Searches at LEP Ivo van Vulpen CERN Moriond Electroweak 2004 Ivo van Vulpen CERN On behalf of the LEP collaborations

LEP and the LEP data Outline of the talk e otica iggs searches  LEP: e+e- collider at s  mZ (LEP1) and s = 130-209 GeV (LEP2) Most results (95% CL limits) based on LEP2: Int. Lum.  2.6 fb-1 4 experiments: Aleph, Delphi, Opal and L3 Outline of the talk USY searches iggs searches e otica Moriond EW 2004 Ivo van Vulpen

Higgs Searches http://lephiggs.web.cern.ch/LEPHIGGS/www/Welcome.html Moriond EW 2004 Ivo van Vulpen

Higgs Searches covered in this talk  SM Higgs boson  General 2HDM MSSM (CP-conserving)  3 benchmarks  Flavour independent  Charged Higgs boson  MSSM (CP non-conserving)  Fermiophobic  Invisible Higgs boson  Not covered: MSSM Gluophobic (LHC), Double charged Higgs bosons, Anomalous Higgs couplings, Yukawa Higgs production, Extended Models, many many more …… Moriond EW 2004 Ivo van Vulpen

SM Higgs boson  h In the SM we know everything about the Higgs boson Higgs Searches SM Higgs boson Higgs strahlung h In the SM we know everything about the Higgs boson (except its mass) mh > 115.3 GeV (expected)  mh > 114.4 GeV (observed) Weak boson fusion Excess at 115 GeV: -2ln(Q) at mh = 115 GeV 100,000 signal+background experiments (MC) Exclusion on HZZ coupling 100,000 background-only experiments (MC) LEP data Moriond EW 2004 Ivo van Vulpen

Two Higgs Doublet Models (2HDM) Higgs Searches Two Higgs Doublet Models (2HDM)  Simplest extension of the SM: Add 2 complex Higgs Doublets (H1, H2) Parameters: tan() (=v1/v2) ,  (=mixing h0,H0) + Higgs boson masses Higgses: 2 CP-even: h0, H0 Models: 2HDM(I): One doublet for all fermions 1 CP-odd: A0 2HDM(II): One up-type doublet 2 charged: H+,H- One down-type doublet MSSM Neutral Higgs boson production: Higgs boson decay: h h A Depends on model parameters couples to mass, so mainly: Higgs strahlung Associated production Moriond EW 2004 Ivo van Vulpen

Tree-level parameters Higgs Searches Higgs Searches MSSM 7 parameters Tree-level parameters tan() Higgs vev ratio mA Mass of CP-odd Higgs Three benchmark scenarios: 1) mh-max (max mh for each tan() ) Loop-level parameters 2) no-mixing (in the stop sector) A Trilinear Higgs-sfermion coupling 3) large- (H in reach, but regions with reduced bb couplings) mg Mass of the gluino  Higgs mass parameter msusy Sfermion mass at EW scale M2 Gaugino mass at EW scale Moriond EW 2004 Xt = stop mixing = At -  cot() Ivo van Vulpen

MSSM benchmark (large ) Higgs Searches Higgs Searches MSSM benchmark (large ) Flavour independent Higgs bosons Mass exclusion using SM(hZ): mh > 113.0 GeV (expected) mh > 112.9 GeV (observed) 2.3 GeV worse than SM Higgs DELPHI hA -> hadrons (preliminary) Model independent mS1 mS2 100% 10%  OPAL also made a decay mode independent search hZ hA  Lightest Higgs: mh < 108 GeV  Reduced couplings to bb Higgs decays to cc or gluons LEP combined: 88-209 GeV  Adding flavour independent excludes large- scenario unexcluded Moriond EW 2004 Ivo van Vulpen

Mh-max MSSM benchmarks No-mixing Higgs Searches Higgs Searches Mh-max MSSM benchmarks No-mixing hZ small hA kinem. out of reach hZ hA Mh>2mA: h->AA dominant Extend searches for h->AA (mA<mb) and H+ Scenario mh mA Excluded tan() No mixing >91.5 >92.2 0.7 < tan() < 10.5 Mh-max >91.0 >91.9 0.5 < tan() < 2.4 conservative tan() exclusion depends strongly on the top mass Moriond EW 2004 Ivo van Vulpen

mh ~  Influence of the top mass on tan() exclusion region: In MSSM benchmarks: mtop = 175 GeV Maximum mh: in the MSSM  135 GeV ~ Computation of mh-max: Loop corrections  m4top FeynHiggs: higher order corr. -> mh  3 GeV mh-max benchmark scenario mtop  5 GeV -> mh  5 GeV mh  If mtop is larger than 175 GeV, the LEP-excluded tan() region shrinks Depends on results from CDF & D0 --> K. Bloom & Y.Kulik (this session) Moriond EW 2004 Ivo van Vulpen

CP non-conserving scenarios Higgs Searches Higgs Searches MSSM CP non-conserving scenarios  Break CP symmetry by radiative corrections Low mass regions open up CP conserved: (H1, H2) -> mass eigenstates are CP-eigenstates tan() versus mH1 h,H (CP-even), A (CP-odd) e+e- -> hZ and e+e- -> hA CP: H1, H2 H3 are mass-, but not CP-eigenstates t,b ˜ ˜ h,H H1 Note: only h,H (CP-even) couple to Z. A Different CP-phase A tan() M2  m4top Im (,At) / v2 m2susy OPAL CP benchmark: CPX Scan parameters: tan() and mH+ mH1 (Msusy = 500 GeV, =4 Msusy, |At,b|=|mg|=2 Msusy ) Moriond EW 2004 Ivo van Vulpen

Fermiophobic Higgs bosons Higgs Searches Fermiophobic Higgs bosons  In 2HDM (I) models Higgs couplings to fermions can be close to 0  Decays to photons (W-loop) is dominant  h Z mh > 109.7 GeV (observed)  WW ZZ* 100 GeV Roughly 100 times SM prediction Moriond EW 2004 Ivo van Vulpen

Invisible Higgs bosons Higgs Searches Invisible Higgs bosons  MSSM: Higgs boson might decay into Expected Cross section h LEP combined stable Excluded Cross section Mh > 113.5 GeV (exp.) Mh > 114.4 GeV (obs.) Moriond EW 2004 Ivo van Vulpen

Higgs boson summary: Observed Lower limit on mh (GeV) Higgs scenario SM Higgs 114.4 GeV MSSM (h) 91.0 GeV MSSM (A) 91.9 GeV Flavour independent 112.9 GeV Charged Higgs bosons 78.6 GeV Fermiophobic 109.7 GeV Invisible 114.4 GeV Moriond EW 2004 Ivo van Vulpen

SuperSymmetry http://lepsusy.web.cern.ch/lepsusy/ Moriond EW 2004 Ivo van Vulpen

SUSY model covered in this talk SUSY Searches SUSY model covered in this talk  R-parity conservation there is a stable Lightest Supersymmetric Particle (LSP) SUSY particles are produced in pairs  Mass universality at the GUT scale sfermions (m0) cMSSM gauginos (m1/2) 8 parameters: m1/2, m0, tan(), , mA and Af(At, Ab, A)  SUSY broken by gravitation (SUGRA): Signature: Missing energy (escaping neutralino) and dependence on M (msparticle- mLSP) This talk: Results on sleptons, squarks, charginos --> lower limit on the mass of the LSP Last slide: Results on R-parity violation, GMSB. Moriond EW 2004 Ivo van Vulpen

sleptons e e e+ e- M  production M small SUSY Searches sleptons  production M small e e Z/ e+ e- cross sections for lR smaller than lL  decay M  = -200 GeV and tan() = 1.5 very soft leptons  Mass limits: Lower limits in GeV = 0 GeV 99.6 94.9 85.9 85.0 from the Z = 40 GeV 99.4 96.5 92.5 91.7 Moriond EW 2004 Ivo van Vulpen

squarks e+ e- sbottom  production:  (main) decays SUSY Searches  production:  (main) decays squarks stop sbottom Z/ e+ e- sbottom stop Mixing in 3rd family: M< mc: squark is a quasi-stable particle  Signature: acoplanar jets + E and P  Mass limits (in GeV): M = 20 GeV & for (non)-decoupled from Z Mass limit 100 (98) 99 (96) 99 (95) Moriond EW 2004 Ivo van Vulpen

new A light sbottom cos mix SUSY Searches new A light sbottom Excess in bb cross section at the Tevatron: How about a 12-16 GeV gluino and 2-5.5 GeV sbottom ?? P.Janot hep-ph/0403157  Moriond 2003: (ALEPH) Stable sbottoms: Msbottom> 92 GeV  Hadronic cross section data from: LEP1, LEP2 and PEP, PETRA, TRISTAN, 95% CL lower limit on msbottom (GeV) Small coupling sbottom to Z The older generations in the LEP family help out (use s = 20-209 GeV) Hadronically decaying sbottom: Msbottom > 6.0 GeV cos mix Moriond EW 2004 Ivo van Vulpen

Charginos: large m0 e+ e+ e- e-  W+ l+ Small m0: light sfermions Large cross section in large part of parameter space  production e+ e- Z/ e+ e-  decay  l+ W+ Negative interference if chargino is gaugino W-> qq (68%) / lv (32%) 1) M > 3 GeV: LEP combined 2) 200 MeV < M < 3 GeV: low momentum particles (use ISR -> high PT-) 3) M < 200 MeV: ‘kinky’ tracks and displaced vertices Long lived charged particles (dE/dx information) Moriond EW 2004 Ivo van Vulpen

SUSY Searches The LSP cMSSM  Interpret the combined results in the cMSSM framework Combining results from Higgs searches with slepton, chargino and neutralino searches Use cMSSM mass relations  m0 large m0 small Assuming m0 < 1 TeV and mtop = 175 GeV and no stau mixing Moriond EW 2004 Ivo van Vulpen

The LSP mSUGRA MSUGRA = cMSSM + 1) common scalar mass (mA via m0) SUSY Searches The LSP mSUGRA  Interpret the combined results in the mSUGRA framework MSUGRA = cMSSM + 1) common scalar mass (mA via m0) + 2) common trilinear coupling at GUT (At, Ab, A = A) + 3) fix || (EW symmetry breaking) ( -> sign()) 5 parameters: m1/2, m0, tan(), sign(), A  Assuming m0 < 1TeV A=0, mtop = 175 GeV A=0, mtop = 180 GeV positive 59.0 53.9 50.8 negative 58.6 52.0 50.3 A 0 0 any sign() mtop 175 180 175 Any A mtop = 175 GeV Moriond EW 2004 Ivo van Vulpen

SUSY summary:  Not shown: AMSB & scenarios where the sneutrino or the gluino is the LSP Moriond EW 2004 Ivo van Vulpen

Extra dimensions Low scale gravity in Data/MC MH> 1.20 TeV (= +1) Exotica Searches Low scale gravity in Extra dimensions  Gravity strong near the EW scale Data/MC n extra (space) dimensions of radius r  Virtual graviton exchange affects:  Put limits on MH (gravitational mass scale): MH> 1.20 TeV (= +1) cos(e) MH> 1.09 TeV (= -1)  Not shown: technicolour, single top, leptoquarks, excited fermions, Z’, cont. interactions, 4th generation quarks … Moriond EW 2004 Ivo van Vulpen

Conclusions: Rest of the cheese is for the Tevatron & LHC  SM Higgs combined and published Searches for SUSY Higgs bosons -> exclude large part of MSSM parameter space Final benchmark scans this summer (also gluophobic – interesting for LHC)  LEP combined searches for sparticles Interpretations in a wide variety of SUSY models Rest of the cheese is for the Tevatron & LHC Moriond EW 2004 Ivo van Vulpen

Backup slides Moriond EW 2004 Ivo van Vulpen

Hypotheses testing: Likelihood ratio method Higgs Searches Hypotheses testing: Likelihood ratio method  Construct 2-dim distr. for background(mh) and signal(mh)+background --> (Mhrec, ) Higgs mass estimator  For each event i -> you know wi = P(s+b)/P(b) separating variable  Define test-statistic as –2ln(Q), with Q = Ls+b / Lb (=i wi) with weights Number of expected signal events Ratio of the expected number of signal events over the expected number of signal events in a locql bin of (Mhrec, ) Number of selected candidates 100,000 signal+background experiments (MC) 100,000 background-only experiments (MC) The rules: LEP 1-Clb: incompatibility with the background-only hypothesis 1-Clb < 2.7 10-3 --> 3 sigma 1-Clb < 5.7 10-7 --> Nobel Prize ! CLs+b: compatibility with the signal+background hypothesis 1-Clb Cls+b CLs: compatibility with a signal hypothesis. CLs  CLs+b/CLb Cls < 0.05 --> Signal hypoth. excluded ‘at 95% CL’ Moriond EW 2004 Ivo van Vulpen

Charged Higgs bosons Excluded But … unfortunately Higgs Searches Charged Higgs bosons  Assumption of fermion decay is not valid in unexcluded 2HDM(II) no-mixing point Br(H+-> AW+*) can be 60% Analysis: only for mA>12 GeV (bb) mA < 12 GeV --> special effort Extended h->AA reach (A->cc/+-/gluons) BR(H--> ) Excluded WW background OPAL Mh > 78.8 GeV (exp.) Mh > 78.6 GeV (obs.) Excluded LEP1 Excluded But … unfortunately Included in next (final?) benchmark scan Moriond EW 2004 Ivo van Vulpen

Neutralinos neutralino decay e+ e+  e- Z e-  neutralino production SUSY Searches Neutralinos  neutralino production neutralino decay  e+ e- Z e+ e- Z Positive interference if neutralino is gaugino Z-> qq (70%) / v v (20%) / ll(10%)  Phenomenology depends on M, but also on m0 (common sfermion mass at GUT scale) Moriond EW 2004 Ivo van Vulpen

Exotica Excluded * * e*  Excited leptons: Fermion sub-structure: (compositness scale in TeV region) Excluded Decay: l* -> l / lZ / W * * More sensitive due to t-channel - exchange e*  Not covered: technicolor, single top, leptoquarks, extra dimensions, etc… Moriond EW 2004 Ivo van Vulpen