# Presentation: 044867

## Searching For Large Extra Dimensions at D

**Extra dimensions**
**Overview of Run 1 results**
**Run 2 expectations**
**Current Run 2 data**
**The diEM channel**
**The di******** channel**
**Summary**

**Ryan J. Hooper (University of Notre Dame)**
***On behalf of the D************ Collaboration***

- Ryan J. Hooper -- DPF, May 24-28, 2002

## String Theory yearns for n=6,7 extra dimensions
Compactified with radius R ~ 10-32m
Astrophysical and table top experiments: 
Ruled out n=1 and put significant 
  	constraints on n=2
Placed limits on R < 0.15mm
“Large” Extra Dimensions (LED)
Arkani-Hamed, Dimopoulos, Dvali (ADD)  hep-th/9809124
Graviton is only particle that propagates in extra dimensions
Effective Planck scale (MS) down to TeV ranges

A solution to the hierarchy problem
Kaluza-Klein modes of the graviton (GKK) can enhance effects at colliders

**Compactified with radius R ~ 10****-32****m**
**Astrophysical and table top experiments: **
**Ruled out n=1 and put significant **
**  ****	****constraints on n=2**
**Placed limits on R < 0.15mm**
**“****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**

- Ryan J. Hooper -- DPF, May 24-28, 2002

## At D we look for direct GKK production
Strong n dependence
1/(MS)n+2
Gluon or vector boson + ET
ET from graviton 
	escaping detection
We look at virtual GKK 
	exchange as well
Weaker n dependence 

 F/MS4  
F = 1  (GRZ)
        = log(MS2/M2) for n=2, 2/(n-2) n>2 (HLZ)
        = 2/;  = ±1  (Hewett)  USED FOR THIS TALK! 
Two lepton or two vector boson final states	

**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****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)**
**        ****= 2********/********; ******** = ±1  (Hewett)  ****USED FOR THIS TALK!**** **
**Two lepton or two vector boson final states****	**

**Extra Dimensions at D******** **

- Ryan J. Hooper -- DPF, May 24-28, 2002

##  D Run 1: Direct GKK Search

**P-pbar ****	****  gluon + G****KK**** **
**Final state jet + E****T**
**Recent 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**

- Ryan J. Hooper -- DPF, May 24-28, 2002

## Final states are dileptons or diphotons
In Run 1 looked at dielectrons + diphotons
For better sensitivity 
	combine e and  to form “diEM”
Invariant mass vs. |cos()|
LEDs at high mass 
	and low |cos()|
Results
127pb-1 of data
ET > 45 GeV
|| < 2.5
ET < 25 GeV

LEP: MS > ~ 0.5-1.2 TeV

**In Run 1 looked at dielectrons + diphotons**
**For better sensitivity **
**	****combine e and ******** to form “diEM”**
**Invariant mass vs. |cos(************)|**
**LEDs at high mass **
**	****and low |cos(************)|**
**Results**
**127pb****-1**** of data**
**E****T**** > 45 GeV**
**|********| < 2.5**
**E****T**** < 25 GeV**
**LEP: M****S**** > ~ 0.5-1.2 TeV**

-  **D******** Run 1: Virtual G****KK**** Search**

***M******S****** > 1.1 TeV for *********
***M******S****** > 1.0 TeV for *********

- Ryan J. Hooper -- DPF, May 24-28, 2002

## 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 MS sensitivities over Run 1
-  Run 2b: 15fb-1 tripling MS sensitivities over Run 1
-  Upgraded D detector
-  Our current Run 2 LED analysis follows the Run 1 virtual GKK analysis previously mentioned
- Also add the dimuon channel

- Ryan J. Hooper -- DPF, May 24-28, 2002

## D Run 2: DiEM Zs

**D******** Run 2: DiEM Zs**

- The Z is a good place to “calibrate” high PT 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**

- Ryan J. Hooper -- DPF, May 24-28, 2002

## D Run 2: LEDs DiEM Channel

**D******** Run 2: LEDs DiEM Channel**

-  We see 2 high mass events

**Monte Carlo**

**Data**

**D******** Run 2 Preliminary**

- Ryan J. Hooper -- DPF, May 24-28, 2002

## 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**

- Ryan J. Hooper -- DPF, May 24-28, 2002

## D Run 2: Di Resonances

**D******** Run 2: Di******** Resonances**

**Once again lets use well known physics to “calibrate”**
**~10pb****-1**** of data**
**Cuts:**** **
**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

- Ryan J. Hooper -- DPF, May 24-28, 2002

## We see a few high mass events

**We see a few high mass events**

**D******** Run 2: LEDs Di******** Channel**

**D******** Run 2 Preliminary**

**Monte Carlo**

**Data**

- Ryan J. Hooper -- DPF, May 24-28, 2002

## Summary

**Extra dimensions can bring the effective Planck scale down to TeV energies **
**D******** in Run 1: **
**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 **
**	****and M****S**** > 1.0 TeV for ********= -1**
**D******** in Run 2:**
**With 2fb****-1****, sensitivity to M****S**** should double vs. Run 1**
**Virtual G****KK**** exchange in diEM and di******
**We currently have J/********, Upsilon and Z resonances**
**See some higher mass events **
**Should have first physics results by ICHEP**

- Ryan J. Hooper -- DPF, May 24-28, 2002