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Searches for Extra Dimensions and Heavy di-lepton Resonances at D0

Searches for Extra Dimensions and Heavy di-lepton Resonances at D0. Elizabeth Gallas Fermi National Accelerator Laboratory Computing Division. 12th International Conference on Supersymmetry and Unification of Fundamental Interactions June 17-23, 2004 Epochal Tsukuba, Tsukuba, Japan.

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Searches for Extra Dimensions and Heavy di-lepton Resonances at D0

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  1. Searches for Extra Dimensions and Heavy di-lepton Resonances at D0 Elizabeth Gallas Fermi National Accelerator Laboratory Computing Division 12th International Conferenceon Supersymmetryand Unification of Fundamental InteractionsJune 17-23, 2004Epochal Tsukuba, Tsukuba, Japan. E. Gallas - SUSY 2004

  2. Outline • 3-Space / Time: • Fermilab Tevatron with Experiment DØ / mid Run 2 • What can Extra Dimensions (ED) do for you ? • Phenomenology (of interest for pp colliders) • 2 particular ED models • Large Extra Dimensions • ADD (Arkani-Hamed, Dimopoulos, Dvali) • TeV-1 ‘longitudinal’ Extra Dimensions • DDG (Dienes, Dudas, Gherghetta) • DØ: A window into ‘Extra Dimensions’ (ED) • DØ: Lepton/Photon Final state searches for : • Large Extra Dimensions (ED) • TeV-1 ‘longitudinal’ Extra Dimensions • Z’ boson • Summary and Conclusions – E. Gallas - SUSY 2004

  3. New Main Injector : 150 GeV Store protons, shoot to target for anti-proton production New recycler : Magnet storage ring for anti-proton Higher energy: 1.96 TeV vs 1.8 TeV Higher cross sections (30 % for the SUSY) Higher antiproton intensity: 6x6  36x36 bunches (3.5 μs  396 ns) Higher luminosity Run 1 : 2x1031 cm-2s-1 Run 2 : 2x1032 cm-2s-1 Chicago  CDF DØ Tevatron p source Main Injector & Recycler TEVATRON Run 2 Upgrade E. Gallas - SUSY 2004

  4. SMT SMT SMT DØ Run 2a Upgrade • Solenoid (2T) • 4-layer Silicon Vertex and 16-layer Fiber Trackers • Muon forward chamber (|h|<2 ), shielding • New preshower, upgrade Calorimeter electronics • Upgrade to Trigger and DAQ system E. Gallas - SUSY 2004

  5. What can Extra Dimensions do for you ? …proposals dating at least back to 1920’s… • Recent renaissance in the theory proposes: • unite all known forces (including gravity) • known particles, electroweak and strong interactions • confined to a ‘brane’ - a hypersurface in the “bulk” of 4+n Dim • gravity appears weak – diluted in extra dimensions. • There is no “desert” • Offers alternative to the “hierarchy problem” • only one important scale in nature -- may be accessible at Tevatron and LHC energies • Lends practical aspects to string theory… • it’s not just a beautiful idea… we can test it ! E. Gallas - SUSY 2004

  6. Large Extra Dimensions (LED)in the ADD Model • ADD (Arkani-Hamed, Dimopoulos, Dvali) model assumes: • n Extra Dimensions of size R • SM particles and interactions are confined to 4D-world (brane) • Gravity propagates in 4+n Dimensional space • Gravity appears weak – diluted in extra dimensions • In this formulation: • where MPl (apparent 4D Planck Scale): • Ms (fundamental Planck Scale) is brought to the TeV range • Constraints (cosmology, tabletop expts): • Extra dimensions ‘compactified’ (RC < 1 mm) • require n>1 (g forces at large distances) Collider experiments – only probe for ED for n3 ! E. Gallas - SUSY 2004

  7. LED Tevatron Search Modes • Direct Searches (graviton escapes the brane) • look for JET recoiling against missing ET (next talk) • Indirect Searches (this talk) • virtual graviton - contributions to l+l-, production E. Gallas - SUSY 2004

  8. Virtual Graviton Exchange • The predicted cross section is described by: where hg = F/MS4 == (in TeV-4) describes strength of gravity in the presence of LED and F is a dimensionless parameter ~ 1 which depends on the formalism (for the effective Lagrangian): GRW: F = 1 HLZ: F = log(Ms2/M2), n =2 F = 2/(n-2), n > 2 Hewett F = 2l/p, l=±1 • Experimentally, the process is defined by the • invariant mass of the di-boson or di-leptons (M) • cosine of the scattering angle, * (|cos *|). • SM term • interference term • direct gravity term E. Gallas - SUSY 2004

  9. Dataset 200 pb-1 Use di-EM objects both ee and  Selections Two EM with Et > 25 GeV with tight quality cuts Fiducial requirements: central EM objects: |eta| < 1.1 central/forward objects: 1.5 < |eta| < 2.4 LED signal MC for hg =0.6 fakes Search for ED in ee/channel Bkg E. Gallas - SUSY 2004

  10. Highest mass Drell-Yan event Invariant mass 475 GeV/c2, cos θ* = 0.01 E. Gallas - SUSY 2004

  11. di-EM Mass,Cos θ* distributions E. Gallas - SUSY 2004

  12. Uncertainties in G for di-EM sample • Uncertainties: E. Gallas - SUSY 2004

  13. - LED in  at DØ LED:  • Luminosity = 100 pb-1 • Select events with • 2 muons • PT> 15 GeV • M > 50 GeV MS > 880 GeV (95% CL) Run 2 Preliminary E. Gallas - SUSY 2004

  14. Summary: Limits on LED MSfor various formalisms F • No evidence for signatures in excess of high-mass dielectron, diphoton or dimuon events over SM expectation, from coupling to Kaluza-Klein gravitons • Fit (di-EM Mass,Cos θ*) distribution • Single parameter for ED effects: ηG = F/M4S • Translate ηG limits to 95% CL lower limits on Planck scale MS , in TeV, using different formalisms for F • DiEM limits - combine Run I & Run 2 – best limits on LED to date • Di limits for Run 2 with more statistics -- in preparation E. Gallas - SUSY 2004

  15. Dedicated ee Search for ‘longitudinal’ Extra Dimensions • Another ED model (TeV-1 “longitudinal” EDs): • proposed by Dienes, Dudas, and Gherghetta (DDG) • Fermions confined to 4D • but SM gauge bosons propagate in TeV-1 ED of size: R = 1/MC • Predicts Kaluza-Klein states of gauge bosons (KK, WKK, ZKK, gKK) • produced directly (with sufficient energy) • produced indirectly (virtual exchange of KK modes) • Lepton pair production cross section depends on • C = 2 / 3 MC2, where MC = ‘compactification’ scale of TeV-1 ED • This analysis: • look for virtual exchanges of KK excitations of the Z and  E. Gallas - SUSY 2004

  16. Jet mis-ID signal C=5TeV-2 SM + fakes Dedicated ee Search for TeV-1 Dimensions (DDG) Predicts strong negative interference effects unlike LED discussed before Use di-EM dataset (200 pb-1) • adding track match • fiducial requirements – same as for LED analysis Find upper limit on C < 2.63 TeV and thereby (lower limit): Mc > 1.12 TeV (95% CL) First search of this type E. Gallas - SUSY 2004

  17. Z Limits from ee: SM, E6 • Various models propose new neutral gauge bosons • SM couplings • variety of E6 GUT inspired • Dataset 200 pb-1 – same as in ED analysis • Limits on Z’ mass in GeV/c2: SM couplings Run I Run II 670 780 E6 couplings ZI Zχ Zψ Zη 575 640 650 680 E. Gallas - SUSY 2004

  18. Z’:  This is a previous result under revision with increased statistics: We used the same dimuon sample as used for LED  search to look for heavy Z-like resonances No evidence: Set limits M(Z’) > 610 GeV Run 2 Preliminary E. Gallas - SUSY 2004

  19. Summary • No signal for new physics observed so far • but some interesting events ! • New Limits from DØ: Extra Dimensions and Z’ * limits under revision with increased statistics • improved limits on additional gauge bosons ! • most sensitive collider search for ED’s to date! • higher efficiency in widest acceptance • di-EM channels using 200 pb-1 integrated luminosity (now 300 pb-1 on tape) • first collider search for TeV-1 ‘longitudinal’ Extra Dimensions E. Gallas - SUSY 2004

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