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From the TeVatron to the LHC: What could lie beyond the SM?

From the TeVatron to the LHC: What could lie beyond the SM?. Monica D’Onofrio IFAE-Barcelona HEP Seminar, University of Oxford, 28 th October 2008. The Standard Model. Matter is made out of fermions: 3 generations of quarks and leptons Forces are carried by Bosons:

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From the TeVatron to the LHC: What could lie beyond the SM?

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  1. From the TeVatron to the LHC: What could lie beyond the SM? Monica D’Onofrio IFAE-Barcelona HEP Seminar, University of Oxford, 28th October 2008

  2. The Standard Model • Matter is made out of fermions: • 3 generations of quarks and leptons • Forces are carried by Bosons: • Electroweak: ,W,Z • Strong: gluons • Remarkably successful description of known phenomena: • predicted the existence of charm, bottom, top quarks, tau neutrino, W and Z bosons. • Very good fit to the experimental • data so far • but ... University of Oxford, 10/28/2008

  3. The missing piece: the Higgs • WOULD THE HIGGS DISCOVERY • COMPLETE OUR UNDERSTANDING OF NATURE ? What is the origin of masses?  Within SM, Higgs field gives mass to Particles (EWK symmetry breaking) SM predicts existence of a new massive neutral particle Not found yet! Theory does not predict its mass LEP limit: mH>114 GeV @ 95% CL Indirect limit from EW data: - Preferred value: mH = 84+34-26 GeV - mH < 154 GeV @ 95% CL with aS (MZ) = 0.1185±0.0026, DaS(5)had=0.02758±0.00035 University of Oxford, 10/28/2008

  4. Beyond SM: the Unknown The Standard Model is theoretically incomplete • Mass hierarchy problem •  radiative correction in Higgs sector • Unification • Dark Matter • Matter-antimatter asymmetry • Many possible new particles and theories • SuperSymmetry • Extra Dimension • New Gauge groups (Z’, W’) • New fermions (e*, t’, b’ …) • … f H DmH2 ~ L2 L = Mpl ? Can show up in direct searches or as subtle deviations in precision measurements University of Oxford, 10/28/2008

  5. Outline • Tevatron and the CDF and D0 experiments • Tevatron sensitivities: achievements understanding the SM • The SM Higgs • Searching for physics beyond SM • Supersymmetry • mSUGRA-inspired searches: • Squark/gluino • Chargino/neutralinos • GMSB-inspired searches • Diphoton+X • Delayed photon analysis • MSSM Higgs • Extra-dimension and new gauge bosons: • Search for high-mass resonances • Perspectives for the LHC University of Oxford, 10/28/2008

  6. _ The Tevatron p p CDF Highest-energy accelerator currently operational D0 Peak luminosity > 3.2 *1032 cm-2 s-1 Integrated luminosity/week  ~ 40-60 pb-1 Delivered: 5.1 fb-1 Acquired: 4.2-4.3 fb-1 (CDF/ DØ) University of Oxford, 10/28/2008

  7. CDF and DØin RunII CDF D0 Took >1 years of collisions to get to stable high efficiency Oct 08 Jan 02 University of Oxford, 10/28/2008

  8. Tevatron Sensitivities • Jet cross section measurements, heavy flavor physics, inclusive W/Z • Precision measurements (Top properties, observation of rare processes...) • New Physics searches, looking for ‘the’ unexpected Both CDF and D0 have a very rich physics program! University of Oxford, 10/28/2008

  9. Knowledge of the SM: QCD and EWK • Z(e+e-)+jets • Clean signature, low background • Test ground for Monte Carlo tools • W Mass and width • MW = 80413±48 MeV • GW = 2032±73MeV • world’s most precise single measurements! Test of Next-to-Leading Order perturbative QCD • inclusive jet cross section • Probing distances ~10-19 m • Constrains gluon PDF at high-x University of Oxford, 10/28/2008

  10. Knowledge of SM: top physics Mtop = 172.4 ± 0.7 (stat) ± 1.0 (syst) GeV/c2 • Top quark discovered at the Tevatron in 1995 • Very extensive program on top physics: • Precision measurements of top mass • Top cross sections, properties… University of Oxford, 10/28/2008

  11. Knowledge of SM: rare processes • DiBoson cross sections D0:s + t = 4.7 ± 1.3 pb CDF: s + t = 2.0-2.7 pb (± 0.7 pbper analysis) Measurements of W/Zg, WW and WZcross sections Consistent with NLO calculation ZZ production  Evidence at CDF Observation at D0!! Consistent with NLO calculation: 1.4 ± 0.1 pb The focus is now to uncover the unknown University of Oxford, 10/28/2008 Evidence of Single top production

  12. Needle in the haystack  Model-inspired searches • Theory driven • Model-dependent optimization of event selection • Set limits on model parameters  Signature-based searches • Signature driven • Optimize selection to reduce backgrounds • Event count; event kinematics Every measurement we make is an attempt to find New Physics When searching for a needle in a haystack, the hay is more important than the needle... Many searches are extensions of SM measurements. University of Oxford, 10/28/2008

  13. The SM Higgs Boson

  14. SM Higgs Production and Decay • Direct production gg→H • Highest Production rate • Largest background • Associated production ZH/WH • Leptonic vector boson decay helps for triggering and signal extraction MH (GeV/c2) • Low Mass (MH<135 GeV/c2) • H→bb mode dominates •  WHlbb, ZHbb , ZHllbb • VBF Production, VHqqbb, H(with • 2jets), H, WH->WWW, ttH • High Mass (135<MH<200 GeV/c2) • H→WW mode dominates University of Oxford, 10/28/2008

  15. Higgs→WW*→ll • Most sensitive channel for high mass Higgs • gg →H → WW* and W(Z)H → W(Z)WW* • Unbalanced transverse energy (MET) from n • 2 leptons: e,,→e, (must haveopposite signs) • Key issue: Maximizing lepton acceptance • Primary backgrounds: Drell-Yan, WW • Higgs is scalar  leptons travel same direction • In t-channel WW, W are polarized along the beam direction • Use Matrix Element and Neural Network methods Results at mH = 165GeV : 95%CL Limits/SM University of Oxford, 10/28/2008

  16. SM Higgs limits CDF/D0 combination: High mass only Exp. 1.2 @ 165, 1.4 @ 170 GeV Obs. 1.0 @ 170 GeV Tevatron exclude at 95% C.L. the production of a SM Higgs boson of 170 GeV Low mass combination difficult due to ~70 channels: Expected sensitivity of CDF/DØ combined: <3.0xSM @ 115GeV A 15 GeV window [162:177] excluded @ 90% CL University of Oxford, 10/28/2008

  17. Searches Beyond SM Supersymmetry

  18. Supersymmetry • New spin-based symmetry relating fermions and bosons: Q|Boson> = Fermion Q|Fermion> = Boson gaugino/higgsino mixing • Minimal SuperSymmetric SM (MSSM): • Mirror spectrum of particles • Enlarged Higgs sector: two doublets with 5 physical states • Naturally solve the • hierarchy problem • Define R-parity = (-1)3(B-L)+2s • R = 1 for SM particles • R = -1 for MSSM partners If conserved, provides Dark Matter Candidate (Lightest Supersymmetric Particle) University of Oxford, 10/28/2008

  19. gravity SUSY breaking (hidden sector) MSSM (visible sector) or Gauge fields, loop effects…. Symmetry breaking No SUSY particles found yet: • SUSY must be broken • More than 100 parameters even in minimal (MSSM) models • Breaking mechanism determines phenomenologyand search strategy at colliders: • Direct searches or subtle deviations in precision measurements mSUGRA, GMSB, …. choose a model  Constrained MSSM models used as benchmark University of Oxford, 10/28/2008

  20. Sparticles mass and cross sections 1. Unified gaugino mass m1/2 2. Unified scalar mass m0 3. Ratio of H1, H2 vevs tanβ 4. Trilinear coupling A0 5. Higgs mass term sgn() • in mSUGRA, new superfields in “hidden” sector • Interact gravitationally with MSSM • 5 parameter at GUT scale T. Plehn, PROSPINO (pb) m (GeV) • Squarks and gluinos are heavy • Sizeable Chargino/neutralino cross sections M(+) ~ M(02) ~ 2M(01) M(g) ~ 3M(+) In R parity conservation scenario, the LSP is the neutralino (c01 ) ~ University of Oxford, 10/28/2008

  21. Inclusive search for squark/gluino mSUGRA: Low tan b scenario (=5 for CDF, = 3 for D0) Assume 5-flavors degenerate q Final state: energetic jets of hadrons and large unbalanced transverse energy(due to presence of c0) ~ q ~ ~ ~ c c 0 0 g q g ~ A0 = 0, m<0 M0 [0,500 GeV/c2] m1/2  [50,200 GeV/c2] q 0 c ~ ~ q q ~ ~ c c 0 0 ~ ~ q q g g q ~ Mq ~ Mg qg final state dominates  3 jets expected ~ q ~ ~ ~ ~ c c 0 0 ~ q g ~ q q q ~ ~ q q 0 0 c Mq > Mg gg final state dominates  4 jets expected ~ ~ ~ ~ ~ ~ c c 0 0 Mq < Mg qq final state dominates  2 jets expected ~ ~ ~ q ~ ~ q q 3 different analyses carried out with different jet multiplicities Final selection based on Missing ET , HT = S (ETjets) and ET jets University of Oxford, 10/28/2008

  22. DiBoson Background rejection Data sample Cleanup • at least one central jet with |h|<1.1 • minimum missing ET of 70 GeV • Reject beam-related backgrounds and cosmics Rejection of SM processes QCD-multijet: ET due to jet energy mismeasurement. W/Z+jets with Wl or Z, DiBoson and tt production: Signaturesvery similar to SUSY Define signal region based on selections that maximize background rejection University of Oxford, 10/28/2008

  23. QCD multijet rejection Missing ET from mis-reconstructed jets  Collinear with one of the leading jets  Apply cuts on Df (missingET-jets) • CDF: remaining QCD-bkg estimatated from Monte Carlo. • Control checks in enhanced QCD-sample • DØ : QCD-bkg extrapolated in data by exponential fit function Df(MET-jets) cut reversed for at least one of the leading jets University of Oxford, 10/28/2008

  24. Z/g* n q n g q g n W q l t b q’ W q q t b Top and Boson+jets rejection Control region • Genuine Missing ET in the event • Suppressed vetoing events with: • jetElectromagnetic fraction > 90%, to reject electrons mis-identified as jets • isolated tracks collinear to missing ETto reject undetected electrons/muons • Modeled using Monte Carlo • Normalized to NLO cross section • Define control regions reversing lepton vetoes  checks of background estimations • Understanding these processes is fundamental Control region University of Oxford, 10/28/2008

  25. DATA vs SM predictions DØ CDF Good agreement between Observed and Expected events Systematic uncertainties dominated by Jet Energy scale University of Oxford, 10/28/2008

  26. Exclusion limits: Mg -Mq andM0-M1/2 plane ~ ~ Similar results for CDF and DØ 95% C.L. Exclusion limit Results can be interpreted as a function of mSUGRA parameters LEP limit improved in the region where 70<M0<300 GeV/c2and 130<M1/2<170 GeV/c2 ~ ~ For Mg=Mq → M > 392GeV/c2 Mg > 280 GeV/c2 in any case ~ University of Oxford, 10/28/2008

  27. Lepton ET Search for chargino/neutralino mSUGRAc02c±1 pair production Signature: three leptons and ET • Small cross sections (~0.1-0.5 pb) • Very low background: • Drell-Yan • Diboson(WW, WZ/*, ZZ/*, W) • Top pair production • QCD-multijets, W+jets (misidentified leptons) e,m,tLept, tHadr • CDF: 5 exclusive channels • combinations of “tight” (t) and “loose” (l) lepton categories • 3-leptons (e,m,tLept) • 2-leptons (e,m,tLept) + iso-track T (tHadr) • Ordered in terms of S/B • DØ: 4 analyses carried out • ee+IsoTrk, mm+IsoTrk, em+IsoTrk, Same-sign mm ttt tlT ttl tll ttT University of Oxford, 10/28/2008

  28. 3 tight leptons selection c02c±1 results 47 Dilepton and trilepton control regions defined to test SM predictions CDF Signal region: Missing ET > 20 GeV + topological cuts Njet=0,1 and ETjet < 80 GeV DØ (4 channels) mSUGRA Benchmark: m0=60 GeV/c2, m1/2=190 GeV/c2, tan=3, A0=0, >0 Data Observed : 3 SM Expected: 4.1  0.7 Good agreement between data and SM prediction  set limit University of Oxford, 10/28/2008

  29. Excluded region in mSUGRA excluded region in mSUGRA m0-m½ space for tan(β)=3, A0=0, μ>0 m0 = 60 GeV/c2 Exclude mc±1< 145 GeV/c2 ~ ~ ~ Small Dm = m(c20 )-m(l), soft leptons from c20 decay  Loss in acceptance, no exclusion University of Oxford, 10/28/2008

  30. Gauge Mediated Symmetry Breaking • SUSY breaking at scale L (10 -100 TeV). Mediated by Gauge Fields (“messengers”) • Gravitino very light (<< MeV) and LSP • Neutralino or slepton can be NLSP • If NLSP is neutralino In Rp conservation scenario:  2 NLSP  2g + MET (+X) in final state Snowmass p8 spectra CDF Run I (taken from N. Ghodbane et al., hep-ph/0201233) University of Oxford, 10/28/2008

  31. gg+Missing ET • Assuming c01 (NLSP) short-lived • Very low SM background • Zgg nngg, Wgg lngg • Understanding of instrumental background challenging: • Mis-measured ET: use multijet data sample • e g misidentification: use W(en)g data 2 photons pTg > 25 GeV, |hg|<1.1 ET> 60 GeV 3 events (SM: 1.60.4) University of Oxford, 10/28/2008

  32. Delayed Photons • c01 life-time undetermined in GMSB  long-lifetime can be in ~ns range • Final state: Delayed photon+ET +jets  ET> 40 GeV, pTg>25 GeV, ETjet > 35 GeV  |h(g)|<1.1, |h(jet)|< 2. Observed 2 events SM Expect.: 1.30.7 M(c01)>101 GeV @ 5 ns tc(g) in [2-10] ns range University of Oxford, 10/28/2008

  33. MSSM Higgs

  34. Neutral MSSM Higgs • In MSSM, two Higgs doublets • Three neutral (h, H, A), two charged (H±) • Properties of the Higgs sector largely determined by mA and tanb • Higher-order effects introduce other SUSY parameters • Large Higgs production cross section at large tanb. Higgs decays: BR(bb) : ~90% Huge QCD background BR(tt) :~10% University of Oxford, 10/28/2008

  35. BSM Higgs:  • CDF and DØ  channel •  pure enough for direct production search • DØ adds associated production search: bb • Key issue: understanding  Id efficiency • Large calibration samples: W for Id optimization and Z for confirmation of Id efficiency mA=140 GeV/c2 • No Evidence for SUSY Higgs • Limits: tan vs mA •  generally sensitive at high tan CDF:  University of Oxford, 10/28/2008

  36. Searches Beyond SM • More ‘Exotic’ models… • - Extra-Dimensions • New Gauge bosons

  37. Search for high mass resonances Example of di-lepton events Transverse plane • Advantage • Sensitive to many BSM scenarios: • Extra-Dimensions • Extended SUSY-GUT groups • (SO(10),E6,E8...leading to additional gauge bosons, Z' and W') • R-parity violating SUSY • and more... • Di-lepton resonances have a strong track record for discovery → J/ψ, Υ, Z • Enlarge the possible final states looking also in dijet,ditop or dibosons! • Construct the pair invariant mass and look for any excesses in the high mass spectrum University of Oxford, 10/28/2008

  38. Extra-Dimensions M2Planck ~ Rn(MD)n+2 ,MD ~ 1 TeV ‘Solves’ the hierarchy problem by postulating that we live in more than 4 dimensions. • Large Extra Dimensions: Arkani-Hamed, Dimopoulos, Dvali (ADD) • Gravity propagate in ndadditional spatial dimensions compactified at radius R • Effective Planck scale: • no narrow resonances, SM particles pair production enriched by exchanged gravitons • Randall-Sundrum model: Only one extra dimensions (wraped) limited by two 4-dimensional brains. • SM particles live in one of the brains. • Graviton can travel in all 5 dimensions, appears as Kaluza-Klein towers • dimensionless coupling (k/MPl) free parameter University of Oxford, 10/28/2008

  39. CDF: Central-Central (|1,2|<1) or Central-Forward (||<2) e+e- pair with ET>25 GeV D0: EM objects pair (e+e- or gg), CC: |1,2|<1.1, CF 1.5<||<2.4 Major Backgrounds: DrellYan QCD (including W+jets) Resonance search performed in mass range 150-1000 GeV/c2 No evidence for narrow resonances  set limits Search for High Mass e+e-/gg Resonance CDF Search for RS Gkk resonance University of Oxford, 10/28/2008

  40. Exclusion limits • CDF (D0) exclude RS graviton with mass below 850 (900) GeV/c2 for k/MPl=0.1 • Can interpret results in term • of several other scenarios • Limits on extended gauge groups theories: SM-like Z’: 966 GeV/c2 • Limits on effective Planck scale in LED: • Expect a cross section enhancement above SM • Use gg, e+e- 1.29 - 2.09 TeV depending on number of ED University of Oxford, 10/28/2008

  41. Di-muon resonances Spin 1 Z’-like limits For the first time beyond one TeV for SM-Z'! Spin 0 (RPV sneutrinos): mass limits up to 810 GeV Spin 2 ( RS Graviton): mass limits up to 921 GeV • Looking for narrow dimuon resonance decaying • Could have spin 0, 1 and 2 • Search in 1/mμμin which detector resolution is ~const:  17% inverse mass resolution at 1 TeV  construct templates for several signal hypothesis, add bkg and compare to data University of Oxford, 10/28/2008

  42. and more! Every final state is currently investigated!!! • dijet resonances • Limits on several models, up to 1.2 TeV! • ditop resonances • limits on massive gluons and leptophobic Z' (Mz' > 760 GeV) • W' in tb(+c.c.) or en final state • world's best limit MW'→ en> 1 TeV • searches for t' or b' • fourth generation quarks not excluded by EWK • interesting tails in t' → Wq • mt' > 311 GeV University of Oxford, 10/28/2008

  43. 8.75 fb-1 7.29 fb-1 today Highest Int. Lum Lowest Int. Lum Final remarks Projection curves FY10 start In case we don’t find new particles @ Tevatron…. ~ 1.8 fb-1 delivered in FY08 FY08 start University of Oxford, 10/28/2008 CDF and D0 have a wide and rich program of searches for SUSY. No evidence yet, but.. expect to collect and analyze up to 8 fb-1 of data in the next years.

  44. 7 TeV + 7 TeV The Future …. now almost present The Large Hadron Collider (LHC) Proton- Proton Collider ATLAS CMS First Event (9/10/2008)! University of Oxford, 10/28/2008

  45. Roadmap to discovery Higgsdiscoverysensitivity (MH=130~500 GeV) Explore SUSY to m ~ TeV Precision SM measurements 1 fb-1 Sensitivity to 1-1.5 TeV resonances → lepton pairs Understand SM backgroundfor SUSY and Higgs Jet energyscalecalibration 100 pb-1 Detector calibration Use SM processes as “standardcandles” 10 pb-1 time 100 pb-1 • High-pT lepton resonances may provide the first signal of New Physics: • Less sensitive to calorimeter performance University of Oxford, 10/28/2008

  46. ATLAS preliminary Jets measurements @ LHC Ze+e- 50 pb-1 Jet energy scale largest source of systematic error initial uncertainty ~ 5-10% Need to reduce error for QCD test LHC (s = 14 TeV) 10 events with Ldt = 20 pb-1 Ldt=1fb-1 Tevatron measure W/Z + jet(s) cross-section γ/Z+jets calibration signal University of Oxford, 10/28/2008

  47. RP-conserving mSUGRA ATLAS preliminary pTjets+ETmiss(GeV) SUSY@LHC Excl The LHC is built to discover SUSY If there, we will find it relatively soon An example: squark-gluino production • But it will take a bit of time: • commissioning phase to understand detector performance and “re-discover” the SM University of Oxford, 10/28/2008

  48. ATLAS preliminary H  ZZ*  4l 30 fb-1 The “golden” channel SM Higgs: a challenge! Required luminosity for 95% C.L. exclusion For low mass of ~120 GeV need to combine many channels with small S/B or low statistics (H  , H→, H ZZ*  4l, H→ WW*→ll ) ATLAS preliminary most promising in the range 150-180 GeV, again with H → WW* →ll  almost excluded at the Tevatron! University of Oxford, 10/28/2008

  49. Conclusions "Whatever" is beyond the Standard Model, these are exciting times for high energy physics! LHC TeVatron? University of Oxford, 10/28/2008

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