1. Ryan J. Hooper -- DPF, May 24-28, 2002 1 Searching For Large Extra Dimensions at D  Extra dimensionsExtra dimensions Overview of Run 1 resultsOverview of Run 1 results Run 2 expectationsRun 2 expectations Current Run 2 dataCurrent Run 2 data –The diEM channel –The di  channel SummarySummary Ryan J. Hooper (University of Notre Dame) On behalf of the D  Collaboration

2. Ryan J. Hooper -- DPF, May 24-28, 2002 2 String Theory yearns for n=6,7 extra dimensionsString Theory yearns for n=6,7 extra dimensions –Compactified with radius R ~ 10 -32 m –Astrophysical and table top experiments: –Ruled out n=1 and put significant constraints on n=2 constraints on n=2 –Placed limits on R < 0.15mm “Large” Extra Dimensions (LED)“Large” Extra Dimensions (LED) –Arkani-Hamed, Dimopoulos, Dvali (ADD) hep-th/9809124 –Graviton is only particle that propagates in extra dimensions –Effective Planck scale (M S ) down to TeV ranges –A solution to the hierarchy problem –Kaluza-Klein modes of the graviton (G KK ) can enhance effects at colliders Extra Dimensions

3. Ryan J. Hooper -- DPF, May 24-28, 2002 3 At D we look for direct G KK productionAt D  we look for direct G KK production –Strong n dependence 1/(M S ) n+2 –Gluon or vector boson + E T –E T from graviton escaping detection We look at virtual G KKWe look at virtual G KK exchange as well –Weaker n dependence –  F/M S 4 –F = 1 (GRZ) = log(M S 2 /M 2 ) for n=2, 2/(n-2) n>2 (HLZ) = log(M S 2 /M 2 ) for n=2, 2/(n-2) n>2 (HLZ) = 2 /  ; = ±1 (Hewett) USED FOR THIS TALK! = 2 /  ; = ±1 (Hewett) USED FOR THIS TALK! –Two lepton or two vector boson final states Extra Dimensions at D  G KK g q q g g g V V V V

4. Ryan J. Hooper -- DPF, May 24-28, 2002 4 D  Run 1: Direct G KK Search D  Run 1: Direct G KK Search P-pbar gluon + G KKP-pbar gluon + G KK Final state jet + E TFinal state jet + E T Recent monojet resultRecent monojet result –~79pb -1 of Run 1 data –E T > 150 GeV –Leading Jet: E T > 150 GeV –|  –Gives complementary limit to LEP results for n > 4

5. Ryan J. Hooper -- DPF, May 24-28, 2002 5 Final states are dileptons or diphotonsFinal states are dileptons or diphotons In Run 1 looked at dielectrons + diphotonsIn Run 1 looked at dielectrons + diphotons –For better sensitivity combine e and  to form “diEM” Invariant mass vs. |cos(   )|Invariant mass vs. |cos(   )| LEDs at high massLEDs at high mass and low |cos(   )| ResultsResults –127pb -1 of data –E T > 45 GeV –|  | < 2.5 –E T < 25 GeV LEP: M S > ~ 0.5-1.2 TeVLEP: M S > ~ 0.5-1.2 TeV D  Run 1: Virtual G KK Search D  Run 1: Virtual G KK Search M S > 1.1 TeV for  M S > 1.0 TeV for  q,g  e, 

6. Ryan J. Hooper -- DPF, May 24-28, 2002 6 D  Run 2 Expectations Run 1: 0.13fb -1 In Run 2 CM energy 1.96 TeV vs. 1.8 TeV in Run 1 Run 2a: 2fb -1 doubling M S sensitivities over Run 1 Run 2b: 15fb -1 tripling M S sensitivities over Run 1 D  Upgraded D  detector Our current Run 2 LED analysis follows the Run 1 virtual G KK analysis previously mentioned Also add the dimuon channel

7. Ryan J. Hooper -- DPF, May 24-28, 2002 7 D  Run 2: DiEM Zs »The Z is a good place to “calibrate” high P T objects »Using ~10pb -1 of data »We see Z to diEM »Cuts: »Standard D  EM ID »E T > 20 GeV »E T < 30 GeV »|  | < 1.1 or 1.5 < |  | < 2.5 Central + End Cap Central + Central

8. Ryan J. Hooper -- DPF, May 24-28, 2002 8 D  Run 2: LEDs DiEM Channel  We see 2 high mass events Monte Carlo Data D  Run 2 Preliminary

9. Ryan J. Hooper -- DPF, May 24-28, 2002 9 »Highest mass diEM candidate No extra dimensions yet…but let’s not forget the electron’s heavier brother! D  Run 2: DiEM Channel D  Run 2 Preliminary M(diEM) = 376 GeV; cos  * = 0.79; ME T = 8.2 GeV; EM2EM1 E T = 109.7 GeV  = -2.10  = 2.19 No track match E T = 115.4 GeV  = 0.10  = 5.27 No track match

10. Ryan J. Hooper -- DPF, May 24-28, 2002 10 D  Run 2: Di  Resonances »Once again lets use well known physics to “calibrate” »~10pb -1 of data »Cuts: »D  »D  Muon ID »Both muons |  | < 1.6 »P t tracks > 2.5 GeV »For Z plot: Track P t > 15 GeV D  Run 2 Preliminary Green Histograms = Opposite sign muons Blue Histograms = Same sign muons J/  Upsilon Z

11. Ryan J. Hooper -- DPF, May 24-28, 2002 11 We see a few high mass events D  Run 2: LEDs Di  Channel D  Run 2 Preliminary Monte Carlo Data

12. Ryan J. Hooper -- DPF, May 24-28, 2002 12 Summary Extra dimensions can bring the effective Planck scale down to TeV energies Extra dimensions can bring the effective Planck scale down to TeV energies D  in Run 1: D  in Run 1: Direct G KK production results complementary to LEP limits for n > 4 Direct G KK production results complementary to LEP limits for n > 4 Virtual G KK exchange limits of M S > 1.1 TeV for  = +1 Virtual G KK exchange limits of M S > 1.1 TeV for  = +1 and M S > 1.0 TeV for  = -1 and M S > 1.0 TeV for  = -1 D  in Run 2: D  in Run 2: With 2fb -1, sensitivity to M S should double vs. Run 1 With 2fb -1, sensitivity to M S should double vs. Run 1 Virtual G KK exchange in diEM and di  Virtual G KK exchange in diEM and di  We currently have J/ , Upsilon and Z resonances We currently have J/ , Upsilon and Z resonances See some higher mass events See some higher mass events Should have first physics results by ICHEP Should have first physics results by ICHEP