# Presentation: 659146

## Recent results on searches for new Phenomena from DØ

**Recent results on searches for new Phenomena from**** D****Ø**

**SuGRA20**

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003

## outline

**The tools for searches are performing well **
**   ****(e ******** identifications, b tagging...)**
**New Phenomena searches**
**supersymmetry (jets+mE****T****, multilepton, GMSB ********+mE****T****)**
**Exotics (2****nd**** generation leptoquarks)**
**Large Extra Dimensions (dielectron/diphoton, dimuons)**
**Conclusions**

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003

## Luminosity and data sample

**Luminosity**** and data sample**

**   ****   ∫****L.dt ****on tape**** for physics**
**             ****~ 50 pb****-1**** **
**   ****(data september 2002- january 2003)**

** ****Peak ****luminosity**
** ****3.7 **** x 10****31**** cm****-2****s****-1**
**   ****Better than RunI**** **

- week

-  **4-6 pb****-1**

- per week

**~0.5 X Run I**

**Higher production cross sections :  ****1.8->1.96 Tev**** **

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003

##  Certification of the  identification tools  on SM Physics ...and more

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003

## Electron and muon identification

**Electron and muon identification**

**missing E****T**

**electron E****T**

**M****T**

**W p****T**

**Dot : Data**
**Line : MC**

**W ********e******** **

**Z ******

**W characteristics are represented by MC**
**Clear mass peak of Z(ee) and Z(********)**

- DØ RunII Preliminary

**Z ********ee**

- QCD

**   ****: Data**
**   ****: MC**

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003

## Z’ mass limit

**Z’ mass limit**

**Assuming SM-like coupling to femions**** **

**95% CL upper limit **
**    ****M****Z’****>620 Gev**

**Run I M****Z’**** ****> 690 GeV**

**Integrated spectrum **
**(Mee above that mass)**
**Data (dot)**** ****background (line)**

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003

## Event with highest Mee invariant mass

**M****ee************394 GeV****	**

**Event with highest Mee invariant mass**

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003

## ’s are often a significant part of the 
   beyond the Standard Model phenomenology
Trilepton SUSY searches,
third generation leptoquarks,
Higgs searches ...

Need a SM channel to study properties
   of identification (method, efficiency...)

2 searches at DØ are seeing evidence 
   for the decay Z  +-
 e and hadronic  decays
  and hadronic  decays

**   ****beyond the Standard Model phenomenology**
**Trilepton SUSY searches,**
**third generation leptoquarks,**
**Higgs searches ...**
**Need a SM channel to study properties**
**   ****of identification (method, efficiency...)**
** **
**2 searches at DØ are seeing evidence **
**   ****for the decay Z ******** ********+********-**
** ****e and hadronic ******** decays**
** ******** ****and hadronic ******** decays**

****** ****identification **

- Br(         )->e,h

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003

##  Selection :
 isolated e  pT > 15 GeV;
 candidate (jet) pT> 7 GeV
 MT(e) < 60 GeV (suppress W+jets)
 Me < 60 GeV (suppress Z+jets)

Neural net used to tighten ID 
(don’t consider 3-prong decays)

 Use like sign distribution
 as background estimator

**Z ******** ********+********- ********e********h **

** ****Selection :**
** ****isolated e  p****T**** > 15 GeV;**
** ********candidate (jet) p****T****> 7 GeV**
** ****M****T****(e********) < 60 GeV ****(suppress W+jets)**
** ****M****e ************< 60 GeV ****(suppress Z+jets)**
**Neural net used to tighten ********ID **
**(don’t consider 3-prong decays****)**
** ****Use like sign distribution**
** ****as background estimator**

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003

##  Z  +- eh 

- Data:Opp sign 49 evts
- Like sign 35Diff        14  9
- Signal MC normto 50 pb-1:
-              13  4

- Distribution in invariant  mass, calculated
-  using collinear approximation

** ****Z ******** ********+********- ********e********h **

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003

## Z  + - h

***Enhancement at high profile***

**Selection: **
**isolated tight ********, p****T**** >15 GeV**
**jet flagged as a ******
** ****candidate E****T**** > 7GeV**
** ************ ****>2.5**
**-1 track ******

** ******** ****profile= (********2 highest E****T**** towers)/E********T**

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003

## b-tagging

** ******** ****+ jet sample**

**b-tagging**

**b-tagging explores IP significance method**
**Lepton from semileptonic decay of b is very useful**

**Positive IP**

**Negative IP**

** ****Impact Parameter > 0 **
**track crosses jet axis after primary vertex**

- Jet

- Jet

- track

- track

**Interaction point**

**Interaction point**

** ****Impact Parameter < 0 **
**track crosses jet axis before primary **
**   ****vertex**

**Significance = IP/********IP**

- +jet

- jet

- 

- pTRel

- b enhanced

- Resolution

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003

## W+jets production  

**W+jets production  **

- Selection :
**W(******** e********) **
**Isolated**** e : p****T**** > 20 GeV  **
**|h| < 0.8**
**Missing E****T ****> 25 GeV **
**W(************)**
**Isolated  ********: p****T**** > 25 GeV **
**|h| < 1.5**
**missing E****T****> 20 GeV**
**Jets**
**p****T**** > 20 GeV **
**|h| < 2.5**
- MC: PYTHIA
- MC normalized with DATA by area
- Error includes stat. error and
-       dominant syst. error from Jet Energy Scale

**2****nd**** leading jets**

**1****st**** leading jets**

**GeV**

**GeV**

**W(e********)+jets**

- QCD bkg

- QCD bkg

- First step towards study of W(leptons)H( bb) decay process

**35 pb****-1**

**   ****point : Data**
**   ****histo : MC**

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003

## Z+jets production

**Number of jets in Z + jets final states**
**Reconstructed di-jet mass and ********R(=    ********2**** + ********2  ****) between j**

**Di-jet Mass**

******R between di-jets**

**#jets in Z+jets**

- Combined Z(ee)+jets and Z()+jets

- First step towards study of
- Z(leptons)H( bb) decay process

**35 pb****-1**

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003

## Search for New Phenomenain Run II Data

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003

##  and    search : Jets +mET 

**Standard SUGRA**
**Squark - gluino pair production (signal was estimated for sbottom pairs)**
**Cascade decays end **
**- in quarks and/or gluons **
**LSP (neutralino) escapes detection **
**Selection : 2 jets + mET **
**      ****Many instrumental background           “cleaning”**
**Trigger:**
** ****high p****T**** jet > 65 GeV**
**Offline: **
**p****T**** of leading jet > 100 GeV (insures trigger eff)**
**mET calculated adding all calorimeter towers with E>200 MeV**
**Background estimations: **
**PYTHIA-generated and fully simulated samples for physics backgrounds (real ME****T****), **
**fit to low ME****T**** region for QCD background (mismeasured ME****T****)**

**~ 4 pb ****-1**

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003

## Jets +mET

**Jets +mE****T**

**Preliminary results **
**P****T**** leading jet > 100 GeV**

|      # evts

MET bin | QCD  fit | Total
bkg | Data | 95% CL 
 X  (pb) |
| --- | --- | --- | --- | --- |
| > 70 GeV | 17.4  7.9  2.7  | 18.4  7.9  2.7 | 7 | 4.2 |
| > 80 GeV | 8.5  5.0  1.7 | 9.5  5.0  1.7 | 6 | 3.8 |
| > 90 GeV | 4.2  3.0  1.0 | 5.1  3.0  1.0 | 4 | 3.1 |
| > 100 GeV | 2.0  1.7  0.6 | 2.7  1.7  0.6 | 3 | 2.7 |

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003

## Jets +mET

- Views of the highest ET event (180 GeV)

**Jets +mE****T**

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003

## einclusive search  

**e********inclusive search  **

** ****Rich discovery potential : model-independant**

** ****Low SM background :**
**        ****WW, ttbar, Z/************* ->******

** ****Particle ID in D0 improved / RunI**

**Very simple cuts:**
**     ****1 e p****T**** > 15 GeV**
**     ****1 ******** p****T**** >15 GeV**

**Run II**** ****preliminary**

**Backgrounds :**
**- Instrumental from data**
**- Physics from simulation **

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003

## einclusive search  

**e********inclusive search  **

**Run II**** ****preliminary**
**      ****~30 pb****-1**

| mET Cut | DATA | TOT BKG |
| --- | --- | --- |
| >   0 | 13 | 9.6  0.6
         2.6 |
| >   5 | 10 | 7.3 0.6
       2.6 |
| > 10 | 7 | 4.6 0.6
       2.6 |
| > 15 | 6 | 3.0 0.6
       2.6 |
| > 20 | 3 | 2.3 0.6
       2.6 |
| > 25 | 3 | 1.9 0.6
       2.6 |
| > 30 | 2 | 1.6 0.6
       2.6 |
| > 40 | 0 | 1.4 0.6
       2.6 |
| > 45 | 0 | 1.1 0.6
       2.6 |

- ~ 50% Z ****

**100fb**

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003

## Chargino Neutralino in 3 leptons

** ****Signal **

** ****2 points in Minimal SUGRA**** ****m****         ****2m ****        ****90 and 125 GeV**

** ****Selection  eel **

** ****1)  At least 2 electrons (leading e p****T****>15  GeV **
**                              ****2****nd**** e p****T****>10 GeV)**
** ****2)  10<Mee<70 GeV**
** ****3)  M****T****(e,mET)>15 GeV**
** ****4) A third isolated track P****T****>5 GeV********3.0**
** ****5) mET>15 GeV**

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003

## Chargino Neutralino in eel

**Run II**** ****preliminary**

**Chargino Neutralino in eel**

**After cut 1**

**After cut 1 and 2**** **

**QCD= misidentified e’s**

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003

## GMSB 

**Model : “Snowmass ****slope”**** ****(2001 workshop)**
****** ****   ****parameter determining scale of SUSY ****masses**** **
**N**** ****   ****number of messenger****s  ****(-> ****N=1****)**
**M****m**** **** ****m****essenger m****ass scal****e**** ****(-> ****M****m****=2 ********)**
**tan ******** **** ****ratio of v.e.v. of the 2 higgs doublets**** (at EW scale) ****(-> ****tan ******** ****=15)**
**sign(********)**** **** ****sign of higgsino**** mass term ****(-> ******** > 0****)**

** ****LSP is a light (<< 1eV) gravitino**
** ****Phenomenology driven by nature of NLSP**
** “****Bino” NLSP : **

**Signature 2 ******** + mET**

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003

## 
Cuts :
   pT > 20 GeV, track veto
(Jet,mET)<2.5, 
M  80-102 GeV,  pointing 

Background :
True mET
           W,Wj,Zee,tt,
           WW,WZ...
Instrumental
        QCD, 
        Drell-Yan...

**Cuts**** ****:**
**  **** ****pT******** > 20 GeV, track veto**
******(Jet,mE****T****)****<2****.5****, ******
**M******** ******** 80-102 GeV, ******** pointing**** **
**Background**** :**
**True mE****T**
**           ****W********,Wj,Zee,tt,**
**           ****WW,WZ...**
**Instrumental**
**        ****QCD****, **
**        ****Drell-Yan...**

**GMSB :****  ******** ****+ ****m****E****T**

**m E****T**** distribution of 2 ******** events   **
**  ****-  points : data**** **
**  ****-  hist : QCD background    normalized at mE****T****<20 GeV**** **

**DØ Run II Preliminary**

**mE****T**** **

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003

## GMSB :   + mET

**95% CL on ******** : 51TeV**
**Equivalent limit on****m (LSP) = 66 GeV**

**Close to Run I limits!**

**Theory =**
**“****Snowmass**
**  ****Slope”**
**  ****M=2******
**  ****N****5****=1**
**  ****tan********=15**
**  ********>0****  **

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003

## Leptoquarks  

**L****eptoquarks  **

-  Particles coupled  to quarks and fermions
-  Carry both lepton and color quantum numbers
-  Predicted in extended gauge sectors and composite models

- Present search
- Second generation LQ
-  (jj)
- Assuming =1

- Gluon splitting dominant at Tevatron

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003

## 2nd generation LQ in +2jets 

**2nd generation ****L****Q in ********+2jets**** **

** **

** ****Event selection : ** **2 isolated ******** p****T****>15 GeV  opposite sign**
**                              ****2 jets E****T****>20 GeV **
**                              **M  >110
** ****Background : ****Drell-Yan/Z, ttbar, WW**

**Run II**** ****preliminary**** (~30 pb****-1****)**

- MLQ2>157 GeV

**RunI (100 pb****-1****) M****LQ2****>200 GeV**

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003

## Search for Large Extra Dimensions

**Search for ****L****arge Extra Dimensions**

**Studies in the di-EM (e******** and di-******** channels**
**Two variables**
**Invariant mass**
**Cos ********* ( where *********= scattering angle in the rest frame )**

**  ****Assume :**
**       ****- SM particles confined in 3D-brane**
**       ****- gravity propagates in extra-dimensions**
**  ****Look for :**
**         ****excess of high mass dielectron, diphoton events**** over SM **
**         ****expectation, from coupling to ****KK gravitons**

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003

## LED in the ee/ channel 

**L****ED in the ee/******** channel **

**Event selection :**
**2 electromagnetic objects (e/******** E****T****> 25 GeV  **
**mE****T****< 25 GeV **
**Background :**
**Drell-Yan, Direct ******** production ( from MC)**
** ****EM mis-identification (from data****)**

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003

## LED in the channel  

**L****ED in the ********channel  **

**Event selection :**
** ****2 ******** p****T****> 15 GeV,  m********> 40 GeV**

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003

## Fit the distributions in the Minv-cos* plane to determine the
   value of G  (expected to be zero in SM)

Translate 95% CL upper limits on G to 95% CL lower limits on 
   MS, the fundamental Planck scale (in TeV)

**   ****value of ****G****  (expected to be zero in SM)**
**Translate 95% CL upper limits on ****G ****to 95% CL *****lower *****limits on **
**   ****M****S****, the fundamental Planck scale (in TeV)**

-  ->di-EM limit close to Run I
- ->di-MUlimit new channel
-               Both similar to individual LEP limits

**L****ED preliminary results  **

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003

## Conclusions

**D0**** continues to search for many different signatures**
**   ****for new physics.**
**The effects of increased center-of-mass energy **
**   ****and an improved detector can now be seen in**
**   ****improved sensitivity (compared to Run I).**
**We anticipate with excitement the rise of the**
**   ****discovery potential as Run II ‘s dataset accumulates. **

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003

## backup

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003

## DØ upgrade/status

**D****Ø**** upgrade****/status**

**D0 upgrade**
**tracking**
**Silicon vertex**
**Fiber tracker**
**sol****e****noid **
**2 T magnetic field**
**Preshower**
**Muons detector**
**E****lectronics**
**-  Trigger system**

**D0 still commissioning central track        and displaced vertex trigger**

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003

## Z  + - h

**Z ******** ********+ ********-******** ************h**

**Selection: **
**isolated tight ********, p****T**** > 7GeV**
**jet flagged as a **
****** ****candidate E****T**** > 7GeV**
** ************ ****>0.4**

**DØ Run II Preliminary**

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003

- Isolation = Energy of trks,
- excl tau trk, in 0.7 cone
- Profile = E twr(1+2)/Etot

- Plot isolation vs profile:

***Enhancement at high profile***

- Opposite sign data

- Like sign data

**Z ******** ********+********-**Monte Carlo

**Z ******** ********+ ********-******** ************h**

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003

## LED in Monojet +mET

**Search for Real Graviton emission**
**First analysis in jet + mE****T   **
**LEP and CDF : ********mE****T**
**Background **
** ****Z********W, QCD**** **

**eV)**

*****

- RunI
- 94-96 data

- 0.9 TeV

- 0.6 TeV

- Gerard SAJOT for the D0 collaboration

- SuGRA20. 17-21 March 2003