tevatron electroweak results and electroweak summary

Tevatron Electroweak ResultsTevatron Electroweak ResultsAnd Electroweak SummaryAnd Electroweak Summary

Sean Mattingly

Brown University

For the CDF and DZero Collaborations

XXIV Physics in Collision

Boston, MA

29 June 2004

Sean MattinglyXXIV PiC29 June 2004 2

W and Z production

Well understood event signatures– Leptonic decay modes avoid high jets backgrounds– Increase understanding of detector by studying W/Z production

Cross sections are relatively well known and high

– High statistics and clean event signatures precision measurements such as…

p

p

q’q W±

e,

p

p

qq Z0/

e+, +

e-, -

BR = ~10% BR = ~3%

( ) 0.25 nbZ BR ( ) 2.7 nb W BR

Electroweak Physics at the TevatronElectroweak Physics at the Tevatron


Tevatron Electroweak MeasurementsTevatron Electroweak MeasurementsW production

– Decays to e,, lepton universality– Charge asymmetry constrain PDFs– Transverse mass distribution direct W mass & width

– Constrain Higgs mass

Z production– Search for Z’ resonances– Forward-backward asymmetry sin2(w), quark couplings

Combined W/Z– Ratio of W/Z cross sections * BR indirect W width

Diboson production - WW/WZ/W/Z– Triple & quartic gauge couplings

W/Z/Diboson production are important backgrounds for top, Higgs and SUSY production


W/Z Event SignaturesW/Z Event Signatures

W production

?lM Can’t measure pZ of

80.425 0.034 GeVWM (LEP/TeV)

2( [1 cos( )])l miss l missT T TM E E

Z productione+,+

q

e-,-Hadronic Recoil

q

q’

e,Hadronic Recoil

q

2( ) 2( )l l l l l l l l

M p p E E p p ��

91.1876 0.0021 GeVZM (LEP)


DetectorsDetectors

= -1

= -2

Run II LuminosityTypically: ~6 x 1031 / cm2 sRecord: 8.5 x 1031 / cm2 sDelivered: ~570 pb-1

Recorded: ~400 pb-1 / expt~100K Zs, ~10M Ws /lept chan

Goal: 4.4 fb-1 by end FY 09

DZero Run II upgrades2T solenoid, inner trackingPreshower system/shieldingTrigger, DAQ

CDF Run II upgradesInner trackingForward calorimeterExtended systemTrigger, DAQ

CDF Analyses: 65-200 pb-1DZero Analyses: 42-162 pb-1


Analysis MethodsAnalysis MethodsTriggers

– Electrons: EM calorimeter– Muons: track + muon system

Electron ID– High ET isolated EM calorimeter cluster usually w/ track match

Muon ID– High ET isolated track matched to muon detector track or calorimeter MIP

Z candidates– 2 leptons w/ invariant mass consistent with Z mass

W candidates– 1 lepton & missing ET > 25 GeV

ID efficiencies measured in Z eventsPrimary backgrounds determined using data jet events


DZero: BR( ) 275 9 9 28 pbZ stat syst lumiee

5.55.4CDF: BR( ) 255.2 3.9 15.3 pbZ stat syst lumiee

*BR(Z *BR(Z ee) ee) Two electrons, ET > 25 GeV

– DZero: || < 1.1, CDF: full detector (1st EM central)

Small backgrounds from jets, Z ,(DY correction)DZero Run II Preliminary

BkgBkg+MC SignalData

No track matchL=42 pb-1


*BR(Z *BR(Z ))Two opposite charged muons, pT > 15-20 GeV

– CDF: || < 1.0, DZero ||< 1.8

Very small backgrounds : jets(b), Z, cosmics, (DY corr.)

7.06.2CDF: BR( ) 248.9 5.9 14.9 pbZ stat syst lumi

DZero: BR( ) 261.8 5.0 8.9 26.2 pbZ stat syst lumi


6156CDF Central: BR( ) 2782 14 167 pbstat syst lumiW e

*BR(W *BR(W e e))One electron, pT > 25 GeV, missing ET > 25 GeV

– DZero: || < 1.1, CDF: central & plug

Backgrounds: jets, W, Zee

Points: Background Subtracted DataHistogram: We MC

L=42 pb-1

DZero: BR( ) 2844 21 128 284 pbW stat syst lumie

CDF Plug: BR( ) 2874 34 167 172 pbstat syst lumiW e


*BR(W *BR(W ))One muon, pT > 20 GeV, missing ET > 20 GeV

– DZero: || < 1.6 (from initial lumi), CDF: || < 1.0

Backgrounds: Z, Wjets(b)

DZero: BR( ) 3226 128 100 322 pbW stat syst lumi 6460CDF: BR( ) 2772 16 166 pbstat syst lumiW

L=17 pb-1


CDF/DZero ComparisonCDF/DZero Comparison

Similar efficiencies and purities– CDF: Includes forward electrons– DZero: Includes farther forward muons

Channel # eventsPurity

(%)Luminosity Used (pb-1)

* A (%)

We CDF 48.0K 94.0 72 23.1

DZero 27.4K 95.7 41 18.4

W CDF 31.7K 90.0 72 14.4

DZero 8.3K 88.0 17 13.2

Zee CDF 4242 98.5 72 22.7

DZero 1139 98.3 41 9.97

Z CDF 1785 98.5 72 10.2

DZero 6126 98.9 117 16.4


W/Z Cross Sections SummaryW/Z Cross Sections Summary

Van Neerven, Matsuura

Van Neerven, Matsuura


Indirect W WidthIndirect W Width

CDF combined electron & muon channels

( ) ( ) ( )

( ) ( ) ( )W W

Z Z

BR Z W lR

BR Z ll W

Tree level NNLO QCD calc (Van Neerven)

PDG(LEP)

SM EWK Calculation

10.93 0.15 0.13Combined stat systR ( ) (10.93 0.21)%BR W ( ) 2.071 0.040 GeVW


Toward Higher PrecisionToward Higher PrecisionLuminosity error 10% 6.5%

– CDF and DZero use same luminosity constants

Added luminosity– Improved statistical errors– Smaller lepton ID systematics– Refined background estimates

Improved detector simulation– Energy scale (EM and Hadronic), detector geometry and material

description

PDFs– Using CTEQ6 and MRST sets w/ error sets

Combine CDF and DZero results– Tevatron Electroweak working group

– Standardized error reporting– Account for error correlations

– http://tevewwg.fnal.gov Use precision measurements in electroweak fits (see 2nd part of talk)


Physics with Physics with Zleptonic(1 pronghadronic

– Demonstrates visibility of resonances at the Tevatron– DZero: muonic decays + observe N 0, CDF: electronic decays

Visible Mass (GeV)

D0 Run II preliminary L=68 pb-1

CDF: BR( ) 242 48 26 15 pbZ stat syst lumi DZero: BR( ) 222 36 57 22 pbZ stat syst lum


Physics with Physics with (cont)(cont)WCDF)

– Trigger on track + missing ET

– Count tracks in 10o cone, veto on tracks in 30o cone– Reconstruct 0 with detectors at shower max

– Combined mass < M

– Backgrounds: W, We, Z, jets

BR( ) 2.62 0.07 0.21 0.16 pbstat syst lumiW


Forward-backward AsymmetryForward-backward Asymmetry

e− p

e+

p

)0(cos)0(cos

)0(cos)0(cos

fbA

Z/* e+e- (CDF)

– At Tevatron can measure at Z pole and above and below– Directly probes V-A, extract sin2W and u/d couplings to Z


W Charge AsymmetryW Charge AsymmetryWe (CDF)

– Up-type quarks carry more average momentum– W+ boosted in p direction, W- boosted in p direction– Charge asymmetry as function of rapidity constrains PDFs

– Cannot unambiguously determine W±’s direction (lost ) but e± direction carries W± direction information

– Measure charge asymmetry using e± rapidity– Higher ET e± more closely aligned with W ± direction

– Main constraints for forward rapidities– Ratio of u/d PDFs

( ) / ( ) /

( ) / ( ) /W

d W dy d W dyA

d W dy d W dy


W Charge Asymmetry (cont)W Charge Asymmetry (cont)

Select W events and identify charge

– 50 < MT < 100 GeV, no other EM object with ET > 25 GeV

– Use calorimeter seeded tracking with forward silicon to determine charge out to |det| < 2

– Charge mis-ID rate measured using Zee– < 1% for |det| < 1.5, < 4% farther

forward

– Backgrounds bias asymmetry toward zero– Zee, W subtracted using MC, jets

using data


Drell-Yan Invariant Mass SpectrumDrell-Yan Invariant Mass Spectrum

CDF/DZero Compare to Drell-Yan– Set limits on Z’, extra dimensions, etc.– Improve on Run I limits, test new models

Di-EM Mass (GeV)

95% CL, M(Z’/SM) > 780 GeV

95% CL, M(Z’/SM) > 735 GeV


Diboson ProductionDiboson Production

Tevatron collisions can produce W, Z, WW, WZ, ZZ– Probe the gauge structure of electroweak– Search for anomalous couplings

– Improve diboson modeling– Diboson production backgrounds in searches for new physics

Leptonic decay modes– Minimize jet backgrounds


Diboson Production: WDiboson Production: W

W(e/: Firstselect Wl events (CDF/DZero)– Add photon requirement: isolated EM, no track, shower max

– Photon ET > 7-8 GeV, lepton-photon R > 0.7, || < 1.1 – Backgrounds: W+jet, Z+, Z+jet, “leX”, W

Initial State Radiation Final State Radiation WW: Triple Gauge Coupling

D0 RunII preliminary W(e/)

L(e) = 162 pb-1

L() = 82 pb-1


Diboson Production: WDiboson Production: W Cross Sections Cross SectionsDZero ( ET > 8 GeV) CDF ( ET > 7 GeV)

We162 pb-1

W82 pb-1

W(e/)202 pb-1

W+jet 80.0 ± 7.4 30.1 ± 10.0 49.52 ± 14.95

Z+ 4.7 ± 2.0 22.37 ± 1.26

“leX” 3.7 ± 0.5 0.6 ± 0.6

W 3.4 ± 1.1 0.9 ± 0.3 3.23 ± 0.29

Total Bkg 87.1 ± 7.5 37 ± 10 75.12 ± 15.01

Total SM 142 ± 17 67 ± 13 255.63 ± 26.52

Data 146 77 259

*BR(l) 19.3 ± 2.7(stat) ± 6.1(sys) ± 1.2 (lumi) pb 19.7 ± 1.7(stat) ± 2.0(sys) ± 1.1(lumi) pb

Baur NLO 16.4 ± 0.4 pb 19.3 ± 1.3 pb


Initial State Radiation Final State Radiation ZZg: Triple Gauge Coupling

Diboson Production: ZDiboson Production: Z

Z(e/)(CDF)– Z selection + photon

– Photon ET > 7 GeV, R(l) > 0.7, || < 1.1

– Relative backgrounds smaller than for W– Main background: Z+jet

( )10

( )W

Z

BR

BR

( )3

( )W

Z

BR

BR


Diboson Production: ZDiboson Production: Z Cross Section Cross Section

CDF: Z(ee/)202 pb-1

Total Bkg 4.4 ± 1.3

Total SM 70.5 ± 4.0

Data 69

*BR(l) 5.3 ± 0.6(stat) ± 0.4(sys) ± 0.3(lumi) pb

Baur NLO 5.4 ± 0.4 pb


Diboson Production: WWDiboson Production: WWTwo analyses from CDF

– High purity: identify 2 leptons– High efficiency: identify 1 lepton + 1 isolated track– Backgrounds: DY, WZ/ZZ/W, Z, ttllX, fakes

HWW (CDF/DZero): See E. Nagy’s talk

Purity analysis– 2 high pT leptons

– Opposite sign

– Missing ET > 25 GeV

– Veto if any high ET jets

– Reject if dilepton mass near Z mass and (missing ET)/ (scalar summed ET) < 3


Diboson Production: WW (cont.)Diboson Production: WW (cont.) Efficiency analysis

– 1 high pT lepton + 1 isolated high pT track– Missing ET > 25 GeV– Veto if > 1 high ET jet– Reject (missing ET)/(scalar summed ET) < 5.5

CDF: Purity Analysis CDF: Efficiency Analysis

WW 11.3 ± 1.3 16.3 ± 0.4

DY 1.1 ± 0.4 1.8 ± 0.3

WZ+ZZ+W 1.8 ± 0.1 2.4 ± 0.1

Top 0.05 ± 0.02 1.8 ± 0.1

Fakes 1.1 ± 0.5 9.1 ± 0.8

Total Bkg 4.8 ± 0.7 15.1 ± 0.9

Total SM 16.1 ± 1.6 31.5 ± 1.0

Data 17 39

(WW) 14.2 ± 5.6 4.9 ± 1.6 ± 0.9 pb 19.4 ± 5.1 ± 3.5 ± 1.2 pb

NLO Ellis & Campbell: 12.5 ± 0.8 pb


ZZ/WZ Final StatesZZ/WZ Final States

Look for leptonic final states (CDF)– 2-4 high pT leptons in e and channels (194 pb-1)

– ZZllll or ll and WZlll

– Require one lepton pair to be consistent with Z mass

– 5.1 ± 0.7 expected– 4 observed

– 95% CL: (ZZ/WZ) < 13.8 pb-1

– SM (Ellis & Campbell) = 5.2 pb


Precision Electroweak Measurements Precision Electroweak Measurements And Electroweak Radiative CorrectionsAnd Electroweak Radiative Corrections

Large number of measurements from LEP, SLC and Tevatron – W mass/width (Tevatron, LEP-2)– Top quark mass (Tevatron)– Z-pole measurements (LEP, SLD)

– Z lineshape parameters– Polarized leptonic asymmetries– Heavy flavor asymmetries and branching fractions– Hadronic charge asymmetry

In the SM, each observable can be calculated/fit in terms of– had, s(MZ), MZ, MW, sin2W, Mtop, Mhiggs, etc…

– Higgs & top enter as ~1% radiative corrections

– LEP Electroweak Working Group– ZFITTER, TOPAZ0

}Recent and future updates


W Mass/WidthW Mass/Width

Tevatron W mass and width – From fits to MT spectrum

LEP-2 W mass and width – From reconstructing Ws– e+e-WWqqqq or qql

– Difference between two final states: mW = 22 ± 43 MeV


W Mass ProspectsW Mass Prospects

Final CDF/DZero Run I W mass 80.452 ± 0.059 GeV

} Errors decrease with larger Run II luminosity and Run II detector upgrades

} Run II measurements of W charge asymmetry and Z rapidity distribution

constrain PDF reduce PDF uncertainty

Run II uncertainty goal 40 MeV per experiment– ~25 MeV combined (TEVEWWG)


Top Quark MassTop Quark Mass

DZero update on Run 1 result– Mtop = 180.1 ± 5.3 GeV– ~15% smaller error than previous

Preliminary CDF Run 2 results– See talk by A. Hocker– Not yet included in fits

Expected Run 2 accuracy: 2.5 GeV


W and Top Mass in Electroweak FitW and Top Mass in Electroweak Fit

Z-pole measurements– Use fit to indirectly predict W/top

mass (LEP-1, SLD)

– Direct and indirect agree– Test of SM– Both favor lighter Higgs

(indirect)

(direct)

LEPEWWG


Electroweak Fit: Top MassElectroweak Fit: Top Mass

Predicted and measured Mtop in good agreement– Measurement uncertainty half of prediction uncertainty

LEPEWWG


Electroweak Fit: W MassElectroweak Fit: W Mass

Predicted and measured MW in agreement– Measured MW not yet as accurate as prediction– Combined CDF/DZero Run II W mass: expect ~similar accuracy to

prediction

LEPEWWG


Electroweak Fit: Higgs MassElectroweak Fit: Higgs Mass

Fit using high Q2 (LEP, SLC, Tevatron) data– Most likely MHiggs = 113 ± 62

42 GeV– MHiggs < 237 GeV (95% CL)

LEPEWWG A. Quadt

Year


Electroweak Fit: SummaryElectroweak Fit: Summary

Fit to all observables– 2/Ndof = 16.3/13

– Largest pull from b AFB

– 2.5 effect in opposite direction of next largest pull: Al(SLD)

– Accurately predicts low Q2 measurements

– Atomic parity violation– Moller scattering– NuTeV?

LEPEWWG


NuTeV’s ResultNuTeV’s Result Paschos-Wolfenstein relation: neutrinos on isoscalar target

sin2W = 0.22773 ± 0.00135(stat) ± 0.00093(syst) [SM = 0.2226 ± 0.0004]

Or…assuming sin2W is in agreement (i.e. MW/MZ)– = 0.988 ± 0.004

3 effect– New physics? New particles, oscillations, etc…– Old physics? PDFs, non-isoscalar target, sea asymmetry, etc…

21 sinNC NCud W

CC CC

q qW±/Z


ConclusionConclusion

Many Tevatron Run II electroweak measurements– Detector understanding increasing– ~200pb-1 of luminosity analyzed per experiment– Preliminary W mass measurements soon

– TEVEWWG will combine CDF and DZero measurements

Standard Model describes large number of measurements with precision– Discrepancies can be interpreted as statistical fluctuations– Higgs mass constrained < 237 GeV, most likely MHiggs = 113 ± 62

42 GeV– Upcoming Tevatron Run 2 top quark and W mass measurements important

components in Higgs mass constraints

tevatron electroweak results and electroweak summary

Documents

dzero h

muon detector track

tevatron w

z eventsprimary backgrounds

wz production cross

dzero analyses

em central small backgrounds

detector geometry