# Presentation: 181178

## Recent results on top quark, electroweak and new physics searches from CDF

- Simona Rolli
- Tufts University
- on behalf of the CDF collaboration

- Simona Rolli, Fermilab W&C seminar

## Introduction

- Exciting time now at CDF !
- frenzy activity in physics analysis

- Optimize event selections for SM physics and new physics as in both cases the composition
- of the samples are important

- Cross sections for various physics processes vary over
- many orders of magnitude:
-     processes of interest are often buried under heavy background
-     need good rejection factors, selection and analysis strategies

- Common datasets

- Common identification/reconstruction cuts

- Simona Rolli, Fermilab W&C seminar

## Outline of the talk

**CDF II detector and current datasets size**
**Physics Objects, Signatures and Results**
**Leptons-only final states (and ****isolated tracks)**
- Z production
- Drell-Yan studies
- dilepton searches
**... ****+ Missing Energy****  and Photons**
- W production
- Multibosons
- excited electrons
- GMSB in diphoton + ET
**... ****+ Jets and heavy flavors**
- Leptoquarks
- Top
- Higgs

- Simona Rolli, Fermilab W&C seminar

## Run II Luminosity 

- Run II Luminosity

- Tevatron has delivered
-      ~430 pb-1
- We have ~350pb-1 on tape.
- Analyses presented here are using  from72 pb-1 to 240 pb-1 of data
- Error on luminosity is ±6%
- 1.6% due to CLC systematic error on CLC rate
- 4.0% due to CLC acceptance sys
- 3.8% due to  limited by knowledge of pp inelastic cross section.

- Simona Rolli, Fermilab W&C seminar

## CDF Run II Detector

- From Run I:
- Solenoid
- Central muon system
- Central calorimeter

- New For Run II:
- Front-end DAQ
- Trigger
- Track (L1) and Displaced Track (L2)
- Silicon Tracker (8 Layers) (  2.0)
- Central Outer Tracker (  1.0)
- Plug Calorimeters (1.0    3.6)
- Extended Muon Coverage (  1.5, gaps filled in)

- Simona Rolli, Fermilab W&C seminar

## Electrons & Muons

- Simona Rolli, Fermilab W&C seminar

## Inclusive Z cross section

******BR(Z********ee) = 255.2  ********3.9(stat)  ******** 5.5 (sys) ******** 15.3(lum) pb**
**              ********BR(Z********) = 248.9  ********5.9(stat) ****+7.0****-6.2**** (sys) ******** 14.9(lum) pb**

- Full Acceptance

- Extended measurements
- of cross  section are
- well advanced

- Simona Rolli, Fermilab W&C seminar

## Drell-Yan Measurements

- p

- angle between
-  p and e−

- Simona Rolli, Fermilab W&C seminar

## Searches in dileptons

- Simona Rolli, Fermilab W&C seminar

## Searches in dileptons ( cont’d)

- Calculate the acceptances for
- resonant states for 3 different
- spin assumption (0,1,2)

-  _Randall-Sundrum graviton model_
-         4-dimensional metric multiplied by *warp* factor
-         exponentially changing with the additional dimension
-           Generating a large hierarchy does not require a large rc
-        The coupling of individual KK states to matter is set by
-        the weak scale  (parameters : MG and k/MP lanck)
-        _KK states can be observed as spin 2  resonances_

- Simona Rolli, Fermilab W&C seminar

## Searches in dileptons (cont’d)

- Simona Rolli, Fermilab W&C seminar

## Search for doubly charged Higgs

- Doubly charged Higgs are members of Higgs triplets occurring in several types of models

-  extensions of the Higgs sector of the SM
-  left-right symmetric models
-  SUSY left-right symmetric models

- Same sign leptons signature

- Very small background!

- At the TeVatron doubly charged Higgs can
- be  paired-produced ( Z exchange) or
- singly produced ( WW fusion)

- Simona Rolli, Fermilab W&C seminar

## Photons & Neutrinos

- Simona Rolli, Fermilab W&C seminar

## Inclusive W cross section

**Transverse Mass - W********e******

**Missing Transverse Energy**

**Transverse Mass - W******

**Control of background**

- Simona Rolli, Fermilab W&C seminar

## Inclusive W cross section (cont’d)

- Following  the same strategy
- pursued in the || <1 region,
- full tracking is used in the
- forward region

- EM cluster is matched to a 3D
- track reconstructed using  the
- Silicon detector only in the
- region 1 < || < 2.8

- ****** ******** **BR(We) = 2874  34 (stat)  167 (sys)  172 (lumi) pb

- Simona Rolli, Fermilab W&C seminar

## Summary and X-Sections Ratio

- Simona Rolli, Fermilab W&C seminar

## Di-boson Signals

- W

- Z

- Triple Boson
- Coupling

- Non SM!

- Test of gauge couplings ( as predicted by the SM) and a window
- on new physics

- Simona Rolli, Fermilab W&C seminar

## W and Z

- FSR

- ISR

- Simona Rolli, Fermilab W&C seminar

## W

******(W********)********BR(W********l********) = 19.7**
**                                    ******** ****1.7 (stat) ******** 2.0 (sys)**
**                                    ********  ****1.1 (lumi) pb**

**For E****T****(********) > 7 GeV and ********R(l, ********) > 0.7:**
******(W********)********BR(W********l********) (Theory) = 19.3 ******** 1.4**

- Simona Rolli, Fermilab W&C seminar

## Z

******(Z********)********BR(Z********ll) =5.3**
**                                ******** ****0.6 (stat) ******** 0.4 (sys)**
**                                ********  ****0.3 (lumi) pb**

**For E****T****(********) > 7 GeV and ********R(l, ********) > 0.7:**
******(Z********)********BR(Z********ll) (Theory) = 5.4 ******** 0.4**

- Simona Rolli, Fermilab W&C seminar

## Excited electrons

-  Observation of excited states of quarks and  leptons might  confirm the hypothesis that  they* *are  not elementary particles , but composite states

-   Select events with ee in the final state
-   Look for resonance in M(*e*)
-   SM backgrounds :
- Z  + DY , Z+jets, WZ, Multi-jets,   +jets, ...

- Expect 3 events, observe 3 events

- CDF searched for excited electron (*e**)
- using high pt electron data (L=200 pb-1)

- At Tevatron, *e**  can be produced via contact
- interactions or gauge mediated interactions

- Simona Rolli, Fermilab W&C seminar

## Excited electrons

- 4 EM candidates
- Could be ZZ event!

- Simona Rolli, Fermilab W&C seminar

## WW

- Tight lepton selection complemented
- by lepton + tracks selection

******WW**** =**** ****19.4 ± 5.1 (stat) ± 3.5 (sys) ± 1.2 (lumi)**** **

- Larger fakes
- contamination and
- uncertainty

- Further step towards limits on
- anomalous WWZ, WW
- coupling

- Simona Rolli, Fermilab W&C seminar

## WW

- Simona Rolli, Fermilab W&C seminar

## SUSY searches in diphoton + ET

- GMSB scenario
- NLSP = 01  G

- Sample selection (84 pb-1)
-  2 central photons ET > 13 GeV
-  cosmic rays and beam halo rejection

**M(C****1****)  > 113 GeV @ 95% C.L.**

- Simona Rolli, Fermilab W&C seminar

## Jets

- Simona Rolli, Fermilab W&C seminar

## Search for Mass Bumps in Dijets

- Inclusive jet samples
- MET/ET < 6 and E < 2.2 TeV
- 2 highest ET jets selected
- fit of the mass spectrum with a simple background parameterization and search for bumps comparable with the mass resolution.

-  no significant evidence for a new particles...yet

- Run 152507 event 1222318
- Dijet Mass = 1364 GeV/c2
- cos q* = 0.30
- z vertex = -25 cm

- Simona Rolli, Fermilab W&C seminar

## Search for Mass Bumps in Dijets

- Complementary to dilepton search

- ExtraDimensions

- Simona Rolli, Fermilab W&C seminar

## Several extension of the SM model (GUTS, Technicolor, Compositeness, RPV-SUSY)
assume an additional symmetry between leptons and quarks

- Several extension of the SM model (GUTS, Technicolor, Compositeness, RPV-SUSY)
- assume an additional symmetry between leptons and quarks

- 30% increase in
- cross section at RunII

- Leptoquarks

- Carry both lepton (L) and baryon (B) numbers
- Couple to quark and lepton of the same generation

- At the TeVatron they are
- pair produced

- Their decay is controlled
- by  = BR (LQlq )

- Experimental signature:
- _high P__T__ isolated lepton(s)_
- _and/or E__T __+ 2 jets_

- 3 generations

- Simona Rolli, Fermilab W&C seminar

## 1st generation LQ

- 111GeV/c2    ( =0.01)
- 124GeV/c2    ( =0.05)
- 135 GeV/c2    ( =0.1)
- 161 GeV/c2   ( =0.2)
- 197 GeV/c2   ( =0.5)
- 232 GeV/c2   ( =1.0)

- Signature:
- 2 electrons and 2 jets
- electron, ET and 2 jets
- ET and 2 jets

- Simona Rolli, Fermilab W&C seminar

## 2nd generation LQ

- Tight ’s selection complemented by  + track selection

- 2 events seen after analysis cuts

- Signature: 2 muons and 2 jets

- Background:
-     Z + 2 jets
-     top
-     QCD fakes

- expected 3.15  1.17

- M(LQ) > 240 GeV/c2 @ 95% C.L.

-  =BR(LQq) = 1

- Simona Rolli, Fermilab W&C seminar

## LQ search in jj

- 124 events seen after analysis cuts

- Signature: Large MET and 2 jets

- ’ =BR(LQq) = 1

- Expected =11814

- Sample Composition:
-   W/Z + jets
-   top
-   QCD fakes

- M(LQ) > 117 GeV/c2 @ 95 % C.L.

- Simona Rolli, Fermilab W&C seminar

## Top Quark

- EW single-top production,
- x2 smaller rate, not (yet) seen

- Simona Rolli, Fermilab W&C seminar

## Top Data Samples

- Samples are defined by counting leptons and jets

- Cross section results validate top-enriched samples

- can also point toward new physics

- Simona Rolli, Fermilab W&C seminar

## Top Dilepton Cross Section

- Lepton + track sample has looser ID requirements for second lepton
- It is sensitive to  lepton final state

- Tight e/ selection
- complemented by
- e/ + track selection

- Interesting place
- to follow up on
- Run I anomalies

- Simona Rolli, Fermilab W&C seminar

## Heavy Flavor jets: tagging tools

- B hadrons in top signal events

- Simona Rolli, Fermilab W&C seminar

## Cross Section Results using Tagging

- Backgrounds estimate in the lepton + jets sample carried on:
-   using data as much as possible (non-W QCD, fake tags)
-   using MC calculations for diboson and W + heavy flavor

- Counting experiments with vertex tag and soft muon tag in 3,4-jet bins

- Simona Rolli, Fermilab W&C seminar

## Kinematic Fits to Lepton + Jets Sample

- This signature suffers from large
- W+jets background. Isolate signal using **kinematics **before and after tagging

- 1 high pT lepton(e,)

- Large Missing ET

- 3 central jets

- Simona Rolli, Fermilab W&C seminar

## Lepton + jets: NN results

- Statistical and  systematic uncertainties
- improved compared to single-variable fit.

- ttbar and W+jets kinematics differ modestly, but do so in several  different variables.
- Develop a neural net to use this information optimally.

- Good separation
- between signal
- and background

- No b tagging information is used

- Simona Rolli, Fermilab W&C seminar

## Hadronic top

- Signature: six jets, 2 tagged
- Large QCD background

- Kinematical selection of the sample
- complemented by b-tagging of at least
- one jet

- Cross Section is a function of the
- number of observed tagged jets

- Simona Rolli, Fermilab W&C seminar

## CDF Top Cross Section Summary

- Simona Rolli, Fermilab W&C seminar

## Cross Sections Ratio

- Ratio of measured ’s (R) tests that assumption:
-  Should be unity
-  tests consistency with SM

- Probability distribution for R
- 0.46 <R < 1.45+0.83-0.55 @ 95% CL

- Limits on non SM Br’s of top (simple model)
- R < 0.46 @ 95% C.L.
- for additional all-hadronic tXb decays

- Cross-section values assume tWb always, never tXb.

- Many systematic uncertainties cancel
- Independent of theory value of theory input (PDF’s, mt)
- Sensitivity to non-SM decays of top, e.g. t H+b,
- Different tan  gives different mix of *ll/lj*

- Simona Rolli, Fermilab W&C seminar

## Lower jet multiplicity

- The 2 jets bin is an interesting sample
-      Single Top (constraining Vtb )
-      Higgs
-      Exotics

- Large (QCD) background
- Small cross sections

- Simona Rolli, Fermilab W&C seminar

## 2 Jets Bin: Single Top Cross Section

- Search strategy employs
- Likelihood fit to HT (combined search)
- Likelihood fit to b Q*(t-channel only)
- Q of lepton,  of light quark jet

- Final state is W + exactly 2 jets
-                  Tag one b jet

- Cross section limits at 95% confidence level:

- Combined search:  < 13.7 pb
- T-channel search:  < 8.5 pb

- Observed as many events as expected

- Simona Rolli, Fermilab W&C seminar

## 2 Jets Bin: Higgs Search

- Selection:
- High pt lepton data
- One high pt central *e* or , large MET (MET>20 GeV)
- 2 jets (at least one is tagged as b-jet)
- Veto events with >1 lepton (suppress ttbar)

- Backgrounds:
- Mistags
- Wbb, Wcc, Wc
- QCD
-  tt, single t, di-boson, Z(tt)

- S/B = 0.054

- Simona Rolli, Fermilab W&C seminar

## Higgs Search (cont’d)

- Include forward electron
- Improvement jet energy resolution
- Improve b-tagging
- Combine with other channels

- Improved limit over Run1, but sensitivity
- of current search is limited by statistics

- Simona Rolli, Fermilab W&C seminar

## Top Mass Measurement Challenges

- Traditionally, likelihood fit methods have
- been applied: data is fitted to most likely
- mass template from Top MC

- Many combinations of leptons and jets: which one is correct?

- Choose assignment kinematically most consistent with top
- Use all combinations, but weight them

- Link observables to parton-level energies
-     Accurate detector simulation vital to
-      precision physics measurements
-    Large systematic uncertainty from energy scale

- Currently we are exploring the possibility of  adding event kinematic information, possibly including matrix element information

- Simona Rolli, Fermilab W&C seminar

## Top Mass Results: template fits

**   **

-  22 vertex-tagged events from lepton+4 jet sample

- Reconstruct mt via kinematic fit
- Choose single combination with best
- 2 from over-constrained fit
- Compare to templates from
- Top signal MC
- Backgrounds (fixed relative)

- 6 dilepton candidates in 125.8 pb-1

- Underconstrained kinematic fit
- For each lepton-b pair assignment
-      Calculate best raw mass, from
-       most probable combination
-       Fit to signal and background templates

- Mtop = 175  17(stat.) 8(syst.) GeV/c2

- Simona Rolli, Fermilab W&C seminar

## New Run I mass combination

- Combination Method:
- weighted mean of un-correlated measurements
- numerical minimization of 2 for correlated measurements

- New Higgs  mass
- constraint

- Simona Rolli, Fermilab W&C seminar

## Dynamical Likelihood Method

- Simona Rolli, Fermilab W&C seminar

## Results

- Event Likelihood distribution:

- Further corrections to the  transfer function
- (expected bckg, template mass) are applied

- Minimization

- More information
- Less statistical uncertainty

- 22 tagged l+4 jets events

- Simona Rolli, Fermilab W&C seminar

## Conclusions

- Many exciting results are currently produced at CDF
- first high PT physics papers will be submitted very soon!

- Many of our results interplay nicely :
- From testing the SM processes to searches for Exotica
-        same signature, different physics

- The  Puzzle is becoming more and
- more interesting!

- Simona Rolli, Fermilab W&C seminar

## Backup Slides

- Simona Rolli, Fermilab W&C seminar

## COT aging issues

- Simona Rolli, Fermilab W&C seminar

## Silicon tracking efficiency

- Simona Rolli, Fermilab W&C seminar

## Rate of mis-measured tracks

- Simona Rolli, Fermilab W&C seminar

## Forward Tracking efficiency

- Simona Rolli, Fermilab W&C seminar

## (W) 

- Simona Rolli, Fermilab W&C seminar

## Run 1 Dileptons

- Simona Rolli, Fermilab W&C seminar

## Old Higgs mass limit from MTop

- Simona Rolli, Fermilab W&C seminar

## Z’ limits

- Simona Rolli, Fermilab W&C seminar