# Presentation: 038204

## Other Particle Searches at the Tevatron

- Arnold Pompoš
- The University of Oklahoma
- For the CDF & DØ Collaborations

- Štrbské Pleso

- DIS 2004

- April 14-18

- Slovakia

- 2004

## Outline

- Search for Large Extra Dimensions (LED)
- in Monojet + MET channel
- in ee combined with **γγ**** **channel
- via dedicated search with ee
- in μμ channel
- Search for heavy gauge boson
- in ee channel
- in μμ channel
- Search for excited electrons

- In this talk we report on

- For search for Higgs, SUSY and LQ see
- S. Beauceron, T. Kurca & D. Ryan’s talks

## Tevatron - pp collider

- -

**April 2001**

**Feb 2002**

**first data for analyses**

** ****data for physics**

** ****detector commissioning**

**Jul 2002**

- High data taking efficiency
- in the range 80-90%
- So far analyzed
- around 200 pb-1, which is already 2x the total Run I data.

- ~ 290 pb-1 on tape per experiment

## CDF & DZero Experiments

- Extended spatial e, μ coverage
- New plug calorimeter improves also MET measurement
- Improved MET triggers
- Added triggers to identify  leptons at early stage

- New silicon and fiber tracker
- Solenoid (2 Tesla)
- Upgrade of muon system
- Upgrade of Trigger/DAQ

## New Phenomena Search Strategies

- Both CDF & DZero start searches with

- signature based strategy
- categorize data into bins of various event signatures
- compare bins to SM predictions and search for signs of deviations

- specific models
- show us the signatures of your favorite model
- we tell you if data contains any event with such signature

- and then the searches are tuned for best sensitivity on

## New Phenomena Search Challenges

- Production cross sections very small
- σ(new phenomena) ~ 1 pb
- σ(pp inelastic) ~ 5x1010 pb
- Detectors are great, but not perfect
- particle detection efficiency < 100%
- Often hard to distinguish signal from background
- jet based strategies overwhelmed by SM processes
- we employ lepton based signatures, but the rates are often suppressed

- -

## Large Extra Dimensions

## Motivations for Extra Dimensions

- Newton’s 1/r2 law needs to be tested on submillimeter scales
- Hierarchy puzzle - Why is gravity so weak?
- EWK scale is MEWK~1TeV
- Gravity scale is MPL=1/√GN = 1016 TeV
- Hierarchy solution – Extra Dimensions.
- Gravity is localized (Randal Sundrum) on a different “brane” at d≠0 from the “brane” we live on
- - Gravity propagation to extra D (us) is exponentially damped
- Gravity is not weak! (Arkani-Ahmed, Dimopoulos,Dvali)  It is diluted into many dimensions, 4+n, with n of them compactified to radius R
- M2PL(4 D) = M2+nPL(4+n D)Rn
- - IF MPL(4+n D) ~ MEWK ~ 1TeV then
- if n=1 then R ~ 1013 m (excluded by Newton’s 1/r2 law)
- if n=2 then R~ 10-3 m (WORTH OF TESTING!)

## Strong Gravity ( ADD )

- Compactified n dim. implies massive KK towers GKK of massless graviton G in each extra dim.
- SM lives in 3+1D, GKK live in 4+n D  strength of gravity diluted
- GKK couple to SM matter proportional 1/MPL (very weak coupling)
- Huge number of KK modes sum up and yield to measurable effects

- Monojet+MET event signature

- q

- q

- g

- Gkk

- q

- q

- g

- g

- V

- V

- Gkk

- Gkk

- Gkk

- Gkk

- _

- _

- Possible real graviton emmission

- Enable Graviton Mediated Processes

- Dilepton and diphoton event signature

- g

- g

- g

## LED with Monojet + MET

- Search for Real Graviton Emission

- DØ ∫Ldt = 85 pb-1

- Data Selection:
- MET > 150 GeV,
- Jet1 > 150 GeV
- Jet2 < 50 (reduce ISR, FSR)
- ΔΦJ-MET  > 30o (reduce chance that  MET comes from jet mismeasurement)
- Irreducible Background:
- Z-> **νν** + 1 or 2 jets (60% of total bckg.)

- Limit on Planck Scale Md

- After all selection cuts
- Observe 63, Expect 100 with ~60% uncertainty

- q

- q

- g

- Gkk

- Gkk

- _

- g

- g

- g

- heavy G escapes to extra D
-  large MET
- recoil jet very energetic

**Analysis sensitive to jet **
**energy scale (JES) uncertainty.**

**Data versus SM**** **

- LEP

## LED with ee & γγ - Theory 

-  ηG = F/MS4
-  F is a model dependent dimensionless parameter ~ 1:
-  GRW:       F = 1
-  HLZ:        F = log(Ms2/M2), n =2
-                   F = 2/(n-2), n > 2
-  Hewett:   F = 2 **λ**/π, **λ** = ±1
- Ms is the UV cutoff = MPL(4+n dim)

- LED with **ee** & **γγ** - Theory

- Gravity effect parametrized by G

- ee, **γγ**
- invariant
- mass

- Functions of M & cos*
- determined by theory

- scatter.
- angle

- DØ Search Strategy:
- Combine dielectron and diphoton to diEM signature
- Fit distribution of M vs cos* of Data – SM
- Extract ηG from the fit
- Translate ηG into Ms limit

- Search for enhanced dilepton production

## LED with ee & γγ - Event Selection 

-  Event Selection
- Two fiducial, central-central or central-forward, isolated EM objects
- ET > 25 GeV for both EM objects
- No track selection. Treat dielectron and diphoton samples together

- LED search focuses on very high mass Drell-Yan region (graviton is heavy)
- We are not searching for dilepton mass peaks (will do so in Z’ searches)
- Region of interest is way above the Z mass  very energetic e & **γ**
- Triggers
- high pT single or dielectron triggers
- diphoton triggers

- Unprescaled, >99% efficient
- due to high pT of EM objects

## LED with ee & γγ - Data vs Background 

- Drell-Yan and direct diphoton production estimated from MC
- Instrumental backgrounds estimated from data that fail electron quality cuts
- Normalize backgrounds by fitting to the low di-em mass spectrum, where no LED signal is expected

- LED with **ee** & **γγ** - Data vs Background

- DØ ∫Ldt = 200 pb-1

- Data

- QCD

- SM
- prediction

- Signal
- prediction

- Data vs MC

## LED with ee & γγ - DØ Limits 

- Data agrees with SM prediction
- Extract ηg parameter from fit

- Translate G95% limits to 95% CL l*ower *limits on Planck scale MS,  in TeV, using different formalisms for F

| GRW | HLZ for n =  | Hewett |
| --- | --- | --- |
|  |   2      3      4      5      6      7  | λ = +1/-1 |
| 1.36 | 1.56  1.61  1.36 1.23  1.14  1.08  | 1.22/1.10 |
| 1.43 | 1.67  1.70  1.43 1.29  1.20 1.14  | 1.28/NA |

- DØ RunII

- DØ RunI + Run II

- *NLO k=1.3 scale applied to signal MC

## LED with ee - CDF Limits 

- G95%= 1.17 TeV-4

- Data agrees with SM prediction
- Extract  parameter from M(ee) fit
- Use cos* as a cross check

- Translate G95% limits to 95% CL l*ower *limits on Planck scale MS, in TeV, using different formalisms for F

| GRW | HLZ for n =  | Hewett |
| --- | --- | --- |
|  |   2      3      4      5      6      7  | λ = +1/-1 |
| 1.11 | 1.11  1.17  0.99 0.89  0.83  0.79  | 0.99/0.96 |

- G95%= 1.05 TeV-4

**λ**** = +1**

**λ**** = -1**

- * No NLO k factor applied to signal MC

## LED with μμ - DØ

- LED with μμ - DØ

-  Event selection
- pT > 15 GeV for both muon objects
- Isolated tracks
- M(mumu) > 50 GeV
- Cosmics removed

- Observed  events 3,000 events

- No deviation from SM in data

| GRW | HLZ for n =  | Hewett |
| --- | --- | --- |
|  |   2       3       4      5       6       7  | λ = +1 |
| 0.88 | 0.75  1.05  0.88 0.80  0.74  0.70  | 0.79 |

- Soon see results from 200pb-1

- DØ ∫Ldt = 100 pb-1

## LED with μμ - CDF 

- Data agrees very well with SM predictions
- New LED results are around the corner @ CDF from μμ channel

## LED with KK modes of Z & Photon 

- Model:
- compactified n extra dimensions
- chiral matter lives on 3D
- gauge bosons live in all dimensions -> existence Z & **γ** KK modes
- Task:
- measure the effect of KK modes of Z and **γ** on ee production

- is bilinearly in

- ηC = π2/3*M2PL(4+n dim)

- and depends on dilepton mass and scattering angle

- Search strategy same as in LED:
- extract ηC from fit and translate into a limit on Mc

- Note:
- at high masses the dilepton production is enhanced
- at intermediate masses M(Z)  MC the negative interference causes event deficit.

-  same tools as LED

## LED with KK modes of Z & Photon- Limit 

- same as in diEM search, but
- >1 e must have track
- no electron isolation required

- Observed 14200 events

- No deviation from SM in data

- LED with KK modes of Z & Photon- Limit

- MC>1.12 TeV

- DØ ∫Ldt = 200 pb-1

- Data

- QCD

- SM
- prediction

- Signal
- prediction

- Data vs MC

## Localized Gravity ( RS ) with ee

- Gravity Propagates in Compactified 5th dim. -> Towers of Kaluza-Klein modes of the graviton
- Coupling of GKK to Standard Model is of the order of TeV (determined by parameter k/MPL)
- Graviton mediated ee production searched
- CDF searched its high pT ee & μμ sample

- First direct
- constraints
- on RS

## Localized Gravity ( RS ) with μμ

## Heavy Extra Gauge Boson

## Z’ Search Motivation 

- Z  if  = 0
- Zη  if  = tan-1√(3/5)
- Z  if  = π/2
- ZI  if  = tan-1(-√(3/5))

- Extra U(1) gauge boson is predicted by BSM theories (SO(10),E6)
- SSM : Z ’ couplings to fermions considered identical to the SM Z
- E6 inspired models: E6  SU(3) x SU(2) x U(1)y x U(1) x U(1),   Z ’ = Z sin + Z cos

- We search for leptonic Z’ decays. (Br ~ 4% but very small bckg.)
- Same high pT ee & μμ datasets searched as in LED analysis
- Looking for a mass peak in M(dilepton) distribution, located beyond the Z peak (different from LED searches, where we fit the high mass continuum).

- Z’

## Z’ in ee channel

-          SM Couplings
- 	CDF :               750
- 	DØ:                  780
- 	E6	    ZI    Zχ     Zψ   Zη
-       CDF:      570  610   625  650
-       DØ:        575  640   650  680

- DØ ∫Ldt = 200 pb-1

- Data

- QCD

- SM
- prediction

- Signal
- prediction

- 95% CL limit

- ZI    Zχ     Zψ   Zη

- SM coupling

- Same event selection as for the search for LED in ee channel (KK modes of gauge bosons) .
- Different data interpretation

- Limits (in GeV)

## Z’ in μμ channel – Limits

- Z’ in μμ channel – Limits

- DØ ∫Ldt = 100 pb-1

- DØ result with 200 pb-1 is coming soon.

## Excited Electron

## Electron compositeness? 

- CDF has searched for excited electrons (*e**), whose existence would indicate compositeness of electrons
- At Tevatron, *e**  can be produced via contact interactions or gauge mediated interactions
- We select events with ee in the final state
- Look for resonances in M(e****)
- Region of interest lies beyond the Z mass
- ET(e1)>25 GeV, ET(e2)>25 GeV, ET(****)>25 GeV
- 81 GeV < M(ee) < 101 GeV (veto SM Z)
- SM background: Z**** events

- Contact Interaction

- Gauge Mediated Interaction

- Electron compositeness?

- In CDF ∫Ldt = 200 pb-1 we
- observed 3 events and expected 3 events

- M(e*)/Λ,
- Λ is the compositness scale

- f/Λ,
- f is the coupling to Z

## Excited Electron Limits 

- Contact Interaction Limit

- Gauge Mediated Interaction Limit

- Excited Electron Limits

## Spectacular eeee Event 

- Spectacular eeee Event

- Et(e1)=44 GeV

- Et(e2)=42 GeV

- Et(p1)=46 GeV

- Et(p2)=26 GeV

- MET=13 GeV

- Central tracker

- Calorimeter eta-phi lego plot

- We are not only excluding, we are also measuring 

- ZZ candidate in eeee channel
- σxBr ~ 9x10-4

## Conclusion

## Conclusion 

- Tevatron keeps breaking peak luminosity records and is steadily delivering collisions
- CDF and DØ detectors are recording high quality data
- We searched CDF’s and DØ’s high energy electron, muon and photon samples for signs of new phenomena
- We set world leading limits on parameters of theories which consider the existence of extra dimensions, extra gauge boson or composite electron
- We are still in only a fraction of the expected total luminosity of 8fb-1 (2009) MORE GREAT PHYSICS RESULTS are coming soon and even more in few years .