# Presentation: 749359

##  New 	Phenomena 			 at DØ

** ****New ****	****Phenomena ****	****	****	**** at D****Ø**

- Todd Adams
- Florida State University
- for the
- DØ Collaboration

- Extra dimensions
- Z’
- Leptoquarks
- SUSY

**Lake Louise Winter Institute**

- 2004

## Searches for New Phenomena

- The Standard Model is great, but leaves questions
- New physics necessary to increase our understanding.
- New phenomena are our clearest window into new physics:
- SUSY, leptoquarks, string theory, GUTs, mass,...

- Preliminary results (through summer 2003)

## Large Extra Dimensions

**Why is M****Pl**** >> M****Weak****?**
**Possible solution: **
**large extra dimensions**

- At the Tevatron (pp):
- gravitons appear as contributions to di-lepton/ photon production

**Gravitons are able to propagate in **
**all dimensions**
**Extra dimensions compactified **
**(R****c**** < 1 mm)**
**Current constraints require n****extra****>1**

**4 + n****extra**** **
**dimensions**

- MS = *fundamental *Planck scale

## LED: ee and 

- Search e+e- and  channels for excess events – large invariant mass
- and *cos**

- MS > 1.28 TeV (95% CL)
- Run 2 Preliminary

- Luminosity = 129 pb-1

- Select events with 2 electrons(photons) with ET> 20 GeV

- Example event

## LED: 

- MS > 880 GeV (95% CL)
- Run 2 Preliminary

- Luminosity = 100 pb-1

- Select events with 2 muons with PT> 15 GeV
- and M > 50 GeV

## Z’:  and ee

- No evidence: Set limits
- M(Z’) > 610 GeV
- also in Z’ee
- M(Z’) > 719 GeV
- Run 2 Preliminary

- We can use the same dimuon sample to search for
- heavy Z-like
- resonances

## Leptoquarks

- Carry lepton & baryon number
- Fractional EM charge

- Included in many SM extensions:
- enlarged gauge structure, compositeness, more

- At Tevatron:

- pair production

- Assume: intra-generational coupling only
- (e.g. 1st generation LQ (LQ1)  eq, eq,
-        2nd generation LQ (LQ2)  q, q)

******=*****BF*****(l****±****q)**

**Search for excess of events **
***or***** **
**M(lq) spectrum**

## 1st Generation LQ in eejj

**1****st**** Generation LQ in eejj**

- Require:
-    2  electrons
-        w/ ET(e)>25 GeV
-    2 jets
-        w/ ET(jets)>20 GeV
-    veto Zee
-    ST>375 GeV

- Luminosity = 135 pb-1

- M(LQ1) > 231 GeV
- for =1
- Run 2 Preliminary

- Data: 0 events
- Bkgd: 0.9±0.25

## 1st Generation LQ in ejj

- Require:
-    1 electron w/ ET(e) > 35 GeV
-    2 jets w/ ET(jet) > 25 GeV
-    missing ET > 30 GeV
-    ST12 > 330 GeV
-    MTe > 110 GeV

- M(LQ1) > 156 GeV
- for =0.5
- Run 2 Preliminary

- Luminosity = 121 pb-1

- Data: 3 events  Bkgd: 4.19±1.0 events

## LQ1 Combined Limit

**LQ1 Combined Limit**

## 2nd Generation LQ in jj

**2****nd**** Generation LQ in ********jj**

- M(LQ2) > 186 GeV
- for =1
- Run 2 Preliminary

- Luminosity = 104 pb-1

- Require:
-    2 muons w/ ET()>15 GeV
-    2 jets w/ ET(jet)>25 GeV
-    M()>110 GeV
-    ST>280 GeV

- Data: 1 event
- Bkgd: 1.59±0.49

## GMSB in  + Missing Energy

- Luminosity = 128 pb-1

- Require:
-    2 photons w/ ET()>20 GeV
-    missing ET>35 GeV
-    remove events with likely
-       mis-measured jets or electrons

- Data: 0 events  Bkgd: 1.38±0.30

- Missing ET(GeV)

## Summary

**Stay Tuned!**

- Lots of interesting preliminary results
- Other analyses available on DØ website
- First publications this spring

| Topic | Prelim. Run 2 | Runs I + 2  |
| --- | --- | --- |
| LED : ee and  | MS>1.28 TeV | >1.37 TeV |
| LED :  | MS>880 GeV |  |
| Z’ :  | M(Z’)>610 GeV |  |
| Z’ : ee | M(Z’)>719 GeV |  |
| LQ1 : eejj | M(LQ1)>231 GeV | >253 GeV |
| LQ1 : ejj | M(LQ1)>156 GeV |  |
| LQ2 : jj | M(LQ2)>186 GeV |  |
| GMSB :  + MET | M(  )>80 GeV |  |