# Presentation: 502671

## Non-SM Electroweak Symmetry Breaking Searches at the Tevatron

_**Non-SM Electroweak Symmetry Breaking Searches at the Tevatron**_

**Song Ming Wang**
**University of Florida**

***for the CDF Collaboration***

- Outline :
- CDF, Run-I and Run-II
- Review results on CDF searches for Non-SM Electroweak Symmetry Breaking
- Summary

- 19th International Workshop on Weak Interactions & Neutrinos

## CDF in Run-I and Run-II

- In Run-I (1992-1996) CDF used ~100pb-1 data to investigate electroweak symmetry breaking in SM/Non-SM approach
- Applied several important tools for these studies
*e*// identification
- Good calorimetry for jet/MET measurements
- Tagging b,c jets
- Run-II upgrades :
- New data acquisition electronics to cope with higher luminosity
- Extend lepton acceptance
- Larger geometrical acceptance for silicon tracker
- Have collected ~200pb-1 data

## Understanding the Run-II Detector

_**Understanding the Run-II Detector**_

- Have made baseline measurements to demonstrate the level of understanding of our new detector and the new operating enivronment

-  t-tbar candidate,      di-lepton channel (two displaced vertices)

- 

- 

- MET

-  MET+jets
- (good understanding of MET)

- Good understanding of lepton Id

## Non-SM  Electroweak Symmetry Breaking

- Several models created to solve the hierarchy problem, and to explain the origin of EW symmetry breaking

- Extra Dimensions
- Technicolor
- SUSY/MSSM
- Little Higgs

- Review CDF results on searches for the predicted phenomena based on these models

## Searches for Extra Dimensions

- _Extra Dimensions (ED)_
- The large gap between EW and Planck scales is assumed to be due to the geometry of the extra dimensions
- The gap is narrowed by reducing the effective fundamental scale to ~ 1 TeV
- Only Graviton propagates in the ED, other SM particles are trapped in our 3-D brane
- In the compactified ED, the gravity expands into a series of Kaluza-Klein (KK) states

## Large Extra Dimensions (ADD) Model

- (“ADD” => Arkani-Hamed, Dimopoulos,        and Dvali)

- Hierarchy between EW and Planck scales is generated by large volume of extra dimensions

- Gravity propagates freely in ED

-        : Planck scale
-        : radius of ED
-        : new effective fundamental scale
-        : # extra dimensions

*G*

- Our world (3+1dim)

- SM

- (for *M**D*~1TeV, *n*=2 => *R**c*~mm)

_**Search for ADD ED at Tevatron**_

_**Direct G emission :**_

- Our world (3+1dim)

*G*

-  escape into ED, does not return back

- Photon+MET

- jet+MET

_**Virtual G exchange :**_
- contribute to normal SM scattering amplitude
- Enhancement tail in ee//jj spectra
- No resonance in spectra because KK spectrum uniformly spaced => continuous spectrum

- Our world (3+1dim)

*G*

-  escape into ED, and return back

## Searches for Extra Dimensions (ADD) 

_**Direct **__*G*__** Emission (MET+jet)**_

- Search events with large MET and 1 or 2 jets
- MET > 80 GeV
- Et(jet1) > 80 GeV, Et(jet2) > 30 GeV         		        (if 2nd jet present)
- Reduce QCD multi-jets :
-  (MET,jets) > 0.3 rad (MET due to jet energy mis-measurement)
- Reduce W(*l*), Z(*l*+*l*-) :
- Two highest energy jets not purely electromagnetic
- No isolated track
- Remaining background from:
- Z()+jets, W(*l*)+jets (*l* : e,,)
- QCD
- tt, single t, diboson
- #Observe=284,  #Expected=274.1 +- 15.9

## Searches for Extra Dimensions (ADD) 

- No excess in observed events, thus excluded effective Planck scale (MD)

_**Searches for Extra Dimensions (ADD) **_
_**Direct **__*G*__** Emission (MET+jet)**_

***Best limit from the Tevatron on search for direct graviton emission***

|  | MD(TeV) |  |  |
| --- | --- | --- | --- |
| n | CDF (K=1.0) | D0 (K=1.0) | D0 (K=1.34) |
| 2 | 1.00 | 0.89 | 0.99 |
| 4 | 0.77 | 0.68 | 0.73 |
| 6 | 0.71 | 0.63 | 0.65 |

## Randall-Sundrum (RS) Model

_**Randall-Sundrum (RS) Model**_

- Hierarchy between EW and Planck scales is generated by a large curvature of the extra dimensions

*G* is localized in the Planck brane
- The scale of physical phenomena on the TeV brane is

-  *k*: parameter governs the degree of  curvature

- Our world (3+1dim)

- TeV brane

- Planck brane

*G*

_**Search for RS ED at Tevatron**_

- _Virtual __*G*__ exchange :_
- Virtual contribution to scattering processes
- Spectrum of KK states are discrete, and unevenly spaced
- Look for bumps in M*ee *, M**, M*jj*

- =1

- 0.3

- 0.1

- (Pb/GeV)

- 10-2

- 10-6

- 10-4

- 10-8

- 400

- 600

- 800

- 1000

-  d/dM

- Mll (GeV)

- hep-ph/0006041

## Searches for Extra Dimensions (RS) 

_**Searches for Extra Dimensions (RS) **_
_**(Di-lepton)**_

- Using Inclusive high Pt *e*() data sample, select events w/ 2 energetic lepton candidates, Et>25 GeV (Pt>20 GeV)
- Reconstruct invariant mass (Ml+l-) to search for resonance at high mass
- Observe no excess at high mass in *e*+*e*- and +-
- Combine *e* and  results to set limits for Randall-Sundrum model

- M(ee) (GeV)

- 100

- 400

- 0.1

- 0.08

- 0.06

- 0.04

- 400

- 500

- Graviton Mass (GeV)

- 600

- 10-5

- 10-1

- 104

-  Br(pb)

- Graviton Mass (GeV)

- 400

- 600

- 800

- exclude *M**G*<600 GeV (*k/M**Pl*=0.1)

- Sensitive to low *k/M**Pl* and low *M**G*

## Searches for Extra Dimensions (RS) 

_**Searches for Extra Dimensions (RS) **_
_**(Di-jet)**_

- Look for SM deviation in the inclusive jet    sample (75 pb-1)
- Select two highest Et jets in event with |jet|<2
- Observe no resonance in the di-jet mass      spectrum
- Set 95% CL excluded regions
- Randall-Sundrum *G*: 220<M<840 GeV (            =0.3)

- 10-1

- 400

- 800

- 10

- 103

- Graviton Mass (GeV)

-  Br(pb)

- 400

- 800

- Graviton Mass (GeV)

- 0.0

- 0.1

- 0.2

- 0.3

- Sensitive to high *k/M**Pl* and high *M**G*

## Searches for Technicolor

- Technicolor is a dynamic version of the Higgs mechanism, does not contain elementary scalar boson
- Introduce a new strong gauge force (technicolor) and new fermions (technifermions)
- Technicolor acts between technifermions to form bond states
- “Higgs” boson replaced by states of two techniquarks (technipion)

_**Previous CDF searches:**_

- *T* expect to have Higgs boson like coupling to ordinary fermion, => perfer couple to 3rd gen. fermions

- Describe this analysis next

## Searches for Technicolor

_**Searches for Technicolor**_
_**(Lepton+MET+jets)**_

- Search for color singlet T and T in lepton (*e* or ) + MET + jets
- Select isolate *e* (Et>20 GeV) or isolate  (Pt>20 GeV) in central region (||<1)
- MET>20 GeV
- Only 2 jets, Et>15 GeV, ||<2,                  at least one jet tagged as b-jet candidate
- Major background from:
-       ,           ,
- Set 95% CL exclusion region in M(T) vs M(T) plane

- PRL,84,1110

## Run-II Technicolor Sensitivity

_**(Lepton+MET+jets)**_

- Predicted reach for *L*~2fb-1
- Assume the same selections and systematic uncertainty as in Run-I search, but double signal efficiency (due to larger coverage in lepton id, and b-jet tagging)

- hep-ph/0007304

## Searches for Technicolor

_**(Di-jet)**_

_**Di-jet**_
- Use results from the search for resonance at high di-jet mass to set limits for the mass of Color Octet Technirho

- Exclude the mass range: 260<M<640 GeV (Run-II)

- CDF Run-I exclusion: 260<M<480 GeV

## Searches for Non-SM Higgs

_**Results on CDF searches for :**_
- Higgs from SUSY/MSSM
- Double Charged Higgs

## Searches for Charged Higgs (MSSM)

_**Searches for Charged Higgs (MSSM)**_

- If                          , then
- BR(          ) depends on tan(**)

_**Direct Search:**_

- Select events of these signatures:
-  *e*/** + ** + jets + MET
-  ** + jets + MET

-  identified in hadronic decay mode

_**Indirect (Disappearance) Search:**_

- Observe if  the di-lepton and lepton+jets top events (lepton : *e*, **) are suppressed
- For given (t tbar) and {M(H+), tan(**)} , how likely is it to observe N events
- Set exclusion regions in {M(H+), tan(**)}

## Searches for Charged Higgs (MSSM)

_**Searches for Charged Higgs (MSSM)**_

## Searches for Neutral Higgs (MSSM) 

_**Searches for Neutral Higgs (MSSM) **_

- (=h,H,A)

- Look at the channel  with Run-I data (BR~10%)
- Use high Et electron dataset (Pt>18 GeV),  no Tau trigger
- Select events with one hadronic  and one isolated electron candidate
- Observe no excess of events
- Cannot set limit, since search is not sensitive enough due to low acceptance by the trigger

- _Implementation Tau Triggers in Run-II_
- Lepton(Pt>8) + track(Pt>5)
- Di-tau (2 narrow jets)

- MET+tau

## Searches for Neutral Higgs (MSSM)

_**Searches for Neutral Higgs (MSSM)**_

- (=h,H,A)

_**Event Selection:**_
-     4 jets , |jet|<1.5
-     3 jets tagged as b-quark candidate
-  (bb) > 1.9 (bb well separated) ,   to reduce
- Signal acceptance:
- ~0.2% - 0.6%

- Background:
- QCD, ttbar, W/Zbb, W/Zcc

- BR(             ) ~ 90%

- PRL,86,4472

## Searches for Neutral Higgs (MSSM) 

_**Searches for Neutral Higgs (MSSM) **_
_**(Run-II Sensitivity)**_

-  per Expt

-  per Expt

-  +b bbar  : best discovery channel for new Fermilab Run-II luminosity baseline

## Searches for Doubly Charged Higgs 

_**Searches for Doubly Charged Higgs **_

- Doubly charged Higgs are predicted in models that contain Higgs triplets
- Models w/ extension to Higgs sector of SM
- Left-Right symmetric models
- Supersymmetric Left-Right models
- In the Left-Right symmetric models, the Higgs triplets are one of the Higgs multiplets that breaks the symmetry between L and R handed weak interactions at low energy

_**Event Selection:**_

- Select H++/-- pair or singly produced
- Search for 1 pair of same sign *ee*, or , or *e*
-  same sign leptons decay contains low SM backgrounds, provide clean environment for new physics search
- Datasets : inclusive high Pt electron/muon samples (~90 pb-1 for both)

## Searches for Doubly Charged Higgs 

- No excess in observed events
- Example in the same sign e  for Me>80 GeV
- #Obs=1, #Bgd=

_**Exclusion mass region :**_
-  *ee* : no exclusion
-   : MH++/-- < 110 GeV
-  *e* : MH++/-- < 110 GeV

## Summary

- Non-SM Electroweak Symmetry breaking searches have been performed in several channels at CDF
- No evidence of deviation from SM expectation observed so far
- Limits are set for various Non-SM parameters
- CDF Run-II has started successfully. The upgrades will improve the sensitivities to these searches
- Integrated luminosity of data collected at sqrt(s)=1.96 TeV is ~2X that of Run-I
- =>STAY TUNED  for more NEW results in the next winter conferences!!!