximum pressure of 27.5 bar, thus allowing it to be later cooled down. • Reduced-height corrugations and annealing of copper near the brazed joint at the tube extremities accounted for the insufficient resistance to buckling. • New tubes were produced with higher wall thickness, no change in corrugation height at ends, and e-beam welded collars to increase distance to the brazed joint. • Installation of these tubes is proceeding in situ.

  5. Inner Triplet repair, Point 5

  6. General schedule • Engineering run originally foreseen at end 2007 now precluded by delays in installation and equipment commissioning. • 450 GeV operation now part of normal setting up procedure for beam commissioning to high-energy • General schedule being reassessed, accounting for inner triplet repairs and their impact on sector commissioning • All technical systems commissioned to 7 TeV operation, and machine closed April 2008 • Beam commissioning starts May 2008 • First collisions at 14 TeV c.m. July 2008 • Pilot run pushed to 156 bunches for reaching 1032 cm-2.s-1 by end 2008 • No provision in success-oriented schedule for major mishaps, e.g. additional warm-up/cooldown of sector

  7. Operation testing of available sectors Machine Checkout Beam Commissioning to 7 TeV LHC General co-ordination schedule, EDMS 102509, 12 June 2007 12 23 34 45 56 67 78 81 Mar. Mar. Apr. Apr. May May Jun. Jun. Jul. Jul. Aug. Aug. Sep. Sep. Consolidation Oct. Oct. Nov. Nov. Dec. Dec. . Jan. Jan. Feb. Feb. Mar. Mar. Apr. Apr. May May Jun. Jun. Jul. Jul. Aug. Aug. Sep. Sep. Oct. Oct. Interconnection of the continuous cryostat Global pressure test &Consolidation Warm up Nov. Nov. Leak tests of the last sub-sectors Flushing Powering Tests Dec. Dec. Inner Triplets repairs & interconnections Cool-down .

  8. ATLAS & CMS • CMS assembled upstairs, lowered in Nov 06- Feb 07 • ATLAS assembled downstairs • finishing installing all sub-detector components before end 2007 • biggest/outermost (muon spectrometer endcaps) and • smallest/innermost (pixel) detectors are last to be installed Michael Kobel, TU Dresden

  9. ATLAS & CMS • Both: Ready for first collisions in time! • ATLAS • CMS Michael Kobel, TU Dresden

  10. II. Electroweak Symmetry Breaking in SM and beyond • Where does the mass come from? Michael Kobel, TU Dresden

  11. The Electroweak Symmetry Breaking (EWSB) • Standard Model (SM) symmetry requires massless particles • *something* has to break this symmetry at t~10-10 sec • A background Higgs field? • then, it must have excitations = Higgs Bosons • can be excited best by massive particles (Z, W, t, or b) • Minimal model: 1 SM Higgs-field and 1 neutral Higgs-Boson • But: many possible alternatives and extensions! Michael Kobel, TU Dresden

  12. Possible Symmetry Breaking Mechanisms Extended Gauge Symmetry Little Higgs, Higgsless, Left-Right Symmetric Model Higgs-Gauge Unification Ryuichi Takashima 2006 J.Lykken, Physics at LHC (Vienna) SUSY (m)SUGRA GMSB AMSB Mirage Split SUSY RPV … Extra-Dimension LED(ADD) Randall-Sundrum Universal ED(KK) … Precision EW data Dynamical Symmetry Breaking Strong EWSB, Chiral Lagrangian, Technicolor, Composite Higgs, Top-quark Condensation Michael Kobel, TU Dresden

  13. II. a. Minimal Supersymmetric Standard Model (MSSM) • More than 1 Higgs-Boson? Michael Kobel, TU Dresden

  14. MSSM on tree level • Minimal Supersymmetry: • 3 neutral Higgs Bosons: h, H, A • 2 charged Higgs Bosons: H+, H- • at tree level, 2 parameters : tan = v2/v1 and mA • Stephen Martin, hep-ph/97-09356 • gMSSM =xgSM Michael Kobel, TU Dresden

  15. MSSM at 2-loop level S.Heinemeyer in J.Ellis et al CERN-PH-TH/2007-012 • Loop level (constrained MSSM): • SUSY breaking parameters, assumed to be unified at some scale : • gluino mass and Higgs mass parameter  Mğand • SU(2) gaugino mass term unified at MGUT  M2 at MEW • sfermion mass terms : unified at MEW  Msusyat MEW • squark trilinear couplings : unified at MEW  A at MEW mixing parameter in the stop sector :  Xt= At -  cot • Total:8parameters • mt=171.4 GeVmeasured • M2, Msusy, Mğ,  and Xtchosen to define a “benchmark scenario” • tan and mA free to vary (tan[1, 60?] and mA[50, 1000]GeV) • Higgs Masses • A ~ degenerate in mass with • h at low masses • H and H± high masses • h mass < 130 GeV (all scenarios) Michael Kobel, TU Dresden

  16. Search strategies • Features of • LargemA and mH: • a = b ± 90° • h is SM-like w/ maximal mass • gMSSM =xgSM • H/A/H±produced via Fermion-couplings! • Large enhancement of SUSY-Higgs ~(tan)2possible • Large tan:b- associated production • Small tan:t- associated production Michael Kobel, TU Dresden

  17. Can we see the additional Higgses? • good news: • at least one Higgs boson observable for all parameters in all four MSSM benchmark scenarios • bad news: • significant area where only lightest Higgs boson h is observable • e.g. Higgs discovery, ATLAS prel., 300 fb-1 (M. Schumacher, hep-ph/0410112, ATL-com-phys-2004-070) Michael Kobel, TU Dresden

  18. II. b. Additional Neutral Higgs Bosons • How to discover? Michael Kobel, TU Dresden

  19. Associate A/H production with b-quarks • Basic 2  2 diagram • Corresponding to b-pdf in Proton • Details much more complex • Add 23, 22, and 21 w/o double counting • Solution: SHERPA MC generator w/ CKKW matchingbetween Matrix Element and Parton Shower contributions • Jet fractions agree with analytic calculation (Harlander+Kilgore) • Example: full (down-type) leptonic modes • b h/H/A  b µ+µ- • b h/H/A  b t+t- b ℓ+νν ℓ-νν • Main backgrounds (several 100 pb) • tt (b)b µ+ν µ-ν tt  (b)b ℓ+ν ℓ-ν • qZ ‘‘b‘‘µ+µ- qZ ‘‘b‘‘t+t- Michael Kobel, TU Dresden

  20. Mass distributions tan b = 15, mA=132 GeV tan b = 15, mA=150 GeV • µ+µ-: excellent mass resolution ~ 3 GeV • still not sufficient to separate h/A/H • t+t-: course mass resolution ~ 40 GeV • need collinear approximation of tau decay M.Warsinsky, Ph.D.thesisDresden, 2007 J.Schaarschmidt, Dipl.thesisDresden, 2007 Michael Kobel, TU Dresden

  21. Expected sensitivity • Best tan b reach: H/A  tt ℓnn hadn(CMS Physics TDRCERN/LHCC 2006-021) • Large tan b, • H/A  µµ mode: • Measure tan bvia Higgs width Michael Kobel, TU Dresden

  22. Additional Charged Higgs Bosons • New input from b-physics! Michael Kobel, TU Dresden

  23. H±, theory • Mass and Couplings: • mH±2 = mA2 + mW2 in MSSMw/ negligible radiative corrections • No coupling to W, Z • Two fermionic couplings dominant: • Minimum tb coupling at tan b = √(mt / mb ) ≈ 7 Michael Kobel, TU Dresden

  24. LEP Limits • Direct LEP limits for e+e-  H+H-stop at ~mW due to W+W- backgr. • MSSM: BR(H±tn) dominant for mH± < mt  mH± >~ 85 – 89 GeV • LEP direct H± limits: • Relevant in non-SUSY 2-Higgs Doublet Models (2HDM) • Marginal in MSSM, since mH±2 = mA2 + mW2 anyway Michael Kobel, TU Dresden

  25. Newly developping constraints from b-decays • Gino Isidori, 3rd Workshop: Flavour in the Era of the LHC, 2006 • Well defined pattern for exp. observables • Starting to give useful constraints • Most limits in literature for 2HDM !No systematic studies for MSSM yet (too many param.!) Michael Kobel, TU Dresden

  26. Radiative bsgPenguins: Theory Shape functionKineticKagan-Neubert O.L.Buchmüller, H.U. Flächerhep-ph/0507253, PRD73 (2006) 073008 • SM prediction from Heavy Quark Effective Theory • Comparison with experiment involves extrapolation in Egvia measured spectral moments • 2 new NNLO calculations 2006: Misiak et al, Becher & Neubert • SUSY contributions via • charged Higgs (also in 2HDM) • stop loops (dep. on mt) ~ Michael Kobel, TU Dresden

  27. Radiative bsgPenguins: Experiments BELLE CLEO • Huge Photon backgrounds: • from p0and h (veto) • from qq continuum (B-ID) • Major players: • BABAR (hep-ex/0607071):(3.94±0.31±0.36±0.21)×10-4 stat syst model • BELLE, CLEO, (LEP) -- kinetic… shape function Michael Kobel, TU Dresden

  28. Comparison to theory • Summary (O.Büchmüller, DPG Heidelberg, 2007) • Naive NNLO theory average: Rbsg = BR(exp)/BR(theory) = 1.16 ± 0.12 • allows 0-40% SUSY contribution on 95%CL Michael Kobel, TU Dresden

  29. B tn: New Physics t± t± ~ ~ rBtn e0tanb » 1 • Leading-order H± contribution! • 2HDM (W.S.Hou, PRD 48 (1993) 2342) • rBtn= BR(2HDM)/BR(SM) = • MSSM (G.Isidori, P.Paradisi, hep-ph/0605012) • Gluino-induced corrections (e0(mg,mq) ~ 10-2)to down-type Yukawa couplings considerable for large tanb • rBtn= BR(MSSM)/BR(SM) = • both cases: A(H±) has opposite sign! • suppression • |A(H±)| < |A(W±)| • (near-)cancellation • |A(H±)| ~ |A(W±)| • (near-)compensation • |A(H±)| ~ 2|A(W±)| • enhancement • |A(H±)| > 2|A(W±)| Michael Kobel, TU Dresden

  30. B tn: Experimental Signature Michael Kobel, TU Dresden

  31. B tn: First Observations C.Bozzi, HCP2007 2.6s Michael Kobel, TU Dresden

  32. B tn: Interpretation Excl.Incl. • SM prediction dependent on fB|Vub| • Interpretation hampered by discrepancy |Vub|incl .vs. |Vub|excl • Inclusive BXuln(4.52 ± 0.19exp ± 0.27theo)x10-3 • Exclusive Bpln(3.60 ± 0.10exp ± 0.50theo)x10-3 • HFAG „Average“ 2006(4.10 ± 0.09exp ± 0.39theo)x10-3 • CKM fit w/o |Vub| (H.Lacker, FPCP07)(3.63 ± 0.09)x10-3 • Avoid |Vub| uncertainty: (G.Isidori, P.Paradisi, hep-ph/0605012) • Scale with Bd mixing  dependence on |Vub / Vtd| (reduced)= (0.99 ± 0.29exp ± 0.08B(Bd) ± 0.12|Vub/Vtd|)x10-3 (my update, using hep-ph/0703035 ) Michael Kobel, TU Dresden

  33. Overall MSSM Fit of b-constraints • G. Isidori, F. Mescia, P. Paradisi, D. Temes: hep-ph/0703035 • 1.01 < Rbsg < 1.24 (1 sigma): blue lines • 0.8 < R‘Btn < 0.9 (future guess!): black lines • current 1-sigma would be 0.7 < R‘Btn < 1.3 • NB: 2nd solution for mH < 200GeV not shown! • B → μ+μ− < 8.0 × 10−8: allowed below green line • DmBs = 17.35 ± 0.25 ps−1 : allowed below gray line • 2 < aμ(exp− SM)/10−9 < 4 : purple lines • Dark Matter (~Bino) density: light blue forbidden M˜q= 1.5 TeV AU= −1 TeVμ = 0.5 TeVM˜ℓ = 0.3 TeV M˜q= 1.5 TeV AU= −1 TeVμ = 1.0TeVM˜ℓ = 0.4 TeV Michael Kobel, TU Dresden

  34. H± at LHC H±(fb) 95 130 170 215 310 mH±(GeV) t± M. Schumacher, ATL-com-phys-2004-070 H± t H± • Two main production processes • for mH±< mt • gg  t t  bW bH± • for mH±> mt • bg  tH± bW H± • Two main decay modes • H± tn, dominant for “small“ mH± • below 200 GeV (large tan b > 10) • below 150 GeV (small tan b) • H± tb,approaches for “large“ tan b • BR(tb)/BR(tn) = (mb/mt)2 ~ 6 Michael Kobel, TU Dresden

  35. H±  tb t H± • Signal: gb(b)  tH±(b)  t tb(b) Wb Wbb(b) • Huge Background: gg  tt+jet  t t“b“  Wb Wb“b“ especially: gg  tt+bb  t tb(b)  Wb Wbb(b) • CMS: Likelihood (kinematics, masses, b-tags) • CMS physics TDR (CERN/LHCC 2006-021): • Discovery reach only for large tan band ideal background knowledge • already small backg systematicsmake it invisible for low LHC Lumi Discovery reach at 30 fb-1 Michael Kobel, TU Dresden

  36. H±  tn tt ---------- • Signal: gb(b)  tH±(b)  t tn(b) Wb tn(b) • Huge Background: gg  tt  Wb W(b)  Wb ℓn (b) especially: gg  tt  Wb W(b)  Wb tn (b) • ATLAS: (B.Mohn, M.Flechl, J.Alwall, ATL-PHYS-PUB-2007-006) • Cut selection with t  had n • Essential cut: DF(ptt , ptmiss) for high pt (flat H±  tn .vs. boosted W  tn from top) Michael Kobel, TU Dresden

  37. H± Discovery reach(ATLAS) • For mH±< mt : coverage for all tanb via tt  bW bH± bW btn • For mH±> mt : coverage for large tanb via tH± bW tn • “Isidori-Paradisi“ region covered w/ 30-300 fb-1 • Mass gap closedby new H± tn analysis • Intermediate tan b:(Hansen, Gollub, Assamagan, Ekelöf: hep-ph/0504216 ) • Decay H± c±1,2c0i 3ℓ+nc01has some coverage in an optimistic scenario: • Max BR(H± c±1,2c0i) • Lowest possible mℓ ~ M.Schumacher, ATL-COM-PHYS 2004-070 Michael Kobel, TU Dresden

  38. II.d. Invisible Higgs • going beyond SUSY Michael Kobel, TU Dresden

  39. H  Invisible? Battaglia, Dominici, Gunion, Wells,hep-ph/0402062 • In SM only small BR(hZZnnnn) ~ 1-1.5% above 180 GeV • Beyond SM (BSM): Noticeable decay rates • MSSM: h,H  Neutralinos, Gravitinos • Large part of interesting parameter space already excluded • Enhanced in scenarios w/o Gaugino mass unification • Massive Neutrinos of 4th Generation (K.Belotzky et al., hep-ph/0210153) • Extra Dimension Models • mixing x with Kaluza-Klein scalars • “Stealthy Higgs“(J.v.d.Bij, ZPC75 (1997) 17, hep-ph/0608245) • N-plet of SM Gauge-singlets φ coupling to Higgs via free coupling ω • Higgs  invisible maybe dominant • Higgs maybe very broad Michael Kobel, TU Dresden

  40. Search at LEP (OPAL) • Signal • High effciency • Background • Separated via mass- dependent likelihood • Systematics via signal- free control samples Michael Kobel, TU Dresden

  41. LEP limits • Stealthy Higgs limits and general cross-section limits • Diplomarbeit A. Ludwig (Bonn/Dresden), OPAL Collab., Eur. Phys. J. C 49 (2006) 457 Michael Kobel, TU Dresden

  42. Search at LHC • Similar problems as for LEP: • Need associated production with “visible” particles • No mass peak, just excess of events • background estimation from data important • Combination of production channels might help to identify invisible object as a Higgs • Discovery/exclusion expressed in parameterx2 = BR(hinv)∙sBSM / sSM • x2 > 1 : exclusion/discovery with SM production impossible • x2 < 1 : sensitivity for BR(hinv) = x2 with SM production Michael Kobel, TU Dresden

  43. ZH channel Michael Kobel, TU Dresden

  44. ttH channel Michael Kobel, TU Dresden

  45. qqH channel (VBF, WBF) Michael Kobel, TU Dresden

  46. Current ATLAS expectations qqHinv F. Meisel et al.: ATL-PHYS-PUB-2006-009, 30 fb-1 • Only qqH channel sensitiv to x2 < 1 for all masses • Studies only done for narrow higgses in ATLAS • Need update (full simulation, trigger,…) • Extremely broad Higgses: ongoing • CMS: all ongoing Michael Kobel, TU Dresden

  47. Extra dimension interpretation • For large higgs-graviscalar mixing x and low MD: • No visible Higgs discovery at LHC (green area) • Instead: invisible Higgs in qqH • Fit from data possible • graviscalar mixing x • Number of extra dim d • ILC helps a lot! qqH invisible >5s Battaglia, Dominici, Gunion, Wells, hep-ph/0402062 and D.Dominici, hep-ph/0408087, based e.g. on S. Abdullin et al. CMS NOTE-2003/033. Michael Kobel, TU Dresden

  48. II.e. Strong Electroweak Symmetry Breaking • Effective Chiral Lagrangian Michael Kobel, TU Dresden

  49. Strong Electroweak Symmetry Breaking q’1 q1 W W W W q2 q2 • ElectroWeak Symmetry Breaking: • Unitarity violation in WLWL scattering at high energy • Standard Model solution • one light Higgs boson • But: hierarchy problem in rad corr to Higgs mass • solution: new physics at TeV scale (SUSY, Extra Dimensions, LittleHiggs, etc.) • if no Higgs !? • solutions: new strong interactions • Technicolor • Compositeness… • General Concept: Chiral Lagrangian Model • low energy effects through values of effective chiral couplings • Dobado et al., Phys.Rev.D62,055011, terms of major importance: • Different choices for magnitude and sign of a4 and a5 correspond to different choices for the underlying (unknown) theory. Michael Kobel, TU Dresden

  50. Chiral Lagrangian Model • The usual EWChL approach doesn’t respect unitarity. • restored by applying different unitarization protocols e.g. • Inverse Amplitude Method (Padé) • N/D protocol, K-Matrix etc. • unitarization procedure  resonances. • position and nature of resonances depend strongly upon the unitarisation procedure.(Butterworth et al., Phys.Rev.D65,096014) Michael Kobel, TU Dresden

More Related