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LHC Prospects on Higgs and physics beyond the Standard Model (SUSY)

LHC Prospects on Higgs and physics beyond the Standard Model (SUSY). Riccardo Ranieri INFN and Università degli Studi di Firenze on behalf of ATLAS and CMS Collaborations DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba (Japan), 20-24 April 2006. ATLAS & CMS at LHC.

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LHC Prospects on Higgs and physics beyond the Standard Model (SUSY)

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  1. LHC Prospects on Higgs and physics beyond the Standard Model (SUSY) Riccardo Ranieri INFN and Università degli Studi di Firenze on behalf of ATLAS and CMS Collaborations DIS2006 XIV International Workshop on Deep Inelastic Scattering Tsukuba (Japan), 20-24 April 2006

  2. ATLAS & CMS at LHC • Detectors optimised for Higgs boson and SUSY searches • very high energy: LHCpp √s=14 TeV • inelastic cross section: σpp=55 mb • interaction rate: 40 MHz • high luminosity: (2x)1033 cm-2s-11034 cm-2s-1 • per year: 20 fb-1100 fb-1 • BIG detectors • CMS: 15 m x 21.5 m • ATLAS: 25 m x 46 m CMS = Compact Muon Solenoid LHC = Large Hadron Collider first collisions in Autumn 2007 ATLAS = A Toroidal LHC ApparatuS LHC Prospects on Higgs and BSM Physics

  3. LHC LHC Prospects on Higgs and BSM Physics

  4. ATLAS LHC Prospects on Higgs and BSM Physics

  5. CMS LHC Prospects on Higgs and BSM Physics

  6. Expected LHC schedule 1st July 2007 LHC closed and set up for beams August 2007 first beam in machine October / November 2007 first collision followed by a short pilot run (~10 pb–1) someday in 2008 first physics run (few fb–1) from 2009 physics run 10/20 fb–1 to 100 fb–1 per year M.Lamont @ TeV4LHC, April 2005http://lhc-commissioning.web.cern.ch/lhc-commissioning/presentations/lamont-comm-tev4lhc.ppt LHC Prospects on Higgs and BSM Physics

  7. Where will we be at LHC startup? Searches at TeVatron up to LHC startup… • year 2007: ~2 fb-1 • mH<125 GeV/c2 covered to exclusion • year 2008: ~4 fb-1 • mH<130 GeV/c2 covered to exclusion • 3σ evidence up to mH=125 GeV/c2 ¿ Higgs boson signal mH=115 GeV/c2 from LEP2 data ? FERMILAB-PUB-03/320-E CERN-EP/2003-011 LHWG Note/2002-01 mH>114.4 GeV/c2 @ 95% CL LHC Prospects on Higgs and BSM Physics

  8. SM Higgs Production at LHC • Associated productionttHand bbH • high-pT lepton, top reconstruction,b-tag - - • Gluon Fusion • the highest cross section • Vector Boson Fusion • two high-pT forward jets • Associated ProductionWHand ZH • oneortwohigh-pT leptons useful for the trigger LHC Prospects on Higgs and BSM Physics

  9. SM Higgs Decays 2mZ LEP excluded “light” Higgs • hadronic and decays are favourite • …but difficult to select • decays into Vector bosons W and Z • “golden” channels • two-photon decays • extremely “clean” but rare and difficult to detect LHC Prospects on Higgs and BSM Physics

  10. Low Mass Higgs: H→ • This decay is very rare (Br≈10-3) • σ(pp→H115)xBr(H→)=76 fb (NLO) • S/B≈1/20 • good resolution mass peak • Electromagnetic Calorimetres crucial for H→: σ(m)/m≈1% needed • motivation for LAr (ATLAS) and PbWO4 (CMS) calorimetres • high granularity • response uniformity • 3 main background processes: • irreducibile: gg/qq→ 81 pb • +jet (with “real” or “fake” second photon) 9x104 pb • hadronic QCD jets (π0 decays) 108pb • ATLAS reach with 10 fb-1 and mH=115 GeV/c2: • Signal Significance: S/√B=2.0 (K-factors not included) CERN/LHCC 96-40 ATLAS TDR 1 CERN/LHCC 96-41 ATLAS TDR 2 CERN/LHCC 97-33 CMS TDR 4 LHC Prospects on Higgs and BSM Physics

  11. - Low Mass Higgs: ttH(→bb) - - • This is the favourite decay • σ(pp→H115)xBr(H→bb)=28 pb • S/B<10-7 • tagging the top quarks helps a lot • t→bW(→μν) • t→bW(→jj) • “crowded” final state • 6 jets (4 of them are b-jets) + additional ISR/FSR jets • 4 b-tagged jets needed to reduce combinatorics • 1 isolated lepton • it’s the key for trigger • optimised analysis • pz from W-mass constraints • likelihood pairing of jets • Final result for likelihood analysis (mH=115 GeV/c2): • 30 fb-1: S/√B=3.4 • 10 fb-1: S/√B=2.0 ν ATL-PHYS-2003-024 LHC Prospects on Higgs and BSM Physics

  12. High mass Higgs: H→ZZ(*)→4μ • The “golden” channel • well defined peaks Z→μ+μ- • mH>2mZ: real Z’s • main backgrounds • reducible: tt, Zbb • μ isolation • Z reconstruction (mZ) • irreducible: ZZ • qq production mechanism dominates  softer muons - - - • Luminosity required for a 5σ discovery: • 10-30 fb-1 if mH>2mZ • 2-3 low luminosity LHC years • up to 100 fb-1 if mH<2mZ • only one reconstructed Z • high luminosity runs CMS AN 2003-005 CMS AN 2003-007 LHC Prospects on Higgs and BSM Physics

  13. ATLAS & CMS Discovery Potential CERN/LHCC 99-15 ATLAS TDR 15 CMS NOTE 2003/033 • After detector calibration and LHC pilot run… • …almost all the “allowed” mass range can be explored during the first year (10 fb-1) • ...after 2 years (≈30 fb-1) 7σ significance over the whole mass spectrum, covered by more than one channel • LEP excess is near… LHC Prospects on Higgs and BSM Physics

  14. MSSM - mSUGRA 4 charged fermions: Charginos: 1,2 ~± 4 neutral fermions: Neutralinos: 1,2.3,4 ~0 5 Higgs bosons: 2 neutral CP-even: h, H 1 neutral CP-odd: A 2 charged: H+,H- mSUGRA 5 parameters: m½, m0, tanβ, A0, sign(μ) LHC Prospects on Higgs and BSM Physics

  15. MSSM Higgs boson masses Higgs Mass [GeV/c2] mH, mA and mH± degenerate for mA>140 GeV/c2 mh increases with mA up to asymptote: mh<130 GeV/c2 Phys.Rev.D66:055004,2002 hep-ph/0205160 • Born level • mh<mZ • mA<mH • mW<mH± • mA=(mH±2-mW2)½ • Loop corrections • depend on top and stop masses, mixing, … • modify previous sequence, important for h when mA/mZ>>1MSSM h behaves as a SMHiggs LHC Prospects on Higgs and BSM Physics

  16. Neutral MSSM Higgs at LHC - • Production: • gg→A/H • pp→A/Hbb • Neutral Higgs mixing (α) modifies couplings to bosons and fermions with respect to the Standard Model • high tanβ • enhanced decays h/H/A→bb,ττ • low mixing α • h→bb,ττsuppressed - - LHC Prospects on Higgs and BSM Physics

  17. H and A searches • A lot of decay channels • “SM like” • h→,bb • H→4ℓ • purely MSSM • A/H→μμ,ττ,bb • H→hh • A→Zh • H±→τν,tb • if decay into SUSY sparticles are allowed • H/A→22 • 2→h1 • Complete coverage of (mA,tanβ) plane with 30 fb-1 • high tanβ-mA region is the more accessible • only h detectable in most of the plane - - ~0 ~ 0 95% CL Limits ~0 ~0 hep-ex/0602042 (LHWG Note 2005-001) LHC Prospects on Higgs and BSM Physics

  18. Enhancement of BR(h/A/H→μ+μ-) for high tanβ Main backgrounds: Drell-Yan Z/g*→μ+μ- tt (both t→bW→bμνμ), Zbb Background suppression b-tagging (suppresses DY) central jet veto (reduces tt, Zbb) ETmiss cut (reduces tt) Three regions (mhmax<135 GeV/c2): Decoupling regime mA>>mhmax h similar to SM, A/H indistinguishable Low mA regime mA<mhmax H similar to SM, h/A degenerate Z peak, high luminosity needed Intense coupling regime mA≈mhmax h/H/A not degenerate in mass indistinguishable (detector resolution) h/H/A→μ+μ- 5σ without systematic uncertainties - - - - - CMS AN 2005-033 LHC Prospects on Higgs and BSM Physics

  19. MSSM Charged Higgs • H± production • if mH±<mt: t→H±b • if mH±>mt: gb→tH± • Decays: • if mH±<mt: H±→τν • if mH±>mt: H±→tb • LEP 95% CL limit: • mH±>78.6 GeV/c2 • decay channels: H±→τν,cs LHWG Note 2001-005 hep-ex/0107031 LHC Prospects on Higgs and BSM Physics

  20. mH±<mt search in tt events lepton from top quark τfrom H±→τντ excess of τ’sin tt events H± mass can not be reconstructed mH±>mt associated production with top gb→tH±(→τντ,tb) background from tt and Wt final states with τ leptons H± searches - CMS NOTE 2000/039 CMS NOTE 2000/045 CMS NOTE 2002/024 CMS AN 2005-067 CMS AN 2006-028 - - LHC Prospects on Higgs and BSM Physics

  21. SUSY LHC discovery reach ~ ~ q (1 TeV/c2) g (1 TeV/c2) 1 fb-1 • 1 fb-1 of data should allow discovery if squark or gluino mass < 1.5 TeV/c2. • ATLAS and CMS potentials similar • Those studies assumed a perfectly known SM physics (only statistical errors on background rate) and ideal detectors (perfectlyaligned, nominalasymptotic performance) • SUSY discovery likely todepend not on statistics buton the understanding of SM background and detector systematics: excess of events LHC Prospects on Higgs and BSM Physics

  22. DISCOVERY SUSY SPECTROSCOPY It is not enough to observe the excess over the Standard Model… This requires a different approach… Fix a set of points in the parameter space Get information on the spectrum (end-points) Reconstruct sparticles LHC Prospects on Higgs and BSM Physics

  23. The golden decay p p ~ c01 ~ ~ ~ q ~ c02 l g q q l l The measurement of the missing transverse energy ETmiss is the key point • The neutralino leptonic decay is the starting point for reconstruction of the sparticle masses CERN/LHCC 99-14 ATLAS TDR 14 CERN/LHCC 99-15 ATLAS TDR 15 hep-ph/0007009 m0=100 GeV/c2 m½=300 GeV/c2 A0=-300 GeV sign(μ)=+ ∫L=5 fb-1 tanβ=6.0 e+e- + m+m- ∫L=30 fb-1 tanβ=2.1 Edge accuracy with 30 fb-1: 0.5% Mll (GeV/c2) LHC Prospects on Higgs and BSM Physics

  24. Lepton scale: LHC goal: 0.1% material budget, alignment, magnetic field Jet energy scale: LHC goal: 1% FSR, jet cone Reconstruction can be done with only 1-10 fb-1 Statistical uncertainties <<1% with 300 fb-1 Main uncertainty: energy scale and LSP mass Sparticle reconstruction p b b p 300 fb-1 LHC Prospects on Higgs and BSM Physics

  25. The earliest discovery? Z′ (new gauge boson) ? … ? AH, ZH (Little Higgs) ? G(KK) (ADD) ? (1)/Z(1) (TeV-1 Extra Dimensions) ? G(1) (Randall-Sundrum) ? • A new resonance decays into two leptons… LHC Prospects on Higgs and BSM Physics

  26. Conclusion • LHC has potential for Higgs boson(s) and SUSY particles discovery already in the first year (months?) of operation • 1 LHC day at 1033 cm-2s-1≡ 10 years at previous machines BUT • At the beginning a lot of time (whole first year?) will be needed to understand the detectors, reach the desired performance, optimize physics selection and precisely measure SM backgrounds HOWEVER • The ATLAS and CMS detectors are designed for new physics searches, no surprise that they can cover most of the spectrum of Higgs and sparticle masses within 1 year of start of physics collisions LHC Prospects on Higgs and BSM Physics

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