# Presentation: 381524

## Electroweak Measurements at CDF

- _A. __Sidoti_
*For the CDF Collaboration*
*LPNHE- Universite Paris VI “Pierre et Marie Curie” *
*(Paris, France)*

***Electroweak Measurements at CDF***

- Lake Louise Winter Institute
- (Canada)
- February  20-26, 2005

## Why Electroweak Measurements?

***Why Electroweak Measurements?***

- Precise Electroweak predictions
- Challenge for Electroweak physics measurement
- Constrains the Standard Model
- OR
- Appearance of Physics Beyond SM
- Also crucial as input for LHC physics program:
- Input to Parton Distribution Functions
- Some Tevatron signals will be LHC background
- After LEP era stepping into Tevatron era:
-  N(Z)@Tevatron > N(W)@LEP

**Notes:**
Discrepancies

## Production Processes at Tevatron

- Outline:
- W and Z cross sections
- Asymmetries (W and Z)
- Diboson production
- W mass measurement

- Yield ~104 Ws , ~103 Zs

**Notes:**
COmpared to previous and future hadronic colliders
Total yield analyzed here

## W/Z  Gauge Bosons and Event Topology

**At hadron colliders**
**Use clean leptonic decays**

***W/Z  Gauge Bosons and Event Topology***

- W **±****  **energetic lepton + E**T**

- Z energetic opposite sign leptons

- ET>25GeV

- PT>20GeV

- PT>20GeV

## Inclusive W/Z Cross Sections

- Good agreement with NNLO
- Systematics limited measurement
- Uncertainties: Luminosity (6%)
- 		          PDFs(2%)

****(pp→W)xBF(W→l****)**Th,NNLO**=2687±54pb

****(pp→Z)xBF(Z→ll)**Th,NNLO**=251.3±5.0pb

**Notes:**
Ricordarsi di dire all leptonic modes, all subdetectors

## Indirect W Width Measurements

- R: cross section measurement ratio:

- Many systematic uncertainties cancel out(Luminosity)

- Checking internal consistency of SM with direct (W) measurement

- Indirect W Width measurement

**PDG**

**Notes:**
Qui devi dire che abbbiamo gia` una misura migliore del RunIincertezza 
della world average 

## W Asymmetry

***W Asymmetry***

- Sensitivity to PDF distributions(u/d ratio):
- u carries more momentum than d

- Observable quantity is lepton rapidity:
- Convolution of W asymmetry and V-A interactions
- Charge ID at high |****|  is crucial: Use of calorimeter seeded tracks

- Larger ET: electron direction closer to W direction.
- Production asymmetry enhanced.

- Lower ET: decay asymmetry enhanced

**Asymmetry**

**Asymmetry**

**∫**Ldt=170pb-1

**Notes:**
Dire del tracking innovativo fino ad alto eta
Spiegare meglio le due regioni in Et
Two energy bins increse on PDF sensitivity
“Devono” andare nelle pdf 

## DiBoson Production

***DiBoson Production***

- For W/Z Photon Id is crucial:
- Main backgrounds:
******0****→******
- jets faking photon
- Fake Rates:
- 0.2% @JetE**T**=10 GeV
- 0.05% JetE**T**>25GeV

- Test Gauge Boson Self Interactions
- SM Higgs searches
- Resonance searches: Look for excess in kinematical distributions: ET(****) , 3body mass, lepton P**T**

- Complementarity with LEP experiments:
- Probing at higher √*s*
*W-*******final state

## W Production

**CDF Run II**

- Baur, Han, Ohnemus(1993,1998)

- ∫Ldt≈200 pb-1

- ET() Distribution

**Notes:**
Dire che si ha un ottimo controllo sulla energia del fotone

## Z- Production

## Z Kinematical Distributions

- ET() Distribution

- 3Body Mass

- No significant excess with
- respect to SM expectations

**0    5  10  15  20  25  30  35  40 E****T****(********)**

- BSM Predictions

******=5 ********=5**

******=7 ********=0**

******=0 ********=3**

**SM**

## WW Production

## WZ and ZZ Searches

- (pp→ZZ/ZW+X)NLO=5.0±0.4 pb-1

**∫**Ldt = 194pb-1

- (pp→ZZ/ZW+X)**CDF**<15.2 pb @95% C.L.

- Extracted a limit for cross section
- Measurement possible with available collected statistics

- Entangled Processes

## W Boson Mass

- Bound to SM Higgs Mass
- Indirect searches of physics BSM
- Need accuracy better than 10**-3**
- Fit of transverse mass distribution
- (W) direct measurement
- Result:
- With L=200pb-1  ****M**W**=76 MeV/c2 (e+****) combined
- →Already better than RunI CDF
- With 2fb-1 expect ****(Mw)~30MeV/c2
- Will use next PDFs fits with CDF W charge asymmetry measurement

- Top Mass(GeV/c**2**)

## Perspectives and Working Areas

- Inclusive cross section, widths, BF in all leptonic channels.
- Working on Differential Cross Sections
- Z asymmetries
- 	Quark gauge bosons couplings
- W asymmetries
- 		Shall be included in 2005 PDFs
- 	  	W Rapidity reconstruction
- Diboson  production cross section (increase statistics)
- 		Extracting Triple Gauge Coupling
- 		Looking for hadronic final states WW→(qq’)(l******l**)
- W Boson Mass Measurement: unveiling the central value
- Direct (W) measurement

***Perspectives and Working Areas***

**Notes:**
Dare prospettive,
Vivremo a lungo con la massa della W

## O fortunati, quorum iam moenia surgunt!

- Verg., Aen., I 437

- Electroweak RunII Publications
- hep-ex/0406078: “Inclusive W and Z Cross Section”
- hep-ex/0501023: “W Charge Asymmetry”
- hep-ex/0411059: “Z Forward Backward Asymmetry”
- hep-ex/0410008: “W gamma, Z gamma production”
- hep-ex/0501050: ”WW Production”
- hep-ex/0501021: “WZ/ZZ Searches”

## Backup Slides

## The Run II CDF Detector

## Tevatron Performances and Perspectives

## Z Boson Cross Sections(e,)

- Muon Channel
- PT>20 GeV/c

- Electron Channel
- Electron ||<2.8
- ET>25 GeV

## 20 Years of W and Z at hadronic colliders

- NNLO

- NNLO

## W Boson Production

- Electron Channel

- Muon Channel

- e

****

- •B(W-->e****) (pb)

- Region

- Events

- |****|<1.0

- 1.1<|****|<2.8

- |****|<1.0

- 57109

- 194

- 64

- 72

- 37584

- Bkg

- 4.4

**2786±16****stat****±64****sys****±166****lum**

- 8.7

- 10464

- 9.5

**2874±34****stat****±167****sys****±172****lum**

**2786±12****stat****+65****-55****sys****±172****lum**

## Z Asymmetry

- A**FB** arises from Axial and Vector couplings
- Z and  interference term

- Measurement limited by statistics
- Complementary to LEP
- measurement far from the Z pole
- Sensitivity to heavy neutral bosons (Z')
- Extract quark, electron couplings and sin**2********W****Eff**

**Notes:**
Importante stressare lo Z’
Chie e` A e chi e` B

## Couplings Results

- Quark Couplings:

- Electron Couplings:

******2****=10.40/11**

******2****=13.14/13**

**sin****2****θ****W****Eff****=0.2238±0.0040****(stat)****±0.0030****(syst)**
******2****=12.50/14**

## From R to (W)

- 20+ years of W and Z bosons at hadron colliders

- Indirect W Width measurement

- From R to (W)

## Tau

- Taus are difficult at hadronic colliders
- →hadrons (h) look like jets
- Need to combine:
- Tracking (||<1)
- Calorimetric Clusters ****x **** (0.1 x 15**o**)
- **o** reconstruction (showermax inside EM Calorimeter resol. ~few mm)
- Reconstruction Efficiency:
- ~70%   @15 GeV
- ~85%   @25 GeV
- ~95%   @40 GeV
- It is possibile to trigger on taus:
- Lepton + Track trigger (lepton + isolated track). Final states:******h**+******(e,********)**+X,**h**+(e,****)+X

## Tau Physics Measurement

- Z->teth

- Track Multiplicity: 1 and 3 prongs

## W Production

***W************ Production***

*q*

*q'*

*l*

**

*W*

*q*

*q'*

*l*

**

*W*

- WW****

- FSR

- ISR

**CDF Run II**

*q*

*q'*

*l*

**

*W*

- Baur, Han Ohnemus(1993,1998)

- ∫Ldt≈200 pb-1

## Z Asymmetry

**CDF Run I (~110 pb****-1****) **

## Calculating AFB

- cos* in Collin-Soper frame
**Minimize ambiguity in the incoming quark Pt**
- cos*>0 Forward
- cos*<0 Backward

- Calculating AFB:

- Z0/*

- Z0/*

- PZ =0

- Z-Axis

- lab frame

## Data-MC Comparisons

- CDF II Preliminary

## Data-MC: Cos(*)

- CDF II Preliminary

## Couplings Results

- Quark Couplings:

- Electron Couplings:

**sin****2****θ****W****Eff****=0.2238±0.0040****(stat)****±0.0030****(syst)**
******2****=12.50/14**

******2****=13.14/13**

- sin**2**Θ**W****Eff**** **Measurement:

## W Asymmetry

- Charge ID is crucial at high rapidity

**Anastasiou, Dixon, Melnikov, Petriello, **
**Phys Rev D 69, 094008 (2004) **

## Raw Asymmetry

***Raw Asymmetry***

- Corrections to extract true asymmetry:
- Charge misidentification rate.
- Background subtraction.
- Both bias the asymmetry low → dilution.
- Measured in each  bin.
- Uncertainties in corrections go directly in A.

**Curve is just to guide the eye.**

-  < 1 ~ linear

**Shape is convolution of**** ****A****(y****W****) ****and V-A**** **
**Sign switch @ ******** > 2**

## W Asymmetry

**xf(x,Q****2****)**

**log(x)**

- [http://durpdg.dur.ac.uk/hepdata/pdf3.html]

- Run I Result

## Phoenix (Calorimeter-Seeded) Tracking 

**Phoenix SiTrack**

**Cal. Seed Tracks**

**Zoom into Silicon:**

**Use both central and **_**forward**_** electrons! |********< 2.8**

- Two points and a curvature
- define a helix:
-  Primary collision vertex position.
-  Fitted position of calorimeter shower maximum.

## W production

## W

****R(****-l)

## Z-

## Z Production

***Z************ Production***

## WW production

**Notes:**
Processo a soglia
Ppbar diverso da pp

## WW->e+

## WW->e+ or ZZ->ee ?

## W Boson Mass background

## W Boson Mass

## WW production: Kinematical Distributions

- No significant excess so far

- Lepton P**T**

- Dilepton Invariant Mass