W properties AT CDFW properties AT CDF

J. E. GarciaJ. E. Garcia

INFN Pisa

OOutlineutlineC

orf

u S

um

mer

Inst

itute

Corf

u S

um

mer

Inst

itute

Septe

mber

10 th

2

1.CDF detector

2.W cross section measurements

3.W mass and width

4.W charge asymmetry

5.Summary

Jose E. Garcia – INFN Pisa

W @ TW @ TevatronevatronC

orf

u S

um

mer

Inst

itute

Corf

u S

um

mer

Inst

itute

Septe

mber

10 th

3

Precise Electroweak measurementsPrecise Electroweak measurements

Check Standard ModelCheck Standard Model

Provide evidence of physics beyond SMProvide evidence of physics beyond SM

Important input to LHC physics programImportant input to LHC physics program

Tevatron is for the next years the only accelerator than can produce Ws directly:

~ 90,000 W e () events per week. With a week luminosity of 15 pb-1.

Forward ElectroMagnetic and Hadronic calorimeters (“PLUG”).

(1 < || < 3)

Drift chamber (COT)Drift chamber (COT)

Corf

u S

um

mer

Inst

itute

Corf

u S

um

mer

Inst

itute

Septe

mber

10 th

4

CDFCDF II II

Silicon trackerSilicon tracker

a.a. L00 L00 (1 SS, r-(1 SS, r-))

b.b. SVXII SVXII (5 DS)(5 DS)

c.c. ISL ISL (2 DS |(2 DS || > 1, 1 DS || > 1, 1 DS || < 1)| < 1)

W PW Productionroduction

W decay signatures (lepton channels):

Isolated, high pT lepton with large missing

transverse momentum

Muon channel

Corf

u S

um

mer

Inst

itute

Corf

u S

um

mer

Inst

itute

Septe

mber

10 th

5

Electron channel

Corf

u S

um

mer

Inst

itute

Corf

u S

um

mer

Inst

itute

Septe

mber

10 th

6

W PW Productionroduction

MT (GeV/c2)

Corf

u S

um

mer

Inst

itute

Corf

u S

um

mer

Inst

itute

Septe

mber

10 th

7

W CW Crossross S Sectionection inin P Pluglug

Candidate events 64 pb-1

Estimated background

Acceptance efficiency

10,461 (8.7± 2.4) % (5.2 ± 0.2) %

BR(We) = 2.874 0.034stat 0.167sys 0.172lum nb

Update of the this measurement is in progress:

• Larger statistics ( ~ 220 pb-1)

• Much improved tracking efficiency

• Start re-blessing process this September

Candidate events 220 pb-1

Estimated background

Acceptance efficiency

61,309 10.4 % 8.7 %Preliminary

2874

W CW Crossross S SectionectionC

orf

u S

um

mer

Inst

itute

Corf

u S

um

mer

Inst

itute

Septe

mber

10 th

8

Overall good agreement with the NNLO calculations

Accuracy limited by the systematic effects

Uncertainties dominated by luminosity measurements (~6%)

Other systematics dominated by PDF uncertainties (~2%)

LLeptonepton U UniversalityniversalityC

orf

u S

um

mer

Inst

itute

Corf

u S

um

mer

Inst

itute

Septe

mber

10 th

9

From the measurements of the W W e e and W W μμ cross sections obtain cross section ratio U:

Many systematic uncertainties cancel out

In the same way from W W e e and W W ττ cross sections:

012.0998.0 eg

g

sysstateg

g04.002.099.0

2

2

)(

)(

)(

)(

eg

g

eW

W

eWBR

WBRU

W IW Indirectndirect W WidthidthC

orf

u S

um

mer

Inst

itute

Corf

u S

um

mer

Inst

itute

Septe

mber

10 th

10

CDF II (e+)

CDF II ()

R: cross section ratio measurement:

Many systematic uncertainties cancel out (e.g. luminosity)

Allows for an internal consistency check of the Standard Model with direct Γ(W) measurement

)(

)(

ZBR

WBRR

Channel (W)(MeV)

e+ (72 pb-1) 2079 ± 41

(194 pb-1) 2056 ± 44

World Average 2118 ± 44

SM Prediction 2094 ± 3

)(

)(

)(

)(

)(

)(

W

W

Z

Z

Zpp

WppR

PRL94, 091803(2005)

W W Mass MeasurementMass MeasurementC

orf

u S

um

mer

Inst

itute

Corf

u S

um

mer

Inst

itute

Septe

mber

10 th

11

Tevatron Run II has now 6 times Run I CDF, DØ data sets. CDF has analyzed first 200 pb-1 of data and determined uncertainties. Run II goal is to reduce uncertainty to less than 40 MeV.

LEP: 80,447 42 MeV Tevatron: 80,454 59 MeV (Run I)

ΔMW= 34 MeV

Precise knowledge of MW

constrains SM MH,

as well as hypothetical new particles.

W propagator includes H, tb and hypothetical new particle loops.

W W Mass MeasurementMass MeasurementC

orf

u S

um

mer

Inst

itute

Corf

u S

um

mer

Inst

itute

Septe

mber

10 th

12

22 )()()()( TTTTT

pp EEWm

Calorimeter energy scale Tracking momentum scale

NLO event generator Model detector effects

DATA W Mass templates +

Backgrounds

Binned likelihood fitBinned likelihood fit

W Mass

W W Mass MeasurementMass MeasurementC

orf

u S

um

mer

Inst

itute

Corf

u S

um

mer

Inst

itute

Septe

mber

10 th

13

CDF RUN IIPRELIMINARY

CD

F R

UN

II

PR

EL

IMIN

AR

Y

W W Mass MeasurementMass MeasurementC

orf

u S

um

mer

Inst

itute

Corf

u S

um

mer

Inst

itute

Septe

mber

10 th

14

CDF RUN IIPRELIMINARY

mT fit

mT(μν)(GeV)

CDF RUN IIPRELIMINARY

mT fit

mT(eν)(GeV)

Using 200 pb-1 of Run II data CDF estimated the uncertainty on MW

Total uncertainty: Total uncertainty: 76 MeV76 MeV ( (e+e+ combined) already lower than CDF combined) already lower than CDF Run I (79 MeV)Run I (79 MeV)

Systematic Electrons (Run 1b) Muons (Run 1b)Lepton Energy Scale and Resolution 70 (80) 30 (87)

Recoil Scale and Resolution 50 (37) 50 (35)Backgrounds 20 (5) 20 (25)

Statistics 45 (65) 50 (100)Production and Decay Model 30 (30) 30 (30)

Total 105 (110) 85 (140)

In the collision u quark inside proton carries higher fraction of momentum than d. W production is sensitive to u(x)/d(x).

W CW Chargeharge A AsymmetrysymmetryC

orf

u S

um

mer

Inst

itute

Corf

u S

um

mer

Inst

itute

Septe

mber

10 th

15

Use Ws to probe the proton structure

dyWddyWd

dyWddyWdyA w /)(/)(

/)(/)()(

pp

Observable quantity is electron rapidity

Convolution of W production asymmetry and V-A

decay

dyeddyed

dyeddyedA

/)(/)(

/)(/)()(

WXpp

W CW Chargeharge A AsymmetrysymmetryC

orf

u S

um

mer

Inst

itute

Corf

u S

um

mer

Inst

itute

Septe

mber

10 th

16

PRD71, 051101(2005)

Identification of the lepton charge is the key

Probability of missId is around ~4% at || ~2

SSummaryummaryC

orf

u S

um

mer

Inst

itute

Corf

u S

um

mer

Inst

itute

Septe

mber

10 th

17

Jose E. Garcia – INFN Pisa

RUN II CDF measurements are already better than results obtained RUN II CDF measurements are already better than results obtained in RUN I.in RUN I.

W mass has increased precision, expected to reach next year up to W mass has increased precision, expected to reach next year up to 30 MeV with 2 fb30 MeV with 2 fb-1-1

W charge asymmetry has been included in PDF’05 fitsW charge asymmetry has been included in PDF’05 fits

Direct W width measurement using Run II dataDirect W width measurement using Run II data

Results consistent with SMResults consistent with SM

BBackupackup S Slideslides

W properties AT CDFW properties AT CDF

J. E. GarciaJ. E. Garcia

Electrons

EM CalorimetersHigh PT Track

WW//Z IZ IdentificationdentificationC

orf

u S

um

mer

Inst

itute

Corf

u S

um

mer

Inst

itute

Septe

mber

10 th

19

• At hadronic colliders W and Z bosons decaying hadronically are overwhelmed by QCD background.

Identification trough leptonic decays

W Signature: Isolated Lepton and Isolated Lepton and EETT

Z Signature: Two Isolated Two Isolated Leptons (opposite Leptons (opposite charge)charge)

Muons

Muon DetectorsHigh PT Track

Neutrinos

Large Missing EnergyOnly Transverse (ET)

PPhysics withhysics with W’s W’sC

orf

u S

um

mer

Inst

itute

Corf

u S

um

mer

Inst

itute

Septe

mber

10 th

20 W boson identification is fundamental for many High-PW boson identification is fundamental for many High-PTT processes: processes:

W propertiesW properties

top searches ( tt top searches ( tt WW WW bbbb))

SM Higgs searchesSM Higgs searches

precision measurements sensitive to New Physics.precision measurements sensitive to New Physics.

It is a well known process, so it helps to set the basis for:It is a well known process, so it helps to set the basis for:

Understanding of the detector Understanding of the detector

Understanding of the backgroundsUnderstanding of the backgrounds

Lepton identification (e, Lepton identification (e, , , ))

Candidate events in 64 pb-1 Estimated background Acceptance efficiency

W e 10,461 (8.7± 2.4) % (5.2 ± 0.2) %

W W e e C Crossross S Sectionection in P in PluglugC

orf

u S

um

mer

Inst

itute

Corf

u S

um

mer

Inst

itute

Septe

mber

10 th

21

MT (GeV/c2)ET (GeV/c2)

Major systematics : PDFs, Amount of material in the simulation, Plug ET scale, Recoil modeling

QCD Z ℓ +ℓ− W

W W e e C Crossross S SectionectionC

orf

u S

um

mer

Inst

itute

Corf

u S

um

mer

Inst

itute

Septe

mber

10 th

22

BR(We) = 2.874 0.034stat 0.167sys 0.172lum nb

Working on an update of the measurement

• Bigger statistics ( ~ 220 pb-1)

• Much improved tracking efficiency

64 pb-1 sample

For comparison:

CDF - e (|| < 1.1) 2.782 0.014 + 0.167 (based on 72 pb-1)

CDF - (|| < 1.1) 2.772 0.016 + 0.166 (based on 72 pb-1)

+ 0.061- 0.056

+ 0.064- 0.060

W IW Identification in dentification in PPluglug R Regionegion

1.1 > > 2.8

(Electron energy corrected by offline corrections, Z vertex position and Ppr)

(Isorel corrected for leakage)

(corrected for Zvertex)

No PHOENIX electrons)No PHOENIX electrons)

• Match a track (PT > 1 GeV) such that track extrapolation to PES plane is

within a 3 cm window of PES cluster (|TrackX ,Y – PESX ,Y| < 3cm).

Electron selection requirements as in the W plug cross section (blessed 18/03/04).

Corf

u S

um

mer

Inst

itute

Corf

u S

um

mer

Inst

itute

Septe

mber

10 th

23