# Presentation: 692166

## Search for Large ExtraDimensions at the Tevatron

- Kevin Burkett, Harvard University
- on behalf of the CDF and D0 collaborations
- Outline:
- Tevatron in Run I – CDF, D0 detectors
- Signatures of Extra Dimensions
- Results of Searches for Graviton Exchange
- Results of Searches for Graviton Emission
- First Look at Run II

- Kevin Burkett, Planck02 - May 25, 2002

## Tevatron Performance in Run I

- proton-antiproton collider
- s = 1.8 TeV

- Luminosity

- Run I: Oct 92 – Feb 96
- Integrated Luminosity  ~120 pb-1/expt.

- Kevin Burkett, Planck02 - May 25, 2002

## CDF and D0 Detectorsin Run I

- Kevin Burkett, Planck02 - May 25, 2002

## Collider Signatures for Large Extra Dimensions

- n Extra Dimensions are compactified
- SM world constrained to 4D brane, gravity can propagate in bulk
- (4+n)D Planck scale related to 4D Planck scale
-                          MPl2 ~ Rn MS2+n
- Signatures:
- - Direct Graviton Emission
- - Virtual Graviton Exchange

- Collider Searches for LED have focused on models of Arkani-Hamed, Dimopoulos, and Dvali (ADD)

- Kevin Burkett, Planck02 - May 25, 2002

## Collider Signatures for Large Extra Dimensions

- Direct Graviton Emission

- Virtual Graviton Exchange

-  Jets + Missing ET
-  Photon + Missing ET

-  Dileptons
-  Diphotons

- Kevin Burkett, Planck02 - May 25, 2002

## Virtual Graviton Searches

- Pair production in virtual graviton exchange
- Interference between SM and Graviton exchange

- SMINTKK  whereF/Ms4

- Three terms in cross section: SM, interference, graviton

- 1                      (GRW)
- log(MS2/M) n=2  (HLZ)
- (2/n-2)      n>2  (HLZ)
- 2/(Hewett)

- Definitions of F :

- Kevin Burkett, Planck02 - May 25, 2002

## D0 Search in Diphotons and Dielectrons

- Combine Diphotons and Dielectrons by dropping track
- requirements on electrons
- Require 2 EM Objects
- ET > 45 GeV
- |d|<1.1 or   1.5< |d|<2.5
- ET < 25 GeV
- All Run I data: 127 pb-1
- 1282 events in final sample
- Main backgrounds: Drell-Yan and 
- Use both invariant mass and |cos| in fit for 

- Kevin Burkett, Planck02 - May 25, 2002

## D0 Search in Di-photons and Di-electrons 

- Using M(EM-EM) and |cos| separately

- Kevin Burkett, Planck02 - May 25, 2002

## D0 Search in Diphotons and Dielectrons

- Combine
- M(EM-EM)
- and |cos|
- in final fit

- Kevin Burkett, Planck02 - May 25, 2002

## D0 Search in Diphotons and Dielectrons

- Limits (95%CL):
-    MS > 1.2 TeV (GRW)
-         > 1.1 TeV (Hewett =+1)
-         > 1.0 TeV (Hewett =-1)
-    HLZ:

| n | MS(TeV) |
| --- | --- |
| 2 | 1.4 |
| 3 | 1.4 |
| 4 | 1.2 |
| 5 | 1.1 |
| 6 | 1.0 |
| 7 | 1.0 |

- - Data agrees well with SM
- - No excess of events at large M(EM-EM) and small |cos| where signal would dominate
- - Set limits on MS

- Kevin Burkett, Planck02 - May 25, 2002

## CDF Search in Diphotons 

- Cross-Section for

- Event Selection:
- ET22 GeV, ||<1
- Use central-central (CC) and central-plug (CP)

|  | CC | CP |
| --- | --- | --- |
| Data | 287 | 192 |
| SM | 9663 | 7631 |
| Fakes | 18463 | 13228 |

- Results:

- Ms Limits (95%CL):
- 899 GeV (=-1 Hewett)
- 797 GeV (=+1 Hewett)

- Kevin Burkett, Planck02 - May 25, 2002

## CDF Search in Dielectrons 

- Similar to Diphoton Analysis

- Perform Simultaneous Fit for:
- 	nSM(CC), nSM(CP), nBKG(CP), 

|  | Expected | Fit |
| --- | --- | --- |
| nSM(CC) | 3463223 | 332756 |
| nSM(CP) | 3883292 | 368763 |
| nBKG(CP) | 22471 | 15124 |

- Ms Limits (with K=1.3):
- 826 GeV (=-1 Hewett)
- 808 GeV (=+1 Hewett)

- Data: 3319(CC), 3825(CP) evts

- Results:

- Kevin Burkett, Planck02 - May 25, 2002

## CDF Search in Dielectrons 

- Central-Central Dielectrons

- Central-Plug Dielectrons

- Kevin Burkett, Planck02 - May 25, 2002

## CDF Search in  Diphotons and Dielectrons

|  | Dilepton | Dilepton+
Diphoton |
| --- | --- | --- |
| GRW | 925 | 1051 |
| Hewett =+1 | 808 | 853 |
| Hewett =-1 | 826 | 939 |
| n=3 (HLZ) | 1100 | 1250 |
| n=4 (HLZ) | 925 | 1051 |
| n=5 (HLZ) | 836 | 950 |
| n=6 (HLZ) | 778 | 884 |
| n=7 (HLZ) | 735 | 836 |

- Combine MS Limits(GeV) from Dileptons and Diphotons

- Kevin Burkett, Planck02 - May 25, 2002

## CDF and D0 Results for Diphotons and Dielectrons

| Model | CDF | D0 |
| --- | --- | --- |
| GRW | 1051 | 1200 |
| Hewett =+1 | 853 | 1100 |
| Hewett =-1 | 939 | 1000 |
| n=3 (HLZ) | 1250 | 1400 |
| n=4 (HLZ) | 1051 | 1200 |
| n=5 (HLZ) | 950 | 1100 |
| n=6 (HLZ) | 884 | 1000 |
| n=7 (HLZ) | 836 | 1000 |

- Run I MS Lower Limits from Graviton Exchange (GeV)

- Dileptons(OPAL)   MS> 1180, 1170 (=+1,-1)
- Diphotons(Comb.) MS>    970,  940 (=+1,-1)

- LEP:

- Kevin Burkett, Planck02 - May 25, 2002

## Graviton Emission Searches

- Graviton produced along with photon or jet

- Additional jets possible from ISR, FSR
- Signature is jets or photon + ET

- Kevin Burkett, Planck02 - May 25, 2002

## D0 Search in Jets+ET

- Event Selection:
- ET(jet1)>150 GeV, ||<1
- ET(jet2)<50 GeV
- ET > 150 GeV
- |(Jet2,ET)| > 15o to reduce QCD background
- Reject events with isolated muons
- Reject cosmic ray events

| Background | Expected # Evt |
| --- | --- |
| Z+jets | 21.0  5.1 |
| We+jets |   3.1  0.7 |
| W+jets |   0.8  0.3 |
| W+jets |   5.3  2.3 |
| QCD/Cosmics |   7.8  7.1 |
| Total | 38.0  9.6 |

- Kevin Burkett, Planck02 - May 25, 2002

## D0 Search in Jets+ET

- N(data) = 38
- N(bkgd) = 38.0 **** 9.6
- Expected Signal
- (n=2, MS=1TeV)
- N(signal)= 19.5 **** 3.9

- D0 Search in Jets+ET

- Kevin Burkett, Planck02 - May 25, 2002

## D0 Search in Jets+ET

| n | MS(GeV)
  K=1.0 | MS(GeV)
  K=1.34 |
| --- | --- | --- |
| 2 | 886 | 987 |
| 3 | 734 | 797 |
| 4 | 683 | 728 |
| 5 | 639 | 661 |
| 6 | 626 | 646 |
| 7 | 617 | 629 |

- Limits on MS(GeV) at 95%CL

- D0 Search in Jets+ET

- Kevin Burkett, Planck02 - May 25, 2002

## CDF Search in +ET

- Look for graviton emission
- Event Selection:
- ET >55 GeV, ||<1.1
- ET > 45 GeV
- Remove cosmic ray events
- No jets w/ ET>15 GeV
- No tracks w/ pT>5 GeV/c

- 11 events found in 87 pb-1 (RunIb)

- Kevin Burkett, Planck02 - May 25, 2002

## CDF Search in +ET

-      Cosmics                6.3 ****** **2.0** **
-      Z3.2 ****** **1.0
-      We0.9 ****** **0.1
-      Prompt 0.4 ****** **0.1
-      W0.3 ****** **0.1
-    Total                    11.0 ****** **2.2
- Observed in Data      11

- Limits (95% CL):
-       n=4          MS>549 GeV** **
-       n=6          MS>581 GeV** **
-       n=8          MS>602 GeV** **

- CDF Search in +ET

- Kevin Burkett, Planck02 - May 25, 2002

## CDF Search in +ET

- For low values of MS cross-section in MC is higher for increasing values of n
- At low MS, limits higher for larger values of n

- CDF Search in +ET

- Kevin Burkett, Planck02 - May 25, 2002

## CDF Search in Jets+ET

- No limits yet
- Preliminary result expected
- by end of summer
- Expected sensitivity for
- MS ~900 GeV (n=2)

- Kevin Burkett, Planck02 - May 25, 2002

## Can We Determine n from ET?

- Graviton mass distribution peaks higher for n=6
- No difference seen in ET
- 2 competing effects
- Heavier gravitons in n=6 case will have larger ET
- Heavier gravitons produced closer to threshold due to falling PDFs

- MD=1TeV

- Kevin Burkett, Planck02 - May 25, 2002

## Tevatron, Detector Upgrades for Run II

- Tevatron Upgrades for Run II
- s = 1.8 TeV 1.96 TeV
- Crossing rate 3.5 sec  396 nsec
- Expect ~200 pb-1 by end of year

- D0
- New 2T solenoid
- New silicon, fiber tracker
- Silicon to ||=3
- Retain calorimeter, but faster readout

- CDF
- New silicon, drift chamber, TOF
- New secondary vertex trigger
- New scintillating tile plug cal.
- Extends to ||=3.6

- Detector Upgrades for Run II

- Kevin Burkett, Planck02 - May 25, 2002

## First Look at Run II Data

- Zee Candidates from CDF and D0

- Kevin Burkett, Planck02 - May 25, 2002

## D0 Expected Run II MS Sensitivity (TeV)

| n |  Early Run II (300 pb-1) |
| --- | --- |
| 2 | 1.40 |
| 3 | 1.15 |
| 4 | 1.00 |
| 5 | 0.90 |

- Jets+ET Search

|  | Run IIa 
(2 fb-1) | Run IIb 
(20 fb-1) |
| --- | --- | --- |
| Dileptons | 1.3-1.9 | 1.7-2.7 |
| Diphotons | 1.5-2.4 | 2.0-3.4 |
| Combined | 1.5-2.5 | 2.1-3.5 |

- Dilepton, Diphoton Search

- Kevin Burkett, Planck02 - May 25, 2002

## First D0 Plots in Virtual Graviton Search in RunII

- Follows Run I analysis
- Both ee and 
- Use mass, cos
- ET(EM) > 25 GeV

- First data agrees qualitatively with background prediction
- Highest mass candidate consistent with background topology
- No limits yet

- Kevin Burkett, Planck02 - May 25, 2002

## Conclusion

- Results from Run I analyses nearly complete
- All should be out by end of summer
- No evidence yet for Large Extra Dimensions
- Run II has begun at the Tevatron
- Upgraded D0 and CDF detectors are operating well
- Expect 100-200 pb-1 of data by end of the year
- First Run II results at next winter conferences

- Kevin Burkett, Planck02 - May 25, 2002