# Presentation: 580389

##        	Status of Searches for  at CDF

- Tracey Berry
- Liverpool University

-  Introduction to & Status of the Tevatron and CDF
-  Extra Dimensional Models and their Signatures
-  Search channels, Search Strategy
-  Comparison of Background Expectation to Data
-  Preliminary Results & Status of Searches
-  Summary and Outlook

- Extra Dimensions

- * searches presented by A. Anastassov

## CDF @ Tevatron pp Collider 

**CDF @ Tevatron**** p****p**** Collider **

***Highest energy collider operating in the world!***

- and ability to set improved limits on new physics

- D0

**p**

**p**

- CDF

- Run I  (1992-1996)
- √s  1.8 TeV, 110 pb-1
- Run II  (2001-2009)
- √s  1.96 TeV

- Ldelivered ~400/pb

- Run II  (2001-2009)
- √s  1.96 TeV
- Physics Analyses use ~ 200/pb collected between 03/02 and 09/03
- diphoton search 300/pb

**p**

## Tevatron Perfomance

- 02

- 05

- 04

- 03

- 100

- The complex is running extremely well
- Ahead of luminosity projections for FY05
- Regularly get shots >100e30 and upwards of 130e30

- Numbers are an average of CDF and D0

## CDF Detector

_*CDF detector is essentially new, commissioned and now taking physics-quality data!*_

- Improved sensitivity for leptons and photons

**New for Run 2**
- Tracking System
- Silicon Vertex detector (SVX II)
- Intermediate silicon layers (ISL)
- Central Outer tracker (COT)
- Scintillating tile forward calorimeter
- Intermediate muon detectors
- Time-Of-Flight system
- Front-end electronics
- Trigger System (pipelined)
- DAQ system

**Retained from Run 1**
- Solenoidal magnet (1.4 Tesla)
- Central Calorimeters
- Central Muon Detectors

## 1 fb-1 Delivered at CDF !

- 90%

- 80%

## Extra dimensional solutions to the hierarchy problem  (MEW << MPlanck?) 

- Many large extra dimensions (n=2-7)
- gravity freely propagates in the ED

- Taking the compact space to be very large

- Curvature of the extra dimension

- 1 highly curved extra dimension
- gravity localised in the ED

- Scale of physical phenomena on the TeV-brane is specified by the exponential warp factor:
-            = Mple-kRc
-      ~ TeV if kRc ~11-12.

- Planck	        TeV brane

- for n  2, Rc < 1 mm

- Vn = 2Rcn

- MPl(4+n) ~ 1 TeV

- MPl2 = VnMPl(4+n)(2+n)

-  requires Rc ~ 10(30/n –19) m

*To solve hierarchy*
*        **choose*

- Torus

- ADD

- RS

## Experimental Signatures for

**Experimental Signatures for**

- ADD

**Graviton exchange**

- Signature: ET + jet(s), ET + V

- _New Parameters  _(Hewett formalism)
- Ms & , dimensionless parameter, 1
- (MD = MPl(4+n))

- Run I

- Gupta et. al. hep-ph/9904234

- =+1

- Cross section depends on the number of ED

-      virtual contribution to the scattering processes
-     Signature: deviations in cross sections  and asymmetries of SM processes
-       e.g.	qq-bar  l+l-,  
-       	Or new processes e.g. gg  l+l-
-       Cross section independent of the number
- 	 of ED in Hewett formalism

**Direct Graviton**** ****emission** in association with a vector-boson

## Experimental Signature for          Model

- RS

- 6

- 700 GeV KK Graviton at the Tevatron
- k/MPl = 1,0.7,0.5,0.3,0.2,0.1 from
- top to bottom

-    Mll (GeV)

- RS model

- Dilepton channel

-               400  600  800 1000

- Mll (GeV)

- 10-2
- 10-4
- 10–6
- 10-8

- 10-2
- 10-4
- 10-6
- 10-8
- 10-10

- Tevatron 700 GeV KK graviton

- d/dM (pb/GeV)

- Couplings of each individual KK excitation are determined by the scale, = Mple-kRc ~ TeV  masses mn = kxne-krc (J1(xn)=0)

** ****Virtual Graviton exchange**

- Davoudiasl, Hewett, Rizzo hep-ph0006041

-      1000     3000     5000

- 1
- 0.5
- 0.1
- 0.05
- 0.01

- 1
- 0.7
- 0.5
- 0.3
- 0.2
- 0.1

- KK excitations can be excited individually on resonance

- Signature: an excess of events in the dilepton or dijet channel.

- 1500 GeV GKK                          and subsequent tower states

- K/MPl

-  LHC

## CDF Search Channels

* * Completed
-   On their way!
-   Imminent  -        this summer!

_**Search Strategy**_
- Aim to make generic signature-based searches (e.g. ee channel)
- Perform general searches comparing data to expectation
- So we can interpret data according to many new models
- 	(e.g. G: RS and ADD, Z': SM, E6; RPV  )!

| Channel |  |  |  |
| --- | --- | --- | --- |
|  | Run I    | Run II    | Run II     |
| Emission |  |  |  |
|  + ET 	 | 	 |  |  |
| jet + ET 	 | 	 |  () |  |
| Virtual Graviton Exchange |  |  |  |
| ee | 	 | 	 |   & 	 |
|  |  | 	 | 	 |
| ee &  |  | 	 | 	 |
|  | 	 |  	 |   &  	 |
|  & ee | 	 |  |  |
| jet-jet |  |  |   &   |
| ZZ |  |  |  () |

## Universal Extra Dimensions

**n=1 KK mode Tree level**

- degenerated mass spectrum at tree level

**n=1 KK mode one-loop corrected**

- Radiative Corrections

- shifted mass spectrum

- UED

- All SM particles propagate in the extra dimensions
- T. Appelquist, H.-C. Cheng and B. A. Dobrescu,  Phys. Rev. D64, 035002 (2001)

- _MUED Free__ Parameters  _
- {**R, ********, m****h**} **           **R-1= 500 GeV, R =20, mh=120 GeV

- H.-C. Cheng, K.T. Matchev and M. Schmaltz, Phys. Rev. D66, 036005 (2002)

**Notes:**
Lamda is the cut off scale at which all boundary terms are negligible.

## Experimental Signature for        

- Experimental Signature for

- g1  Q1/q1 + Q/q
- B(g1  Q1Q)  B(g1  q1q)  0.5
- q1  q + 1
**Signature:** **jets + missing energy (ME****T****)**
- Q1  W1/Z1 + Q
- W1/Z1  L1 + L
- L1  L + 1
- B(Q1  W1±Q)  65%,
- B(Q1  Z1Q)  33%

- UED

**MUED**: H.-C. Cheng, K. T.Matchev and M. Schmaltz, Phys. Rev. D66, 056006 (2002)

- g1         : KK gluon
- Q1 /L1  : SU(2)-doublet KK quark/lepton
- q1 /l1    : SU(2)-singlet KK quark/lepton
- W1/Z1  : KK W/Z                    1 : LKP
- Q,q,L,l,: ordinary (SM) particles

**Signature:** **multileptons + ME****T**** + jets**

**Notes:**
compactified S1  only zero mode observable at low energy

## CDF UED Search Channels

**CDF UED Search Channels**

**Search Channels**
**W****1****Z****1**** (3 lepton final state) and Z****1****Z****1**** (4 lepton final state)**
**Signature**
**multi-lepton + missing energy + jets**

- 4/9

- 1/9

- Q1 Decay Channels

**Notes:**
Tau’s don’t contribute very much to our search because their detection efficiency is much smaller compared with muons and electrons.
Explain why we don’t search W1W1 (too many dilepton backgrounds)

## G Emission: +Et

**G Emission: ********+E****t**

**Limits**
- n=4  MD > 0.55 TeV
- n=6  MD > 0.58 TeV
- n=8  MD > 0.60 TeV

**Search Selection    **
-  - One  with ET > 55 GeV and ||<1
-  - ET > 45 GeV
-  - No jets with ET > 15 GeV
-  - No tracks with pT > 5 GeV

**Results**
- Expected background: 11.0  2.3
- Observed: 	        11

| Cosmic ray muons | 6.3  2.0 |
| --- | --- |
| Z0+ | 3.2  1.0 |
| W e (““) | 0.9  0.1 |
| Prompt diphotons | 0.4  0.1 |
| W ()  | 0.3  0.1 |

**Main backgrounds**

- 87 pb-1 Run I

## G Emission: jet(s)+Et

- Dashed lines for  from Pythia
- Solid lines prediction from Giudice, Rattazi and Wells (hep-ph9811291)

-  falls as 1/MDn+2 for all subprocesses

- qq-bar  gG is larger for larger values of n, relative to the other sub-processes,
- since (gggG) and (qggG)
- depend on (m2/s)4
- Whereas (qq-bargG)  depends on (m2/s)3
- This results in larger splittings at high values of MD between values of n for qg and gggG compared to qq-bargG.

- For n=2 qq-bar is not the dominate process, but for n>2 then this is the dominate process

| Process
MD = 1 TeV | n(pb)
Total) | n(pb)
Total) | n(pb)
Total) |
| --- | --- | --- | --- |
| qq-bargGKK | 4.1 
(0.16) | 1.6
(0.53) | 0.70
(0.78) |
| qggGKK | 9.6
(0.38) | 0.68
(0.22) | 0.096
(0.11) |
| qggGKK | 11.4
(0.45) | 0.77
(0.25) | 0.11
(0.12) |
| Total | 25.2 | 3.05 | 0.90 |

- Tevatron s=2 TeV MD = 1.2 TeV

- n=4

- n=2

- pTmin (GeV)

## G Emission: jet(s)+ET

**Search Selection**
-     jet ET1st 80 GeV, || <1.1 and ET>80 GeV
-     a second jet is allowed if ET2nd > 30 GeV
-     no isolated tracks in event (pT10 GeV)
**Main background** Z()+jets, W()+jets.

**G Emission:** **jet(s)+E****T**

**Results**
- Expected: 27416  Observed: 284 events.
- Relative uncertainty on the signal acceptance 25 %

**Limits**
- 95 % C.L. upper limit on number of signal events: 62

- 84 pb-1 Run Ib

|  | Run I : MD (TeV) > |  |  | Run II 85pb-1 |  |
| --- | --- | --- | --- | --- | --- |
| n | CDF
(K=1.0) | D
(K=1.0) | D
(K=1.34) | D
(K=1.3) | DELPHI |
| 4 | 0.77 | 0.66 | 0.73 | 0.68 | 0.84 |
| 6 | 0.71 | 0.63 | 0.65 | 0.66 | 0.58 |

**Predicted Data**
**Predicted invisible Z**
**Observed (84pb****-1****)**

**E****T ****(GeV)**

***CDF Run II result on the way!!***

## G Emission: jet(s)+ET

**Search Selection**
- Require 1 or 2 jets
- jet ET1st 150 GeV, || <1 & ET > 120 GeV
-        (*above Jet100** **trigger threshold*)
- if 2 jets ET2nd < 60 GeV
-        (to increase acceptance for signal events)
- no isolated tracks in event (pT10 GeV)
-        (*reduce EWK background*)
**Main background** Z()+jets, W()+jets.

**G Emission:** **jet(s)+E****T**

- 350 pb-1 Run II

- Run II search...!

**Run II Search for LED **

- larger data set compared to Run1!

- Signal Acceptance
- 9.4% (n=2), 11.9% (n=4)
- Expected # Events in 350 pb-1 for *M**D** *= 1 TeV
- 89.9 events (n=2), 26.5 events (n=4)

## G Exchange: ee

- We find good agreement with the Standard Model expectation
- and thus set an upper limit on the production cross section (times branching ratio)
- for the production of particles leading to this signature.
- We do this separately for spin-0, spin-1 and spin-2 particles
- since the experimental acceptance depends on the spin. We then interpret this cross section limit
- in terms of physics beyond the Standard Model:
- Z', RS Gravitons, sneutrino, technicolor, Little Higgs.

- The main source of background is Drell-Yan. Jets being misidentified as electrons (labelled "QCD") are another important source of background.

**Search selection**
- 2 two isolated e, ET > 25 GeV
- 2 central e (CC)
- or 1 central and 1 forward e (CP)

- Main Backgrounds

- Overall Identification efficiency:
- 	CC: 92.4 ± 0.4%
- 	CP: 79.2 ± 0.5%

**N****exp****=11.1 N****obs****=14 ****for**** M****ee****>300 ****GeV/c****2**
**N****exp****= 4.6  N****obs****=  9 ****for ****M****ee****>350 ****GeV/c****2**

- Apply energy dependent cuts for high mass efficiency

- Being updated to 370pb-1

## ee(PP): Comparison to Expectation

**ee(PP): Comparison to Expectation**

*New for Run II: *
*Plug ee increase acceptance!*

**Search selection**
- 2 two isolated e, ET > 25 GeV
- 2 forward e (PP)

- QCD dijets: jet is misidentified
- Larger effect in the plug region
-    than in central

**Main Non-Drell-Yan Background**

**N****exp****=2.7 ****±**** 0.7  N****obs****=8 ****for**** M****ee****>300 ****GeV/c****2**
**N****exp****=1.4 ****±**** 0.3  N****obs****=3 ****for ****M****ee****>350 ****GeV/c****2**

## G Exchange:

**Search Selection**
- 2 isolated  PT>20 GeV
- |1|<1, |2|<1.5*
- Veto cosmic rays using
- 	track-timing cuts

**Muon System**

- COT

- Time-of-Flight

- Solenoid

- Silicon Tracker

**|********| < 1.5**

**|********| < 1**

- 2 may include tracks w/o chamber information

**N****exp****=5.2 ****± ****0.3 N****obs****=6 ****for**** M****ee****>300 ****GeV/c****2**
**N****exp****=3.2 ****± ****0.2 N****obs****=1**** for ****M****ee****>350 ****GeV/c****2**

## G Exchange: 

**Backgrounds**
-    Standard Model diphoton production
-     (dominant at very high masses)
-    Fakes: -jet and jet-jet,
-      where jet fragments into a hard 0

**Search Selection**
- 2 isolated  ET>15 GeV
- 2 central   (CC)

**N****exp****=4.2****±1.0**** N****obs****=1 ****for**** M****ee****>300 ****GeV/c****2**
**N****exp****=1.5****±0.5**** N****obs****=1 ****for ****M****ee****>350 ****GeV/c****2**

- Standard Model

- Extra Dimensions

## Extracting G Exchange ll, Limits

- 95 % C.L. lower limits on string scale and upper limits on .BR(*G*→*ll*) and are placed using binned likelihood method

- ni : observed events
- i= Nisig + Nibkg (Resonant particles)
- i= Nisig() + Nibkg (LED spectrum)

- Likelihoods are integrated to give the final limits, taking into account the signal and background systematic uncertainties

- _Sources of systematic uncertainties:_
- Luminosity
- Acceptance (PDF, MC statistics...)
- Energy/Momentum scale resolution
- Selection Efficiencies
- Background statistics and normalisation

- 95 % C.L. upper limits on .BR(G→) are placed using ± 3 search windows around MG

- N95%=95%Nsig

## ADD ee Limits

- 		 Set a limit on the effective Planck scale (Ms4)
- 		        using invariant mass spectrum (1D fit)

- Gupta et. al. hep-ph/9904234

- Parameterise the cross section in terms of =/ s4, where =±1 (Hewett)                   **** =   ******SM** + ******INT **+ 2 ******KK**

- CDF Run I: 780 768

**987  959**

- Same as D0 dielectron limits – but their diEM better

## CDF RS Graviton Limits

**CDF RS Graviton Limits**

-  **ee** has largest acceptance at low mass
**  ******** **has largest acceptance at high mass
-  BR(**G****→******) =  2 * BR(**G→ee**)

| Channel | Luminosity
(pb-1) | MG(GeV/c2)
K/MPl=0.01 | MG(GeV/c2)
K/MPl=0.1 |
| --- | --- | --- | --- |
| ee | 200 | 200 | 640 |
|  | 200 | 170 | 610 |
| ee+ | 200 | 200 | 700 |
|  | 345 | 220 | 690 |

## Angular Distributions: ee

- can I say that these are ... - what deviations would we expect though?!

- Results consistent with the background

- cos* in Collins-Soper frame

- 1-D fits performed, but also study angular distributions

***Good agreement with SM prediction***

## Angular Distributions:  & 

**Angular Distributions: ******** & ******

****

- can I say that these are ... - what deviations would we expect though?!

- Results consistent with the background

- cos* in Collins-Soper frame

- Not used in limits – but still studied

****

## ee Update/Status

- ee,  200 pb-1 result publication underway
- ee being updated from 200 pb-1 to 370pb-1
- 	doing a blind analysis for new data for Mee>175 GeV 	reoptimised the id cuts for CC and CP event selection

***Status:*** unblinded and going for pre-blessing

##  Update

****** ****Update**

-       **Plug Calorimeter**

-     **Central Calorimeter**

**|************| ****< 1.04 **

**1.2<****|************|****<2.8**

- Investigating adding Plug data
- 	**** increased acceptance
- 	****** **extra backgrounds

- Nevents (2 ’s Et>15 GeV)
- Ntotal in region

- =

- RS Herwig MC

- 87%

- 29%

- 76%

- 95%

**+ **300%

**+**125%

*** **search being updated to 435 pb**-1 **and plug data added*

## Why acceptance gain adding plug  data decreases with MG

-  0211205 hep.ph

- (gg→G→)/(G→)

-  G at high mass are produced via qq, rather than gg
-  qq initiated photons are more centrally distributed than ff
- 	in graviton rest frame (=1)
-  G at high mass are more likely produced near rest  (=1)

- Angular distribution for graviton production and decay (=1)

-  beta represents the velocity of the decay produces, beta = sqrt(1-4m2/MG2) for particles of mass m

## G Exchange: jet jet

- Inclusive jet cross section from Run I was larger than theoretically predicted at high ET

**Sign of new physics?**

- PDFs with enhanced high x gluons can explain the high ET rise (SM explanation)

-  Run II (√s= 1.8  1.96 TeV)

- Higher cross section, ~ 2(5) x at 400 (600) GeV  probe higher ET

## G Exchange: jet jet

- Inclusive jet cross section from Run 2

- PTjet range increased by ~150 GeV/c
- Test of pQCD over almost 8 orders of magnitude

- Data and theory consistent within errors

-  Dijet channel suffers from the large QCD background
-  However, high statistics in dijet samples allow the exclusion (or discovery?) of new particles that have a small fraction of the QCD dijet cross section

## Run II G Exchange: jet jet

_**Analysis Strategy**_
- Fit the mass spectrum to a smooth background parameterization plus a narrow resonance
- Search for bumps comparable with the mass resolution.
- Since new particles with a natural width significantly smaller than the mass resolution appear as a resonance of the same line shape.
- The poor dijet mass resolution allows us to search for many particles with the resonance shape of a single particle.

**Search Selection**
- 2 highest ET jets selected
- from inclusive jet samples

- For each new particle mass, compute likelihood vs new particle cross section
- Find 95% CL upper limit on new particle cross section

- Being updated to      390 pb-1 !

## UED Run I Multi-lepton Search

- 3 leptons from the same primary vertex
- remove bad runs, cosmics, Z’s, ’s, and J/’s.
- at least one e+e- or +- pair
- invariant mass of the 2 closest leptons > 5 GeV/c2
- opening angle of the 2 highest PT leptons < 170
- select non- events
- lepton isolation < 4 GeV
- missing energy > 15 GeV

- Adapted from Run I SUSY tri-lepton analysis

- Observe no evidence
- Set the upper limits ****total = 7.9 pb at 95% CL, converting to extra dimension radius limit of 280 GeV.

**Search Selection    **

- 87.5 pb-1 Run IIB SUSY dilepton sample

## Summary and Outlook

-  Searches for ED have been performed in many channels at CDF
-  No evidence of deviations from Standard Model expectation observed
-  Best limits obtained
- ADD   jets+ET, ee +   ~ 1 TeV
- RS     (345pb-1)m1 ~ 220 to 690 GeV for k/MPl 0.01 to 0.1
-           *ee* +    (200pb-1) m1 ~ 200 to 700 GeV for k/MPl 0.01 to 0.1
-        UED  extra dimension radius limit of 280 GeV
-  Many updates, new results and publications on their way....
-            *ZZ* channel
-  Tevatron Run IIa (2 fb-1) has a promising observation potential  	             and should be in a position to discover ED, if they exist,
-              ADD: up to about MS = 2 TeV
-              RS: m1 from 0.5 to1 TeV for k/MPl 0.01 to 0.1

**Look out this summer for new CDF results!**

##          constraints 

-          constraints

- RS

- m1 (GeV)

- 0.20
- 0.10
- 0.07
- 0.05
- 0.03
- 0.02
- 0.01

- 1000   2000   3000   4000   5000

- Allowed Region

- Sridhar hep-ph 0103055

## Diphoton          constraints

- hep-ph 0103055

- Diphoton production at Tevatron Run II
- sensitive to mass of first KK graviton resonance (m1) : 700-1150 GeV

- LHC:  can probe first graviton excitation up to ~ 3.5-5.5 TeV

- 200 220 240 260 280

- m0 (GeV)

- K/MPl

- 0.1
- 0.08
- 0.06
- 0.04
- 0.02

- s = 2 TeV
-  L = 2fb-1

- 95 % C.L.

- 95 % C.L.

**Tevatron**

**LHC**

- RS