# Presentation: 082765

## Searches for New Phenomena at CDF 

- Beate Heinemann, University of Liverpool

- Introduction
- Supersymmetry:
- Higgs
- Squarks and Gluinos
- Charginos and Neutralinos
- Indirect search: Bs
- Signature Based:
- Dilepton and Diphoton
- Diphoton+X
- Summary and Outlook

- MIT, March 6th 2006

## The Standard Model

- Matter is made out of  fermions:
- quarks and leptons
- 3 generations
- Forces are carried by Bosons:
- Electroweak: ****,W,Z
- Strong: gluons
- Higgs boson:
- Gives mass to particles
- Not found yet

*H*

- B. Heinemann

- MIT, 03/06/06

## What is Beyond the SM?

- Many good reasons to believe there is as yet unknown physics beyond the SM
- Many possible new particles/theories:
- Supersymmetry:
- Many flavours
- Extra dimensions (G)
- New gauge groups (Z’, W’,...)
- New fermions (e*, t’, b’, ...)
- Leptoquarks
- Can show up!
- As subtle deviations in precision measurements
- In direct searches for new particles

- B. Heinemann

- MIT, 03/06/06

## There is a Lot Unknown

- The Standard Model
- only accounts for 4% of matter in Universe
- No candidate for Cold Dark Matter (≈25%)
- cannot explain large mass hierarchy in fermion sector:
- >10 orders of magnitude
- does not allow grand unification:
- electroweak and strong interactions do not unify
- has large radiative corrections in Higgs sector
- require fine-tuning of parameters
- Cannot explain matter-antimatter asymmetry?
- Supersymmetry can solve three
- of  these problems

- Hubble Constant

- Matter Density

- SM

- B. Heinemann

- MIT, 03/06/06

## What’s Nice about Susy?

- Unifications of forces possible
- Dark matter candidate exists:
- The lightest neutral gaugino
- Radiative corrections to Higgs acquire SUSY corrections:
- No fine-tuning required
- Changes relationship between mW, mtop and mH:
- Also consistent with precision measurements of MW and mtop

- With SUSY

- B. Heinemann

- MIT, 03/06/06

## CDF and the Tevatron

- B. Heinemann

- MIT, 03/06/06

## Tevatron Run II

- World’s highest energy collider
- Tevatron Accelerator:
- Integrated luminosity >1.5 fb-1 by now:
- CDF data taking efficiency about 83%
- Integrate Ldt=4-8 fb-1 by 2009

|  | √s(TeV) | t(ns) | L(cm-2 s-1) |
| --- | --- | --- | --- |
| Run II | 1.96 | 396 | 1.7x1032 |

- Key parameter: N= • Ldt

**Delivered:  1.6 fb****-1**
**Recorded:  1.3 fb****-1**

**p**

**p**

**_**

- B. Heinemann

- MIT, 03/06/06

## Tevatron Luminosity 

- B. Heinemann

- MIT, 03/06/06

## Measurement of Final State Objects with CDF

**Measurement of Final State Objects with CDF**

- B. Heinemann

- MIT, 03/06/06

## Measurement of Final State Objects with CDF

- Electron ID :
- Coverage : ||<3.6
- ||<2 (w/ trk)
- ID eff. ~ 80-90%

- Photon ID :
- Coverage : ||<2.8
- ID eff. ~ 80%

**Measurement of Final State Objects with CDF**

- B. Heinemann

- MIT, 03/06/06

## Measurement of Final State Objects with CDF

- Muon ID :
- Coverage : ||<1
- ID eff. ~ 90-100%

**Measurement of Final State Objects with CDF**

- B. Heinemann

- MIT, 03/06/06

## Measurement of Final State Objects with CDF

- Tau ID :
- Narrow iso. cluster
- Low # tracks
-  0 identification
- Coverage : ||<1
- ID eff. ~ 46%

**Measurement of Final State Objects with CDF**

- B. Heinemann

- MIT, 03/06/06

## Measurement of Final State Objects with CDF

- Jet ID :
- Cluster of CAL towers
- Coverage : ||<3.6

- Heavy Flavor Jet Tagging :
- Id HF jets via semi-leptonic decay
- Find soft lepton in jets
- Coverage : ||<1
- Id HF jets via finding displaced vertex
- Coverage : ||<1.5

- B. Heinemann

- MIT, 03/06/06

## Future High Energy Colliders

- ILC (>2020?)

- LHC (2007-?)

**p**

**p**

**e****-**

- √s=0.5-1 TeV

- √s=14 TeV

**e****+**

- B. Heinemann

- MIT, 03/06/06

## Supersymmetry

- B. Heinemann

- MIT, 03/06/06

## Supersymmetry

- SM particles have supersymmetric partners:
- Differ by 1/2 unit in spin
**Sfermions** (squarks, selectron, smuon, ...): spin 0
**gauginos** (chargino, neutralino, gluino,...): spin 1/2
- No SUSY particles found as yet:
- SUSY must be broken: breaking mechanism determines phenomenology
- More than 100 parameters even in “minimal” models!

- B. Heinemann

- MIT, 03/06/06

## LSP = lightest neutralino (or sneutrino or stau)
Typical search : NLSP  LSP + (SM particles), LSP undetected :       
Sensitivity: 
LEP: mNLSP ≈ s /2 ≤ 103.5 GeV 
Tevatron: 100- 500 GeV (depends on particle)
Example topologies:

- Typical search : NLSP  LSP + (SM particles), LSP undetected :
- Sensitivity:
- LEP: mNLSP ≈ s /2 ≤ 103.5 GeV
- Tevatron: 100- 500 GeV (depends on particle)
- Example topologies:

-             squarks, gluinos                   chargino+neutralino     GMSB

- How to look for SUSY

- Et

- B. Heinemann

- MIT, 03/06/06

## Sparticle Cross Sections: Tevatron

- 150 events
- produced so
- far (1.5 fb-1)

- Cross Section (pb)

- T. Plehn, PROSPINO

- B. Heinemann

- MIT, 03/06/06

## Sparticle Cross Sections:LHC

- Sparticle Cross Sections:LHC

- 100 events
- with 1 fb-1

- Cross Section (pb)

- T. Plehn, PROSPINO

- B. Heinemann

- MIT, 03/06/06

## Sparticle Cross Sections:LHC

- Sparticle Cross Sections:LHC

- 100 events
- with 1 fb-1

- Cross Section (pb)

- T. Plehn, PROSPINO

- 100 events
- with 1 pb-1

- B. Heinemann

- MIT, 03/06/06

## Minimal Supersymmetric Standard Model:
2 Higgs-Fields: Parameter tan=<Hu>/<Hd>
5 Higgs bosons: h, H, A, H±
Neutral Higgs Boson:
Pseudoscalar A
Scalar H, h
Lightest Higgs (h) very similar to SM
At high tanß:
A is degenerate in mass with either h or H
Decay into either  or bb for mA<300 GeV:
BR(A ) ≈ 10%, BR(A bb) ≈ 90% 
Cross section enhanced with tan2

- 2 Higgs-Fields: Parameter tan=<Hu>/<Hd>
- 5 Higgs bosons: h, H, A, H±
- Neutral Higgs Boson:
- Pseudoscalar A
- Scalar H, h
- Lightest Higgs (h) very similar to SM
- At high tanß:
- A is degenerate in mass with either h or H
- Decay into either  or bb for mA<300 GeV:
- BR(A ) ≈ 10%, BR(A bb) ≈ 90%
- Cross section enhanced with tan2

- Higgs in the MSSM

- C. Balazs, J.L.Diaz-Cruz, H.J.He, T.Tait and C.P. Yuan, PRD 59, 055016 (1999)
- M.Carena, S.Mrenna and C.Wagner, PRD 60, 075010 (1999)
- M.Carena, S.Mrenna and C.Wagner, PRD 62, 055008 (2000)

- B. Heinemann

- MIT, 03/06/06

## Neutral MSSM Higgs

- Production mechanisms:
- bb  A/h/H
- gg  A/h/H
- Experimentally:
- pp  b+X  bbb+X
- pp  +X   +X

- B. Heinemann

- MIT, 03/06/06

## MSSM Higgs: Tau-Selection

- Select Events:
- One  decays to e or 
- One  decays to hadrons
- Require:
- e or  with pT>10 GeV
- Hadronic:
- Narrow Jet with low multiplicity
- 1 or 3 tracks in 10o cone
- No tracks between 10o and 30o:
- Cone size descreasing with increasing energy
- Low 0 multiplicity
- Mass<1.8 GeV
- Kinematic cuts against background:
- W+jets
- Photon+jets
- Dijets

- B. Heinemann

- MIT, 03/06/06

## Acceptance and Background

- Acceptance for Higgs about 1-2%
- Main background:
- Drell-Yan 
- Indistinguishable signature => Separate kinematically
- No full mass reconstruction possible for low Higgs pT:
- Form mass like quantity: mvis=m(,e/,ET)
- Good separation between signal and background

- B. Heinemann

- MIT, 03/06/06

## MSSM Higgs: Mass Distribution

- Data mass distribution agrees with SM expectation:
- M>120 GeV: 8.4±0.9 expected, 11 observed
- Fit mass distribution for Higgs Signal
- Exclude signals at 95% C.L.
- Upper limit on cross section times branching ratio
- We interpret in MSSM benchmark scenarios

- B. Heinemann

- MIT, 03/06/06

## MSSM Higgs: Results

**pp ******** A+X******** ********+X**** (CDF)**
- Sensitivity similar for
- Min. and max. mixing
-  >0 and <0
**pp ******** bA+X********bbb+X (DØ)**
- Best sensitivity for <0
- Lower sensitivity for >0
- Nice complementarity of both modes
- Particularly important if any deviation seen in either mode

- B. Heinemann

- MIT, 03/06/06

## Generic Squarks and Gluinos

- for M(g) ≈ 300 GeV/c2:
- 1000 event produced
- for M(g) ≈ 500 GeV/c2:
- 1 event produced

- Squark and Gluino production:
- jets and
- Golden signature at LHC

- ~

- ~

- B. Heinemann

- MIT, 03/06/06

## Selection:
3 jets with ET>125 GeV, 75 GeV and 25 GeV
Missing ET>165 GeV
HT=∑ jet ET > 350 GeV
Missing ET not along a jet direction:
Avoid jet mismeasurements
Background:
W/Z+jets with Wl or Z
Top
QCD multijets
Mismeasured jet energies lead to missing ET
Observe: 3, Expect: 4.1±1.5

- 3 jets with ET>125 GeV, 75 GeV and 25 GeV
- Missing ET>165 GeV
- HT=∑ jet ET > 350 GeV
- Missing ET not along a jet direction:
- Avoid jet mismeasurements
- Background:
- W/Z+jets with Wl or Z
- Top
- QCD multijets
- Mismeasured jet energies lead to missing ET
- Observe: 3, Expect: 4.1±1.5

- Generic Squarks and Gluinos

- QCD

- ~

- B. Heinemann

- MIT, 03/06/06

## Squark Candidate event

- B. Heinemann

- MIT, 03/06/06

## Impact on SUSY 

- No evidence for excess of events:
- Exclude squarks and gluinos for certain mass values
- D0 excluded gluinos up to 230 GeV
- CDF:
- Interpretation still ongoing
- Likely similar to D0
- Stop and sbottom quarks are excluded from CDF analysis
- 3rd generation is special...

- B. Heinemann

- MIT, 03/06/06

## 3rd generation Squarks

- 3rd generation is special:
- Masses of one can be very low due to large SM mass
- Particularly at high tan
- Direct production or from gluino decays:
- pp bb or tt
- pp gg bbbb or tttt
- Decay of sbottom and stop:
- b b0
- Stop depends on mass:
- Heavy: t t0
- Medium: t b± bW0
- Light: t c0

- ~

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- B. Heinemann

- MIT, 03/06/06

## This analysis:
Gluino rather light: 200-300 GeV
 BR(g->bb)=100% assumed
Spectacular signature:
4 b-quarks + ET
Require b-jets and ET>80 GeV

- Gluino rather light: 200-300 GeV
-  BR(g->bb)=100% assumed
- Spectacular signature:
- 4 b-quarks + ET
- Require b-jets and ET>80 GeV

- Bottom Squarks

- ~

- ~

- Expect:2.6±0.7
- Observe: 4

- Exclude new parameter space in gluino vs. sbottom mass plane

- B. Heinemann

- MIT, 03/06/06

## Light Stop-Quark: Motivation

- If stop quark is light:
- decay only via t->c10
- E.g. consistent with relic density from WMAP data
- Balazs, Carena, Wagner: hep-ph/0403224
- CDM
- m(t)-m(10)≈15-30 GeV/c2
- m(t)<165 GeV/c2
- Search for 2 charm-jets and large Et:
- ET(jet)>35, 25 GeV
- ET>55 GeV

- ~

- ~

- ~

- ~

- ~

- B. Heinemann

- MIT, 03/06/06

## Light Stop-Quark: Result

- Charm jets:
- Use “jet probability” to tag charm:
- Probability of tracks originating from primary vertex
- Improves signal to background ratio:
- Signal Efficiency: 30%
- Background rejection: 92%
- Data consistent with background estimate
- Observed: 11
- Expected: 8.3+2.3-1.7
- Main background:
- Z+ jj -> vvjj
- W+jj -> vjj

- B. Heinemann

- MIT, 03/06/06

## Stop Quark: Result and Future

- Due to slight excess in data:
- No limit set on stop quark mass yet
- Future light stop reach :
- L=1 fb-1:  m(t)<160 GeV/c2
- L=4 fb-1:  m(t)<180 GeV/c2
- LHC:
- Direct production will be tough to trigger
- But gluino decay to stop and top yields striking signature!
- Two W’s, two b-quarks, two c-quarks and missing ET
- If m(g)>m(t)+m(t)

- ~

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- ~

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- ~

- ~

- ~

- B. Heinemann

- MIT, 03/06/06

## Charginos and Neutralinos 

- Charginos and Neutralionos:
- SUSY partners of W, Z, photon, Higgs
- Mixed states of those
- Scenario here:
- Neutralino LSP
- 3 leptons +
- Recent analyses of EWK precision data:
- J. Ellis, S. Heinemeyer, K. Olive, G. Weiglein:
- hep-ph/0411216
- Light SUSY preferred

- ~

- B. Heinemann

- MIT, 03/06/06

## 3 leptons + 

- Many analyses to cover full phase space:
- Low tan:
- 2e+e/
- 2+e/
- High tan:
- 2e+isolated track
- Sensitive to one-prong tau-decay
- Other requirements:
- Significant Et
- Dilepton mass >15 GeV and not within Z mass range
- Less than 2 jets

- Et

- B. Heinemann

- MIT, 03/06/06

## Trileptons: Result

| Analysis | Expected
background | Example SUSY | Data |
| --- | --- | --- | --- |
| Trilepton (+l) | 0.090.03 | 0.40.1 | 0 |
| Trilepton (ee+l) | 0.170.05 | 0.50.1 | 0 |
| Dielectron+track | 0.490.14 | 1.20.1 | 1 |
| Trilepton(+l) | 0.130.03 | 0.12+-0.02 | 0 |

- No hint of SUSY
- Interpretation in progress
- Improve World’s limits further

- Observed event

- B. Heinemann

- MIT, 03/06/06

## GMSB: +Et

- Assume 01 is NLSP:
- Decay to G+
- G light: m ≈ 1 keV
- Inspired by CDF ee+Et
-     event in Run I
- SM exp.: 10-6
- D0 (CDF) Inclusive search:
- 2 photons: Et > 20 (13) GeV
- Et > 40 (45) GeV

|  | Exp. | Obs. | m(+1) |
| --- | --- | --- | --- |
| D0 | 2.5±0.5 | 1 | >192 GeV |
| CDF | 0.3±0.1 | 0 | >168 GeV |

- ~

- ~

- D0+CDF: m(+1)> 209 GeV/c2

- ~

- ~

- B. Heinemann

- MIT, 03/06/06

## Rare Decay: Bs

- SM rate heavily suppressed:
- SUSY rate may be enhanced:
- Related to Dark Matter cross section (in one of 3 cosmologically interesting regions)
- Recently gained a lot of attention in WMAP data SUSY analyses, see e.g.
- B. Allanach, C. Lester: hep/ph-0507383
- J. Ellis et al., hep-ph/0504196
- S. Baek, Y.G.Kim, P. Ko, hep-ph/0406033
- R. Dermisek et al., hep-ph/0507233

- (Buchalla & Buras, Misiak & Urban)

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

- S. Baek, Y.G.Kim, P. Ko, hep-ph/0406033

- B. Heinemann

- MIT, 03/06/06

## Bs vs. Trileptons

- A.Dedes, S. Mrenna, U. Nierste, P. Richardson hep-ph/0507233

- B. Heinemann

- MIT, 03/06/06

## Indirect Search: Bs->

- Preselection:
- Two muons with pT>1.5 GeV/c
- Dimuon vertex displaced from primary
- Identify variables that separate signal from background:
- Decay length: 
- Points towards primary vertex
- Isolated from other tracks
- Construct likelihood of variables:
- Excellent separation
- Cut at likelihood ratio >0.99

- B. Heinemann

- MIT, 03/06/06

## Bs-> :Result and Future

- Result:
- 0 events observed
- Backgrounds:
-  0.81± 0.12 for (CMU-CMU)
-  0.66 ± 0.13 for (CMU-CMX)
- Branching Ratio:
- CDF:
- BR(Bs->)<1.5 x 10-7 at 90%C.L.
- Combined with D0:
- BR(Bs->)<1.2 x 10-7 at 90%C.L.
- Future:
- Probe values of 2x10-8

- B. Heinemann

- MIT, 03/06/06

## Impact of Bs limits: Now 

- S. Baek, Y.G.Kim, P. Ko, hep-ph/0406033

- A.Dedes, S. Mrenna, U. Nierste, P. Richardson hep-ph/0507233

- Starting to constrain MSSM parameter space

- B. Heinemann

- MIT, 03/06/06

## Impact of Bs limits: L=8 fb-1 

- Tevatron will severely constrain parameter space

- S. Baek, Y.G.Kim, P. Ko, hep-ph/0406033

- A.Dedes, S. Mrenna, U. Nierste, P. Richardson hep-ph/0507233

- B. Heinemann

- MIT, 03/06/06

## Impact of Bs limits: LHC

- LHC will probe SM value with about 100 fb-1

- S. Baek, Y.G.Kim, P. Ko, hep-ph/0406033

- A.Dedes, S. Mrenna, U. Nierste, P. Richardson hep-ph/0507233

- B. Heinemann

- MIT, 03/06/06

## Signature Driven Searches

- All SUSY searches cover unique signatures, e.g. I showed direct searches:
- Three lepton and missing ET
- 3 jets and missing ET
- 2 b--jets or c-jets and missing ET
- However, can also search really model independent to make sure we don’t miss anything! Examples:
- Dilepton or diphoton invariant mass
- Diphoton+X

- B. Heinemann

- MIT, 03/06/06

## High Mass Dileptons and Diphotons

- Resonance signature:
- Spin-1: Z’, W’
- Spin-2: Randall-Sundrum (RS) Graviton
- Spin-0: Higgs, Sneutrino

- _Standard Model high mass production:_

- _New physics at high mass:_

- Tail Enhancement:
- Contact Interactions
- Large Extra Dimension (Arkhani-Hamed, Dimopoulos, Dvali)

- B. Heinemann

- MIT, 03/06/06

## Dielectron and Diphoton Mass Spectra

- Dielectron mass spectrum and diphoton mass distributions
- Data agree well with Standard Model spectrum
- No evidence for
- mass peak
- deviation in tail

**ee**

****

- B. Heinemann

- MIT, 03/06/06

## Limits on New Physics

- Mass peak search examples:
- Tail enhancement: contact interaction

| Model | ZSM | Z | Z | Z |
| --- | --- | --- | --- | --- |
| Mass limit (GeV/c2) | 860 | 735 | 725 | 745 |

- Probing New Physics
- - Directly up to 0.9 TeV
- - Indirectly up to 5-8 TeV

- B. Heinemann

- MIT, 03/06/06

## Signature: Diphoton+X

- Search for any objects produced in association with 2 photons
- Electron, muon, tau
- Photon
- Jet
- Missing ET
- Data consistent with background prediction

|  | SM | Data |
| --- | --- | --- |
| +e | 4.50.8 | 2 |
|  | 0.50.1 | 0 |
|  | 1.90.6 | 4 |
| ET | 0.30.1 | 0 |

- =e,,

- B. Heinemann

- MIT, 03/06/06

## Diphoton+X: Invariant Mass

- Kinematic distributions also agree well with background prediction
- Will see what happens with more data!
- Triphoton analysis first physics result with >1 fb-1 of data!

- B. Heinemann

- MIT, 03/06/06

## Summary and Outlook

- CDF and Tevatron running great!
- Often world’s best constraints
- Many unique searches of SUSY, Higgs and new signatures
- Most analyses based on up to 350 pb-1
- Will analyse 1 fb-1 by summer 2006
- Anticipate 4.4-8.6 fb-1 by 2009
- If Tevatron finds no new physics it will provide further important constraints
- And hopefully LHC will then do the job

- more than 1 fb-1!

- B. Heinemann

- MIT, 03/06/06

## Tevatron: Future

- B. Heinemann

- MIT, 03/06/06

## Backup Slides

## SUSY Particles

- gravitino

- B. Heinemann

- MIT, 03/06/06

## Z ́ee Signal Examples

- Angular distribution has different sensitivity for different Z’ models

- B. Heinemann

- MIT, 03/06/06

## Extra Dimensions

- Attempt to solve hierarchy problem by introducing extra dimensions at TeV scale
- ADD-model:
- n ED’s large: 100m-1fm
- M2PL ~ Rn MSn+2 (n=2-7)
- Kaluza-Klein-tower of Gravitons continuum
- Interfere with SM diagrams: =±1 (Hewett)
- Randall Sundrum:
- Gravity propagates in single curved ED
- ED small 1/MPl=10-35 m
- Large spacing between KK-excitations
-  resolve resonances
- Signatures at Tevatron:
- Virtual exchange:
- 2 leptons, photons, W’s, Z’s, etc.
- BR(G->)=2xBR(G->ll)

- KK

- q

- q

- _

- ee, , 

- B. Heinemann

- MIT, 03/06/06

## Randall-Sundrum Graviton

- Analysis:
- 2 photon mass spectrum
- Backgrounds:
- direct diphoton production
- Jets: 0
- Data consistent with background
- Relevant parameters:
- Coupling: k/MPl
- Mass of 1st KK-mode

- B. Heinemann

- MIT, 03/06/06

## Dirac Magnetic Monopole 

- Bends in the ***wrong ***plane* *( high pt)
- Large ionization in scint (>**500 Mips**!)
- Large dE/dx in drift chamber

- mmonopole > **350 GeV/c****2**

**TOF trigger designed specifically for monopole search**

- B. Heinemann

- MIT, 03/06/06

## Neutral Spin-1 Bosons: Z’

- 2 high-PT electrons, muons, taus
- Data agree with BG (Drell-Yan)
- Interpret in Z’ models:
- E6-models:  I
- SM-like couplings (toy model)

- B. Heinemann

- MIT, 03/06/06

## 3-lepton Event

- B. Heinemann

- MIT, 03/06/06