PowerPoint Presentation

1W and Z Production at the Tevatron: Recent Results and Prospects

Terry Wyatt

Particle Physics GroupUniversity of Manchester

on behalf of the CDF and D collaborations 1OverviewIntroduction:Tevatron, detectors and integrated luminosityZ and W production and detectionMotivation for precise measurementsRecent resultsZ transverse momentum New for this conferenceZ, 1 fb-1, DZ transverse momentum using * New for this conferenceZee & Z, 7.3 fb-1, DZ cross section and rapidity New for winter 2010 conferencesZee, 2.2 fb-1, CDFW charge asymmetry New for winter 2010 conferencesWe, 1 fb-1, CDF re-analysis in terms of lepton AFB allowing direct comparison withW, 4.9 fb-1, DZ forward-backward asymmetry New for winter 2010 conferencesZee, 4.1 fb-1, CDF N.B. W mass measurements covered elsewhereProspects

223The Fermilab Tevatron Collider1992-95 Run I: Ldt ~ 0.1 fb-1, 1.8 TeV

Major accelerator/detector upgrades2002-11 Run II: Ldt ~ 9 fb-1 delivered, 1.96 TeV Ldt ~ 12 fb-1 expected by 2011 Further running 2012-2014? - being considered

Main Injector& Recycler(new for Run II)TevatronDCDFChicago_p sourceBooster

CDFD34Integrated Luminosity HistoryAverage data taking efficiency since 2002 is 84% (CDF) and 89% (D)

45CDF D

D = -ln(tan/2)

56CDF D

CDF detector highlightLarge volume, high precision, charged particle tracker 9-layer silicon tracker96-layer drift chamber1.4 m outer radius = -ln(tan/2)

D detector highlightHigh acceptance, low background, muon system0.5 m outer radius for D central tracker!67Producing W and Z in ppProton is a composite objectPDFs (Parton Distribution Functions) mll2 = x1x2sgluon bremsstrahlung x1,2 = eymll /s

Select ~ 106 tagged Wl and ~ 105 Zl +l events per fb-1

Z+ -

p_p_78Signatures of W and Z Production at the TevatronZ l+l-: pair of charged leptons:high pTisolatedopposite-chargepeak in l+l- invariant mass

Z e+e-

89Signatures of W and Z Production at the TevatronZ l+l-: pair of charged leptons:high pTisolatedopposite-chargepeak in l+l- invariant mass

W l : single charged lepton:high pTisolatedETmiss (from )cannot measure longitudinal peak in transverse mass

910Signatures of W and Z Production at the TevatronWl : single charged lepton:high pTisolatedETmiss (from )cannot measure longitudinal peak in transverse mass

10Why bother?Electroweak production Leptonic final statesHigh statistics samplesLow backgrounds

Precise measurements!

Clean probe of QCD and EW interactionsEssential to tie standard processes down before claiming discoverieseither at the Tevatron or the LHC11

Z transverse momentumZ, 1 fb-1, DUnfold pTZ resolution

For pTZ < 30 GeVsyst ~ 5%dominated by pT resolution systematicscf. stat ~ 1%Restricts choice of bin widthsHave such measurements reached the end of the road?12

Data-MC agreementStudy of pTZ using a novel methodaT less susceptible to detector resolution and efficiency variations than pTZaT/mll even less susceptible to detector resolution* aT/mll measured using only the directions of the leptons and thus very well measured13

ZStudy of pTZ using a novel methodZee, Z; 7.3 fb-1, D966,000 events with 70 < mll < 110 GeVCompare corrected data to ResBos with and without small-x broadening [Nadolsky, et al, Phys. Rev. D 64,114011 (2001)] |y|