# Presentation: 529361

## SUSY SEARCHES AT 

**SUSY SEARCHES AT **
**THE TEVATRON**

**HCP (Duke, NC) May 2006**

***Xavier Portell***
***(On behalf of CDF and D0****** ***
***Collaborations)***

## THE TEVATRON

-  s = 1.96 TeV (Run I 1.8TeV )

- p-pbar collider:
-   36x36 bunches at 396 ns crossing time

- Tevatron, CDF and D0 were highly upgraded in Run II.

- Great performance: 1.6 fb-1 delivered
-                             1.3 fb-1 to tape
- Data collecting efficiencies ~ 85%

## WHY DO WE NEED SUSY?

- SUSY:

**Q|Boson> = Fermion**** **

**Q|Fermion> = Boson**** **

- The introduction of SUSY have very interesting implications:
-  Solves the hierarchy problem
-  Unification of forces at GUT scale
-  Provides a Dark Matter candidate
-  ...

- But SUSY also imply new undiscovered particles...

- The SM works very well... but there exist some unresolved problems:

-  Mass hierarchy problem
-  Unification
-  Dark Matter
-  Matter-antimatter asymmetry

## SUSY BREAKING

- Symmetry  Need to be broken  determines phenomenology

- One of the preferred models: mSUGRA

-  New superfields in the “hidden” sector
-  Interact gravitationally with MSSM
-  Soft SUSY breaking
-  Only 5 parameters at SUSY scale

- m0: common scalar mass at GUT
- m1/2: the common gaugino mass at GUT
- tan Ratio of Higgs vaccum expectation values
- A0: Trilinear coupling
- Sign(): Higgs mass term

## R-PARITY

-  *ijk* denote the families involved

** ****Superpartners are pair produced**
** ****Lightest SUSY Particle (LSP)**

- SM particles: Rp=1
- Superpartners: Rp=-1

- Most general SUSY lagrangian  Leptonic and Baryonic number violation in the superpotential

- New quantum number: Rp=(-1)3(B-L)+2s

- When Rp is conserved:

- Dark Matter candidate!

*1        2        1 *

## WHY AT THE TEVATRON?

- Cross Section (pb)

- Cross Section (pb)

- T. Plehn, PROSPINO

-  increase by 3-4 orders of magnitude w.r.t. Tevatron.
-  comparable to Tevatron (and with more background).

**Good prospects for  finding SUSY at the Tevatron!**

**LHC: 14 TeV**

**Tevatron: 1.96 TeV**

- 100 events per fb-1

- T. Plehn, PROSPINO

## RPC

- SQUARKS AND GLUINOS

- CHARGINOS AND NEUTRALINOS

- GMSB CHARGINO/NEUTRALINO

- 3-leptons

-  + MET

- CHARGINO/ NEUTRALINO

- 4-leptons

- b-jets and taus

- STOP

- INDIRECT SEARCHES:
- BS

- RPV

- INDIRECT

- OUTLINE

- MET+jets

## OUTLINE

## SQUARKS AND GLUINOS

- DIRECT SQUARK-GLUINO PRODUCTION:

- DECAY:

- Missing ET

- Missing ET

- Multiple jets

- Studied an mSUGRA scenario with first **4 flavors degenerate** (sbottom/stop not considered)

**Missing E****T**** (MET) + jets**

- Optimized for three cases:
- 2-jets (when Mgl>Msq)
- 3-jets (when Mgl~Msq)
- 4-jets (when Mgl<Msq)

- - Always 3 or more jets
- - Optimization for three different ranges of gluino masses.

- Backgrounds are challenging (specially QCD)

- Strong interaction:  large production expected

## SQUARKS AND GLUINOS

- Distributions after all cuts for CDF and D0 agree with data in all cases.

- 3-jet optimization

- 4-jet optimization

- CDF background contributions after all the cuts.

- Mgl~Msq~330 GeV/c2

- Mgl~240 GeV/c2
- Mgl~507 GeV/c2

##       SQUARKS AND GLUINOS: LIMITS   

-       SQUARKS AND GLUINOS: LIMITS

-   D0: 310 pb-1, A0=0, <0 and tan=3
- CDF: 371 pb-1, A0=0, <0 and tan=5

- Mgl > 387 GeV/c2 (when Mgl~Msq)
- Mgl > 241 GeV/c2 ; Msq > 325 GeV/c2

- CDF: Includes the theoretical uncertainties when calculating the observed limit

- D0: Reduce theoretical cross section by 1more conservative)

##            3rd GENERATION SQUARKS

- SUSY: Predicts left- and right-handed scalar partner eigenstates for each SM fermion
- As 3rd generation is heavier, stop and sbottom could be the lightest SUSY particles.

- Important to have **specific analyses** for them!

- Signatures of 2 or 4 b-jets and MET

**SBOTTOM**

**STOP**

- A Light stop is preferred (consistent with baryogenesis)
*Balazs, Carena, Wagner (hep-ph/0403224)*

- Soft jets        (experimental challenge)

## SBOTTOM

-  At least two jets, one b-tagged.
-  Three different jet/MET thresholds (increasing sbottom mass):
- ET1st > 40-70 GeV 	ET2nd > 15-40 GeV
-             MET > 60-100 GeV

**SELECTION CRITERIA**

**RESULTS**

-  Good agreement data/MC
-  Exclude sbottom masses up to 200 GeV (depending on neutralino mass)

- ET1st > 40 GeV
- ET2nd > 15 GeV
- MET > 60 GeV

## STOP

-  D0: 2 different analyses to improve sensitivity: e, 
-  e analysis: optimized for different m= (Mstop – Msneutrino) values
-  Missing ET > 15 GeV
-  Topological cuts

- The sneutrino usually decays into neutrino and neutralino (MET)

| Optimization | Background | Data |
| --- | --- | --- |
| e (m low) | 23.0  3.1 | 21 |
| e (m high) | 40.7  4.4 | 42 |
|  | 2.9  0.4 | 1 |

- Numbers compatible with SM
- Great improvement with respect to Run I (excluding up to the top mass)

## OUTLINE

## CHARGINOS AND NEUTRALINOS

- Mix to form the mass states

**PRODUCTION**

- In mSUGRA:
- M   ~ M   ~ 2 M

- Always two leptons from

- Always one lepton from

- + Missing ET

- Clean signature and relatively high cross sections
*GOLDEN CHANNEL*

- We have always 2 like-sign leptons (one from each superpartner)

## CHARGINOS AND NEUTRALINOS

- tan determines the lepton flavor composition

- taus dominate

- The third lepton tends to be very soft

- Different trigger paths and cut optimizations for e/and tracks in general

- Low pT zone

- Cuts in lepton PT:
- PT1st~20 GeV/c
- PT2nd~10 GeV/c

## CHARGINOS AND NEUTRALINOS

- Requirements to reduce SM background
- (DY, diboson, conversions...)

-  Minimum pT for the 2 leading leptons
-  Dilepton mass and angle cuts (avoid Z and Drell-Yan)
-  Small jet activity
-  Missing transverse energy significant

**Observed/Expected Events**

**D0**

**CDF**

- All is compatible with SM...

- e+t

- +t

## CHARGINOS AND NEUTRALINOS

- Low tan and slepton mass degenerate

- Results are model dependent (for e.g. with slepton mixing the acceptance is worse and there are no new constraints yet)

- M   > 117 GeV/c2

-  Beyond LEP (in these scenarios)
-  More luminosity is being added
-  Already implementing some improvements...

- M   > 127 GeV/c2

- Different luminosities, different number of analyses and slightly different scenarios

- Low tan and no slepton mixing

## OUTLINE

## GMSB: +MET

- GMSB: +MET

- In Gauge Mediated Supersymmetry Breaking (GMSB) model the neutralino is the NLSP and the gravitino the LSP (~1 keV/c2).

-  is the only dimensioned parameter of the GMSB model.

-  2 photons (ET>25 GeV)
-  MET > 45 GeV
- SM expect: 2.1 events
- Observation: 1 event

- D0 with 760 pb-1:

- New constraints for this process

- Previous D0 result (263 pb-1)

- New D0 result (760 pb-1)

- NLO

- Chargino

- Neutralino

## OUTLINE

## RPV: CHARGINO/NEUTRALINO

-  Onlyfirst term of WRPV is considered (protect proton lifetime)
-  Charge current universality  ||<0.135 GeV
-  RPV vertex: only in the last decay.
-  The decay is inside the detector
-  In general: 
-  CDF: performing analyses only in 121 and 122
-  D0: analysing also 133 (high tanlow m0)

*i,j,k* denote the leptonic families involved.

- 1210  eeee, eee, ee
- 1220  , e, ee

- Only one RPV at a time

**ASSUMPTIONS**

- Low background just for asking 4 leptons or more!

- A pair of      at least 4 leptons and two neutrinos
- Also optimizing for 3 leptons to improve acceptance

## RPV: 4 LEPTONS

| Trilepton Signal Regions |  |  |
| --- | --- | --- |
| Dataset | λ121 : eel | Λ122: l |
| Background | 2.9 ± 0.8 | 1.8 ± 1.0 |
| RpV SUSY | 3.8 ± 0.4 | 4.0 ± 0.4 |
| Data | 5 | 1 |

| ≥ 4 Signal Region |  |
| --- | --- |
| Dataset | Signal |
| Background | 0.008 ± 0.004 |
| RpV SUSY | 1.5 ± 0.3 |
| Data | 0 |

- Probability to see >=5 with 2.9  0.8 is 17%

- Very low background!

| m0=1TeV ; tan=5 |  |  |  | m0=100GeV ; tan=20 |
| --- | --- | --- | --- | --- |
| Dataset | λ121 : eel | 122: l | 133: ee | 133: ee |
| Background | 0.9 ± 0.4 | 0.4 ± 0.1 | 1.3 ± 1.7 | 1.3 ± 1.7 |
| m     (GeV/c2) | 119 | 118 | 86 | 115 |
| m     (GeV/c2) | 231 | 229 | 166 | 217 |

- No event found after cuts

## RPV: STOP

- CHALLENGE:  identification
- Jets and leptons   misidentification
- Used Z for hadronic ID:  Eff ~ 56%

-  2 b-jets
-  1  hadronic (64.8%)
-  1  semi-leptonic (35.2%)

- Expected events: 2.2
- Observed events: 2 (1e + 1)

- New mass limits are obtained with 322 pb-1

**RPV vertex**

**RPV vertex**

## OUTLINE

## INDIRECT SEARCHES: BS

- INDIRECT SEARCHES: BS

- SM: Bs->is heavily suppressed:

- SUSY: BR enhancement by 1-3 orders of magn.

- (Buchalla & Buras, Misiak & Urban)

- (Babu, Kolda: hep-ph/9909476+ many more)

**New CDF result: 780 pb****-1**** **
- Using B+J/ K+ for normalization

- Found 1 event; expected background 0.90.3

- New limits at 95% C.L:
**BR(Bs************) < 1.0·10****-7**** **

- High resolution!
- (M) ~ 0.23 MeV

- R. Dermisek et al. hep-ph/0507233 (2005)

## DISCLAIMER

- Due to time constraints I couldn’t cover all the analyses for both detectors.
- Some of the most interesting analyses, not covered here, are:
-  Stopped gluinos (split SUSY) (350 pb-1)
-  Long lived charginos (AMSB) (380 pb-1)  This topic will be covered in the next talk
-  Resonant slepton production (RPV) (380 pb-1)
-  sneutrinoe (RPV)  (344 pb-1)
- You can find them all at the CDF or D0 webpages:
** ****	**_[http://www-cdf.fnal.gov/physics/exotic/exotic.](http://www-cdf.fnal.gov/physics/exotic/exotic.html)__[html](http://www-cdf.fnal.gov/physics/exotic/exotic.html)_
** ****	**_[http://www-d0.fnal.gov/Run2Physics/WWW/results/np.htm](http://www-d0.fnal.gov/Run2Physics/WWW/results/np.htm)_

## SUMMARY

-  Plenty of SUSY analyses going on at CDF/D0 detectors. They are being improved with the addition of new data.
-  No SUSY particles have been discovered yet but both direct and indirect analyses are constraining the SUSY parameter space.

-  1.6 fb-1 delivered (collected: 1.3 fb-1)
-  Upgrades have been performed during this shutdown
-  This week Tevatron will start again fully operational and 2 fb-1 benchmark is getting closer.

- Tevatron will keep constraining the SUSY parameters until the LHC era... and perhaps a surprise is found!

- Tevatron and detectors are performing very well:

## BACKUPS

## Different 3-Leptons Scenarios

- mSugra the
- BR into taus
- is enhanced
- smaller
- acceptance

## CDF 3-Leptons Analyses

| CHANNEL | LUM | TRIGGER PATH |
| --- | --- | --- |
| ee,e,  | 710 | High pT Single Lepton |
|  + e/ | 750 | High pT Single Lepton |
| ee + e/ | 350 | High pT Single Lepton |
|  + e/ | 310 | Low pT Dilepton |
| ee + track | 610 | Low pT Dilepton |

- No third lepton requirement
- => Higher acceptance

- Use e/mu only
- =>Very small backgrounds

- Sensitive to taus as 3rd lepton
- => Keeps acceptance at high tan

## CDF 3-Leptons Control Regions

**     ****MET**

- MET (GeV)

- Dielectron Invariant Mass(GeV/c2)

- Drell-Yan
- WZ
- ZZ
- ttbar
- Fakes
- -SUSY
-  DATA

**Drell-Yan**
**Dibosons**
**ZZ**
**bbbar**
**- SUSY**
** ****DATA**

- L=607 pb-1

- Dimuon PT(GeV/c)

- N events/2 GeV/c 2

*LS-dilepton analysis has additional Control Regions to test conversion removal*

## CDF 3-electron Event

## 3-LEPTONS: PROJECTIONS

## Bs: PROJECTIONS

- Bs: PROJECTIONS

## SQUARKS/GLUINOS: FUTURE

## SQUARKS AND GLUINOS