1. June_2004E. Gallas - SUSY 20041 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.

2. June_2004E. Gallas - SUSY 20042 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 –

3. June_2004E. Gallas - SUSY 20043 Chicago  Tevatron Main Injector & Recycler DØ CDF  p source TEVATRON Run 2 Upgrade 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 : 2x10 31 cm -2 s -1 Run 2 : 2x10 32 cm -2 s -1

4. June_2004E. Gallas - SUSY 20044 SMT DØ Run 2a Upgrade Solenoid (2T) 4-layer Silicon Vertex and 16-layer Fiber Trackers Muon forward chamber ( |  |<2 ), shielding New preshower, upgrade Calorimeter electronics Upgrade to Trigger and DAQ system

5. June_2004E. Gallas - SUSY 20045 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 !

6. June_2004E. Gallas - SUSY 20046 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 M Pl (apparent 4D Planck Scale): Ms (fundamental Planck Scale) is brought to the TeV range Constraints (cosmology, tabletop expts): –Extra dimensions ‘compactified’ (R C < 1 mm) –require n>1 (g forces at large distances) Collider experiments – only probe for ED for n  3 !

7. June_2004E. Gallas - SUSY 20047 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

8. June_2004E. Gallas - SUSY 20048 Virtual Graviton Exchange The predicted cross section is described by: where  g = F/M S 4 == ( 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(M s 2 /M 2 ), n =2 F = 2/(n-2), n > 2 Hewett F = 2 / , =±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

9. June_2004E. Gallas - SUSY 20049 Search for ED in ee/  channel 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  g =0.6 fakes Bkg

10. June_2004E. Gallas - SUSY 200410 Highest mass Drell-Yan event Invariant mass 475 GeV/c 2, cos θ* = 0.01

11. June_2004E. Gallas - SUSY 200411 di-EM Mass,Cos θ* distributions

12. June_2004E. Gallas - SUSY 200412 Uncertainties: Uncertainties in  G for di-EM sample

13. June_2004E. Gallas - SUSY 200413 LED:  LED in  at DØ - M S > 880 GeV (95% CL) Run 2 Preliminary Luminosity = 100 pb -1 Select events with  2 muons P T > 15 GeV M  > 50 GeV

14. June_2004E. Gallas - SUSY 200414 Summary: Limits on LED M S for 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: η G = F/M 4 S Translate η G limits to 95% CL lower limits on Planck scale M S, 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

15. June_2004E. Gallas - SUSY 200415 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/M C –Predicts Kaluza-Klein states of gauge bosons (  KK, W KK, Z KK, g KK ) produced directly (with sufficient energy) produced indirectly (virtual exchange of KK modes) Lepton pair production cross section depends on –  C =  2 / 3 M C 2, where M C = ‘compactification’ scale of TeV -1 ED This analysis: –look for virtual exchanges of KK excitations of the Z and 

16. June_2004E. Gallas - SUSY 200416 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): M c > 1.12 TeV (95% CL) First search of this type

17. June_2004E. Gallas - SUSY 200417 Z Limits from ee: SM, E 6 Various models propose new neutral gauge bosons –SM couplings –variety of E 6 GUT inspired Dataset 200 pb -1 – same as in ED analysis Limits on Z ’ mass in GeV/c 2 : SM couplings Run I Run II 670 780 E 6 couplings Z I Zχ Zψ Zη 575 640 650 680

18. June_2004E. Gallas - SUSY 200418 Z’:  No evidence: Set limits M(Z’) > 610 GeV Run 2 Preliminary 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

19. June_2004E. Gallas - SUSY 200419 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 TopicPrelim. Run 2 LED : ee and  M S >1.43 TeV (Run 1&2) LED :  M S > 880 GeV * TeV -1 ‘longitudinal’ ED: ee M c > 1.12 TeV Z’ :  M(Z’) > 610 GeV * Z’ : eeM(Z’) > 780 GeV