1. Higgs Physics at the Large Hadron Collider Markus Schumacher, Bonn University WE Heraeus Seminar, „New Event Generators“, Dresden, January 2006

2. 2 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 Outline  the SM Higgs Mechanism and Status of Search  SM Higgs Phenomenology and Environment at LHC  Discovery Potential for SM Higgs Boson  Investigation of the Higgs Boson Profile  Phenomenology of SUSY Higgs bosons  Discovery Potential for MSSM Higgs bosons  Discriminating the SM from Extended Higgs Sectors  Conclusion and Outlook

3. 3 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 The Higgs Mechanism in the Nut Shell  consistent description of nature seems to be based on gauge symmetry  SU(2) L xU(1) gauge symmetry  no masses for W and Z and fermions  „ad hoc“ mass terms spoil The problem: renormalisibility  no precise calculation of observables high energy behaviour  e.g. W L W L scattering violate unitarity (probability interpretation) at E CM ~ 1.2 TeV massive gauge bosons: 2 transverse + 1 longitudinal d.o.f. massless gauge bosons: only 2 transverse d.o.f.

4. 4 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 The Higgs Mechanism in the Nut Shell The „standard“ solution: new doublet of complex scalar fields (4 d.o.f.) with appropiately choosen potential V  vacuum spontaneously breaks gauge symmetry  one new particle: the Higgs boson H = v + H (+ 3 d.o.f. for longitudinal components of W and Z) Scalar boson restores unitarity if g HWW ~ M W   const=f(M H )

5. 5 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 Mass generation and Higgs couplings: = v + H  effective mass = friction of particles with omnipresent „Äther“ v =247 GeV x fermion gfgf m f ~ g f v Yukawa coupling M V ~ g v gauge coupling x x W/Z boson g gauge  Interaction of particles with v=247 GeV Fermions g f ~ m f / v W/Z Bosons: g V ~ M V / v  Interaction of particles with Higgs H fermion gfgf x W/Z boson g gauge Higgs v 2 2 VVH coupling ~ vev only present after EWSB breaking !!! 1 unknown parameter in SM: the mass of the Higgs boson 2

6. 6 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 bW ZZ tt  cc gg  Higgs Boson Decays in SM for M<135 GeV: H  bb, dominant for M>135 GeV: H  WW, ZZ dominant tiny: H   also important HDECAY: Djouadi, Spira et al.

7. 7 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006  Theory: from unitarity requirement  M H <~ 1TeV „triviality“  upper bound vacuum stability  lower bound if  New =M Planck  130 < M H <180 GeV What do we know about the Higgs boson mass?  Direct search at LEP: M H <114.4 excluded at 95% CL

8. 8 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 What do we know about the Higgs boson mass?  Indirect: from EW precision measurements (LEP,SLD, TEVATRON …): Corrections depend on masses of heavy particles: top, Higgs M H < 186 GeV (EW fit only) at 95% CL,m top =172.7 GeV M H <219 GeV incl. direct search SM prefers light Higgs boson

9. 9 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 Status of SM Higgs Searches at the TEVATRON Expected sensitivity: 95% CL exclusion up to 130 GeV with 4fb -1 per experiment 3 sigma evidence up to 130 GeV with 8fb -1 per experiment Current sensitivity:: Cross section limits at level of ~ 10 x SM cross section

10. 10 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 1)mass 2)quantum numbers: spin and CP 3)BRs, total width, couplings 4)self coupling at SLHC Higgs Physics at the LHC  discovery of 1 neutral scalar Higgs boson (determination of mass, spin, CP)  discrimination between SM and extended Higgs sectors 1)> 1 neutral Higgs boson 2)charged Higgs boson 3)exotic decay modes e.g. H  invisible 4) … … … direct observation of additional Higgs bosons determination of Higgs profile: deviations from SM prediction

11. 11 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 LHC SPPS pp collisions at the Large Hadron Collider  LHC: proton proton collisions at E CM = 14 TEV, start in 2007 - low luminosity running: 1(2)x10 33 /(cm 2 s)  10(20) fb -1 /year 2 to 3 overlapping events - high luminosity running: 10 34 /(cm 2 s)  100 fb -1 /year ~ 20 overlapping events every 25 ns

12. 12 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 A Toroidal LHC ApparatuS Compact Muon Solenoid el.-mag.calorimetry: H  2 photons, H  ZZ  4 electrons mass resolutions: : 0.7 to 1.5 % 4e: 1.3 to 1.8% spectrometer + tracking det.: H  ZZ  4 muons mass resolution: 0.6 to 1.1 % vertex + tracking detectors: ttH, H  bb b-tagging performance overall calorimetry: H  , H  WW  ll, VBF prod. missing E. resolution, hermiticity, forward jets  calorimetry to  = 5

13. 13 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 Production of the SM Higgs Boson at LHC

14. 14 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 QCD corrections and Knowledge of Cross Sections  K =  NNLO / LO ~2   = 15% from scale variations  error from PDF uncertainty ~10% Caveat: scale variations may underestimate the uncertainties! ttH: K ~ 1.2 ~ 15% WH/ZH: K~1.3 to1.4 ~7% VBF: K ~ 1.1  ~ 4% + uncertainties from PDF (5 to 15%)  but: rarely MC at NLO avaiable (except gluon gluon fusion)  background: NLO calculations often not avaiable  need background estimate from data  ATLAS: use K=1 and LO MC for signal and background for now  CMS: apply K-factor for GGF production a. „guestimated“ K for BG e.g.: Gluon Gluon Fusion Harlander et al.

15. 15 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 Cross sections for background processes Higgs 150 GeV: S/B <= 10 -10 overwhelming background  trigger: 10 -7 reduction on leptons, photons, missing E p p q q q pp q q q q H WW l l Background: mainly QCD driven Signal: often electroweak interaction  photons, leptons, … q

16. 16 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 Considerations for Discovery Channel Choice  efficient trigger (need photon, lepton, muon, …)  no fully hadronic final states: eg. GGF, VBF: H  bb  reconstruction of Higgs boson mass possible? yes: H  gg, ZZ, no: H  WW  background suppressable and controlable - good signal-to-background ratio, small BG uncertainty - estimate from data possible (sidebands, control samples) - some channels: shape prediction from MC  evaluation of discovery potential: stable cross section prediction and MC generator avaiable  MC studies with fast detector simulation  key performance numbers from full sim.: b/tau/jet/el.// ID, isolation, jet veto, mass resolutions, trigger, …  both collaborations plan updated evaluation with current software, newest detector layout and MC event generators within next year

17. 17 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 H  2 Photons  signature: two high P t   background: irreducible pp   +x reducible pp  j, (jj), …  exp issues (mainly for ECAL): , jet separation - energy scale, energy + angular resolution - conversions/dead material  mass resolution  M /M= 0.7% dead material: (un)converted  underlying event: vtx constraint precise background estimate from sidebands (O(0.1%)) expected S/BG ~ 1/10 CMS 100fb -1 LO  NLO: increase of S/  B ~ 50  60% NLO

18. 18 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 Gluon Fusion: H  ZZ (*)  4 Leptons  signature: 4 high p t isolated leptons 1(2) dilepton mass ~ M Z  irreducible BG: ZZ  mass reconstruction  reducible BG: tt, Zbb  4 leptons  rejection via lepton isolation and b-veto  good mass resolution  M : <~1%  small and flat background  easy estimate from data CMS 100fb -1 NLO

19. 19 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 Gluon Fusion: H  WW  l l ATLAS M=170GeV 30fb -1  signature: - 2 high p t leptons + large missing E T - lepton spin corrleations - no mass peak  transverse mass transverse mass  BG: WW, WZ, tt lepton iso., missing E resolution jet (b-jet) veto against tt  BG estimate in data from  ll  NLO effect on spin corr.  gg  WW contribution signal like Dührssen, prel.  ll

20. 20 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 ttH with H  bb  mass resolution  M : ~ 15%  50% correct bb pairings  very difficult background estimate from data with exp. uncertainty ~ O(10%)  normalisation from side band  shape from „re-tagged“ ttjj sample  reducible BG: tt+jets, W+jets  b-tagging irreducible BG: ttbb  reconstruct mass peak  exp. issue: full reconstruction of ttH final state  combinatorics !!! need good b-tagging + jet / missing energy performance S/BG ~ 1/6 30 fb -1 only channel to see H  bb ATLAS  signature: 1 lepton, missing energy 6 jets of which 4 b-tagged

21. 21 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 Vector Boson Fusion: pp  qqH Jet  signature: -2 forward jets with large rapidity gap - only Higgs decay products  in central part of detector   Forward tagging jets Higgs Decay

22. 22 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 Vector Boson Fusion: pp  qqH  2 forward tagging jets with rapidity gap: p T >20GeV forward jet reconstruction ATLAS High Lumi Low Lumi jet-veto fake rate due to pile up ATLAS  theory questions: jet distributions at NLO? esp. direction of 3rd jet? efficieny of central jet veto?  need NLO MC generator for signal and BG influence of underlying evt?  experimental issues:  

23. 23 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006  signature: tagging jets + - 2 high p t leptons + large missing E T - lepton spin corrleations (spin1  0) - no mass peak  transverse mass Weak Boson Fusion: H  WW  ll (lqq) tt, Wt, WWjj,...  backgrounds: H  WW  e ATLAS 10 fb -1 M H =160 GeV  S/BG ~ 3.5/1   BG ~10% shape from MC normalisation from side bands in M T and  ll central jet veto, b-veto CMS 60 fb -1

24. 24 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 Vector Boson Fusion: H  tau tau  ll 4 or l had 3  signature: tagging jets + - 2 high p t leptons (1 l, 1 tau) + large missing E T - mass reconstruction despite 4 (3) in collinear approximation  backgrounds: tt,Zjj central jet vetoreconstruction of m  large boost of tau  tau, lepton, neutrino directions same mass resolution ~ 10% (5 % from acollinear approximation) dominated by missing E. resolution

25. 25 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 ATLAS H    e  Vector Boson Fusion: H  tau tau  ll 4 or l had 3 expected BG uncertainty ~ 5 to 10% for M H > 125 GeV: flat sideband for M H < 125 normalisation from Z peak, but shape? channel so far only studied für M H >110 GeV: how far down sensitive? mass determination possible? 30 fb -1 lepton hadron lepton

26. 26 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 Vector Boson Fusion, H  estimate of BG shape from data  Idea: jjZ  andjjZ     look almost the same, esp. in calos  same missing energy only momenta different  Method: select Z   events randomise momenta apply „normal“ mass reco. PT miss,final (GeV)M  (GeV) promising prel. results from ongoing diploma thesis in BN (M. Schmitz)

27. 27 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 Discovery Potential for light SM Higgs boson excluded by LEP for GGF: raise of significance by ~ 50% from LO to NLO results for cut based analysis  improvement by multivariate methods

28. 28 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 Discovery Potential for light SM Higgs boson For M H >330 GeV also: VBF: H  ZZ  ll VBF: WW  lqq excluded by LEP discovery from LEP exclusion until 1 TeV  from combination of search channels with 15 fb -1 of well understood data  with individual search channels with 30 fb -1 of well understood data

29. 29 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 Measurement of Higgs Boson Mass ATLAS M/M: 0.1% to 1%  Uncertainties considered:  “Indirect” from Likelihood fit to transverse mass spectrum: H  WW  ll WH  WWW  lll  Direct from mass peak: H  H  bb H  ZZ  4l VBF with H   or WW not studied yet ! i) statistical ii) absolute energy scale 0.1 (0.02) % for l,,1% for jets iii) 5% on BG + signal for H  WW

30. 30 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006  sensitivity through spin correlations of Higgs decay products  one possibility H  ZZ  4 leptons Spin and CP Quantum Numbers: 0 even in SM : angle btw. decay planes :angle btw. leptons and Z in Z rest frame (Gottfried Jackson angle) Higgs rest frame  observation of H  or gg  H rules out Spin=1 (Young theorem) L (T) ratio of longitudinal (tranverse) polarised Z bosons 100 fb -1

31. 31 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 Spin and CP Quantum Numbers: discrimination power  alternative methods: decay: H   via spin correlations production: i) ttH angle between t,t,H ii) VBF  btw. tagging jets        discrimination dominated by  for masses > 250 GeV  seperation power > 2  for all spin, CP hypothesis and M H >200 GeV  currently under study: - NLO effects - verification with full sim. + all BGs - lower masses H  ZZ*

32. 32 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 Determination of Higgs boson couplings Loop induced effective couplings: (sensitive to new physics) Photon: g  = g W “+“ g t “+“… Gluon: g  = g t “+“ g b “+“… H x x Born level couplings: Fermions g f = m f / v W/Z Bosons: g V = 2 M V / v 2  couplings in production  Hx = const x  Hx and decay BR(H  yy) =  Hy /  tot  experiment: rate = N sig +N BG N sig = L x efficiency x  Hx x BR  need to know: luminosity, efficiency, background  Hx x BR ~  HX  Hy  tot prod decay partial width:  Hz ~ g Hz 2  tasks: - disentangle contribution from production and decay - determine  tot

33. 33 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006  ratios of BRs = ratios of  = ratios of g, if only Born level couplings e.g. 9 fit parameters: all rates can be expressed by those 9 parameters H  WW chosen as reference as best measured for M H >120 GeV For 30fb -1 worse by factor 1.5 to 2 13 analysis used Ratio of Partial Widths   including various exp. and theo. errors

34. 34 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 Total Decay Width  H  for M H >200 GeV,  tot >1GeV  measurement from peak width in ZZ  4 l  upper limit needs input from theory: mild assumption: g V <g V SM valid in models with only Higgs doublets and singlets rate(VBF, H  WW) ~  V 2 /  tot < ( V 2 in SM)/  tot   tot < rate/( V 2 in SM)  lower limit from observable rates:  tot >  W + Z + t + g +....  for M H <200 GeV,  tot << mass resolution  no direct determination  have to use indirect constraints on  tot

35. 35 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 Absolute couplings with g V < g V SM constraint  coupling to W, Z, , b, t g/g = ½ g 2 )/g 2   inv for undetactable decays e.g. c, gluons,new   photon (new),  gluon (new): non SM contribution to loops g/g = ½ g 2 )/g 2 Dührssen et al.

36. 36 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 M H 2 =  2 =M Planck Motivation for Supersymmetry from Higgs Sector  Higgs problem in SM: large corrections to the mass of the Higgs-Boson 2  “solves” hierarchy problem: why v=246 GeV << M Pl =10 19 GeV ? M H 2 = (M SM- M SUSY ) 22 WW + H H  natural value ~ M Pl  electroweak fit M H ~O(100GeV)  SUSY solution: - partner with spin difference by ½ cancel divergence exactly if same M - SUSY broken in nature, but hierarchy still fine if M SUSY ~1 TeV H H   -  SUSY breaking in MSSM: parametrised by 105 additional parameters too many  constrained MSSM with 5 additional parameters

37. 37 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 The MSSM Higgs sector in a tiny Nut Shell  SUSY: 2 Higgs doublets  5 physical bosons real MSSM: 2 CP even h, H, 1 CP odd A, charged H +, H -  at Born level 2 parameters: tan, m A m h < M Z  large loop corrections from SUSY breaking parameters m h < 133 GeV for m top =175 GeV, M SUSY =1TeV  corrections depend on 5 SUSY parameters: X t, M 0, M 2, M gluino,  fixed in the benchmark scenarios e.g. MHMAX scenario  maximal M h  conservative LEP exclusion  t b/ W/Z h cossin-sincossin() H sinsincos/coscos() A cottan -----  g MSSM = g SM no coupling of A to W/Z small   small BR(h  ,bb) large    large BR(h,H,A  ,bb)  = mixing btw. CP-even neutral Higgs bosons

38. 38 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 Discovery Potential in the tanversus M A Plane  LEP tan exclusion: no exclusion for m t larger ~183 GeV !  TEVATRON: so far exclusion for tan > 50 M A <200GeV  ATLAS: calculations with FeynHiggs  CMS: HDECAY with SUBHPOLE up to now  no systematic uncertainties yet main questions for LHC:  At least 1 Higgs boson observable in the entire parameter space?  How many Higgs bosons can be observed?  Can the SM be discriminated from extended Higgs sectors? 4 CP conserving benchmark scenarios considered: Carena et al., Eur.Phys.J.C26,601(2003) 1)MHMAX 2) No mixing 3) Gluophobic 4) small  conclusions the same due to to complementarity of search channels M top =174.3 GeV

39. 39 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 Influence of Benchmark Scenarios  reduced couplings e.g. small  scenario  small g hbb and g h  reduced sensitivity discovery via VBF, h  tt tth, h  bb  different M h in same (tan,M A ) point  change of sensitive channels - FeynHiggs: maximum value 133 GeV - SUBHPOLE: (less corrections) 127 GeV

40. 40 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 h or H observable with 30 fb -1 Vector Boson Fusion: 30 fb -1 studied for M H >110GeV at low lumi running ATLAS preliminary

41. 41 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 Small  scenario versus MHMAX Scenario, h: 30 fb -1  small „hole“ covered by complementarity of search channels ATLAS preliminary ATLAS preliminary  remaining differences due to different M h (11 GeV between MHMAX and small) -VBF, H  border at low tan given by M h =110 GeV contour - tth, H  bb: significance decreasing rapidly with increasing M h

42. 42 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 Light Higgs Boson h  large area covered by several channels   sure discovery and parameter determination possible  small area uncovered @ m h ~ 95 GeV 300 fb -1 30 fb -1  VBF dominates observation  small area from bbh,H   for small M h ATLAS preliminary

43. 43 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 CMS: Light Higgs Boson h

44. 44 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 Heavy Neutral Higgs Bosons H and A  decay modes: H/A   and H/A  enhanced with tan  dominant production: bbH(A) (NLO studies on the way: how to handle correctly bb  H, gb  bH, gg  bbH) : BR ~ 10 % M ~ 12% BR~ 0.04% M ~ 1% intense coupling regime:  only  might resolve several mass states ~ (tan) 2  exp. challenges: b-tag, tau-tag, E miss res.  mass res.

45. 45 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 H/A  and  H/A   ATLAS 30fb -1 larger mass: also   had. had. trigger on hard tau jets Eff.(LV1TR)= 80% =95% offline selected evt. Tau ID: eff(tau)=55% rejection(QCD)=2500 H/A    e  (only CMS) H/A    had had

46. 46 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 Discovery Potenital for H and A ATLAS preliminary intermediate tanregion not covered by SM decay modes

47. 47 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 Charged Higgs Bosons gb  H +- t  low mass: m H+- < m top gg  tt tt  H +- bW  high mass: m H+- > m top  running bottom quark mass used, Xsec for gb  tH +- from T. Plehn‘s program Production:  transition region around m top and from 2to2 to 2to3 process needs revised experimental analysis, are MC generators ready?  decay modes: H  (~100% below m top, ~10% above) H  tb (~90% above threshold) gg  btH+- contributes to NLO of gb  tH+- avoid double counting correct handling of region around mtop

48. 48 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 Charged Higgs Bosons ATLAS preliminary tt  bbWH + W  qq H +-   ATLAS

49. 49 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 Overall Discovery Potential: 300 fb -1  at least one Higgs boson observable for all parameters in all CPC benchmark scenarios  significant area where only lightest Higgs boson h is observable  can H  SUSY decays or Higgs from SUSY decays provide observation? discrimination via h profile determination? similar results in other benchmark scenarios VBF channels, H/A  only used with 30fb -1 300 fb -1 ATLAS preliminary

50. 50 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 Higgs Decays to Gauginos M sleptons =250 GeV M sleptons = 110 GeV gb  tH +, H    2,3 0  1,2   3l+E T miss H 0   2 0  2 0  4l+E T miss e.g. H 0   2 0  2 0   1 0  1 0 +4l dominant background from SUSY results for most optimistic scenarios shown  fine tuned require small slepton masses for large BR( 2   1 n leptons) reduced sensitivity for other channels, consistent interpretation needed

51. 51 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 ATLAS prel. 300 fb -1 SM or Extended Higgs Sector e.g. Minimal SUSY ? discrimination via rates from VBF R = BR(h  WW) BR(h  )  assume Higgs mass well measured  no systematic errors considered compare expected measurement of R in MSSM with prediction from SM for same value of M H =|R MSSM -R SM | exp

52. 52 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 The Higgs Sector in the CP Violating MSSM mass eigenstates H 1, H 2, H 3 <> CP eigenstates h,A,H  at Born level: CP symmetry conserved in Higgs sector  complex SUSY breaking parameters (,A t ) introduce new CP phases  mixing between neutral CP eigenstates  no a priori reason for real SUSY parameters  baryogenesis: 3 Sacharov conditions B violation : via sphaleron processes CP violation : SM too less, CPV MSSM new sources  fine No therm. Equ. : SM no strong 1st order electroweak phase transition CPV MSSM still fine (even better NMSSM)  evade dipole moments via spurious cancellations or split SUSY Why consider such scenarios?

53. 53 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 Phenomenology in the CPX scenario  H 1,H 2, H 3 couple to W,Z  all produced in VBF H3 H2 H1  H 2,H 3  H 1 H 1, ZH 1, WW, ZZ decays possible  no limit for mass of H 1 from LEP (compare CPC MSSM: M h >M Z )  maximise effect  CPX scenario (Carena et al., Phys.Lett B495 155(2000)) arg(A t )=arg(A b )=arg(M gluino )=90 degree  scan of Born level parameters: tan and M H+- LHWG-Note 2005-01

54. 54 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 CP-Violating MSSM: Overall Discovery Potential M H1 : < 70 GeV M H2 : 105 to 120 GeV M H3 : 140 to 180 GeV small masses below 70 GeV not yet studied in ATLAS 300 fb -1  most promising channel: tt  bW bH +, H +  W H 1, H 1  bb final state: 4b 2j l same as ttH, H  bb (study in Bonn)  revised studies for H 2/3  H 1 H 1 also interesting  yet uncovered area  size and location of „hole“ depends on M top and program for calculation ATLAS preliminary

55. 55 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 Very first look at new promising MC study M H+ =135 GeV, M H1 =54GeV, tan=4.8 (diploma thesis M. Lehmacher, BN)  estimate of background from data seems difficults  coverage of „hole“ area incl. systematics under study!  t t  H + b W b H +  W H 1 H 1  bb  same final state as ttH, H  bb1: 4b 2q l Emiss  reconstruct top quarks  combinatorics

56. 56 Markus Schumacher Higgs Physics at the LHC WE Heraues Seminar, Dresden, January 2006 Conclusion and Outlook  Standard model: discovery of SM Higgs boson with 15 fb -1 requires good understanding of whole detector multiple channels with larger luminosity  Higgs profile investigaton  CP conserving MSSM: at least one Higgs boson observable only h observable in wedge area at intermediate tan maybe Higgs to SUSY or SUSY to Higgs observable? discrimination via Higgs parameter determination seems promising  CP violating MSSM: probably a „hole“ with current MC studies promising MC studies on the way  more realistic MC studies: influence of miscalibrated and misaligned detector improved methods for background estimation from data use of NLO calcluations and MCs for signal and background  additional extended models + seach channels: CPV MSSM, NMSSM, 2HDM Higgs  SUSY, SUSY  Higgs VBF, H  bb (b-trigger at LV2), VBF,H  inv. (add. forward jet trigger)