QCD and EW Results at the Tevatron Collider

1
QCD and EW Results at the Tevatron Collider
THEN
NOW QCD _at_ Run I
Prospects for Run II EW Physics
Short change of many analyses!
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QCD in Run I
Jets
Inclusive cross sections and ratios pfd,
NLO QCD, scaling, Dijet Angular
Correlations/Mass compositeness
ShapesFragmenation hard
emission/shower development
Photons
Inclusive cross sections Exclusive ??, ?
charm, etc
Resummation/KT effects!
Hard Diffraction/DPE/Color Singlet Exchange
Models vs event characteristics and fits to
diffractive pdfs
3
Jet Cross sections vs Pseudorapidity
DØ
?d2?? dET d?? (fb/GeV)
Q2 (GeV2)
x
ET (GeV)
4
Jet CS vs. ? Quantitative comparisons to
predictions
Variations of correlation coefficients within the
range of their uncertainties give a similar
ordering of the ?2, hence a similar relative
preference of PDFs.
5
QCD in RunIIHigh PT reach
Run II 100 events ET gt 490 GeV 1K events ET gt
400 GeV Run I 16 Events ETgt 410 GeV Great
reach at high x and Q2, the place to look for
new physics!
Make point abt errors scaling, pdf improvements
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CTEQ5 pdfs
x-Q region spanned by experimental data in
CTEQ5 Tevatron jets in blue
Tevatron jet data serves as constraint in medium
x region
In RunII scale errors reduce w/ Gammajet stats.
for moderate to high PT jets offering significant
constraints on gs
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1800 GeV Photon Cross Section
DØ Central and Forward
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Diphotons
Photon Scaling
Resummed calc in good agreement with data
CDF Photons
DØ DiPhotons
Measure of soft emission effects
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Hard Diffraction at Run I
a.k.a. Hard CSE
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CDF Diffractive W, dijet and b-bbar at
sqrt(s)1800 GeV
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Double Pomeron_at_RunII w/ DØ/CDF upgrades
DØ Roman Pot Spectrometer complete w/ p/pbar arms
CDF Pots on anti-proton
side Beam shower counters mini-plug double
spectrometer proposal in works
DoublePom in RunII Valuable measure for
understanding structure/nature of these processes
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ElectroWeak (W/Z) Physics in Run I
W Bosons Detected

• Topics
• General Features of Production
• Inclusive Cross Section
• W Boson Width
• W Boson Mass Preliminaries
• W Boson Mass
• Trilinear Gauge Boson Couplings

Top is discussed in the talk by E. Barberis at
this conference
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Inclusive Cross Sections

• sB(W-gt l n) 2.2 nb
• sB(Z-gt l l-) 0.22 nb
• Cross section measurement uncertainty
• Stat Å Sys 2,
• Luminosity error 4
• Theory prediction uncertainty
• 3, NNLO, O(as2)
• Dominated by PDFs at NLO
• (need NNLO)

Luminosity L(D0) 1.062 x L(CDF) D0 uses world
avg. s(pp)inel, CDF uses CDF measurement
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General Features of WZ Production
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W Boson Width

• Indirect Method

• Direct Method (CDF)
• Model independent
• Study high-end tail of MT(ln).

(SM2.093 0.002)
Form ratio
SM EW
Perturbative QCD
LEP
CDFD0 combined
(LEP combined2.12 0.11)
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W Boson Mass

• Input from theorists calculations tuned by our
  measurements.

PT(W) Ladinsky-Yuan
Sampling of our published results
W Boson Production Decay Model
PDFs
D0 very recent
W Spin Orientation E. Mirkes. (1992)
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W Boson Mass

• W Mass measurements from
• MT(W) _at_ CDFD0
• PT(lepton) _at_ D0
• ET(n) _at_ D0
• Using
• electron channels _at_ CDFD0
• muon channels _at_ CDF

• Uncertainty example (CDF electrons)
• Statistical 65 MeV/c2
• Systematic 92 MeV/c2
• ET Scale 75 MeV/c2
• Detector resolution 25 MeV/c2
• PDFs 15 MeV/c2
• PT(W) 15 MeV/c2
• Recoil Model 37 MeV/c2
• Backgrounds 5 MeV/c2

• CDF (em) combined (2000)
• D0 Run 1 (e) Result (2000)

D0 CC electron channel
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Scaling of uncertainties
Systematics to attack
WGRAD
NLO Showering, etc
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W/Z Mass Ratio
Extraction of W Mass from W/Z M_T ratio
Stat
Sys
DØ Run 1a W Mass M_T 80.350 - 0.140 - 0.165
- 0.160 Ratio 80.160 - 0.360 - 0.075
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Hadronic Decays of W/Z
CDF studies of b b-bar mass resolution
2,000,000 low ET dijet triggers could yield a
200K W/Z-gt jj sample after cuts Yielding 0.5gev
mass uncertainty fit to W 1 check on jet escale
(as seen in toy MC studies) But of particular
interest is z-gtb-bbar
2e6 events-gt588 after cuts Vertex tagging event
energy profile Mz 90-2.4 20x the data -gt 1
accuracy on b-scale
Bbbar useful for improving mass resol
studies, Higgs!!!
Good stats for absolute b-jet scale in the energy
range we need for top!
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WWg and WWZ Couplings

• In Run 1
• Established the EW coupling of W to g and W to
  Z.
• The Wg and WW processes were observed. Candidate
  WZ events observed.
• Anomalous Coupling Limits Wg, WW, and
  combined WZ results from D0 (equal gZ
  couplings)
• Another set of relations among couplings

eng mng

• In 2 fb-1
• 2000 engmng events per exp.
• Observe radiation zero
• Sensitivity to anomalous couplings 2-3X better.

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ZZg, Zgg, and ZZZ Couplings

• Zphoton final state
• Tests ZZg and Zgg couplings
• ZZg and Zgg 0 in SM (no s-channel diagrams)

• Run 1 Limits on coupling parameters

At 95 CL
(Zgg coupling limits similar)

• In 2 fb-1 we expect
• 600 Zg events per experiment
• sensitivity to limits about 5X smaller
• Our first ZZZ limits (CDF observed ZZ candidate
  with 4 muons in 1995)

PRD 4/1/98
nng 14 pb-1 eeg mmg 110 pb-1
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Another prospect for RunII
The W cross section as a luminosity monitor
Exp uncertainties dominated by background
fraction and background uncertainty Calculated
Sigma_w most important, dominated by pdf
uncertainties
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Concluding Remarks
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Inclusive jet production at fixed center of mass
energy
( s 1.8 TeV and s 630 GeV)
Ö
Ö
ò
ò
1 DET Dh
d2s dET dh
dET dh

Njet DET Dh L
versus ET
DET ET bin size , Dh h bin size , Njet
jets in bin , L luminosity

• Cross section
• How well do we know the proton structure (pdfs
  f( x))?
• Are quarks composite structures?
• Ratios (reduce systematic uncertainty)
• Assess effect of scale assumptions
• Is NLO ( as 3 ) sufficient?

pdf ? Compositeness ?
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Jet CS vs. ? (Data-Theory)/Theory
CTEQ4HJ CTEQ4
MRSTg MRST
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DØ Single Diffractive Results
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Diffraction Summary
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W boson mass top mass Constrains Higgs mass
Run 1
Tevatron Averages M(top)174.3-5.1
GeV M(W)80.454-0.063
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Why we like transverse mass method
Lepton PT
Detector effects dominate
Trans. Mass
rely on detector knowledge instead of W_PT
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W Mass Summary
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M(W) vs M(top)

• In the Standard Model, MW and Mtop provide
  indirect measurement of MHiggs

(F.M.. Renard)
Expectations after Run IIa (world average)

• Combining LEP II, CDF and DØ results Run II could
  yield

Input Mw 80.385 ? 0.065 GeV/c2 Mtop174.3
? 5.1 GeV/c2