b Production

1
b Production at the Tevatron
Arthur Maciel Northern Illinois University for
the DØ and CDF collaborations
XXXV Rencontres de Moriond QCD and Hadronic
Interactions Les Arcs, France (March 18-25, 2000)
Two New Results
CDF
Cross Section for B Production
DØ
Cross Section for b-Jet Production
2
A. Maciel (NIU)
b Production Status at pp Colliders
b Quark Production Measurements
All experiments are in agreement with one
another, and find significant data excess over
theory

• UA1 (540 GeV)
• DØ , CDF (1.8 TeV)
• UA1 , CDF , DØ (630 GeV)

B Meson Production Measurements

• CDF (1.8 TeV) - same pattern

note photoproduction also same pattern Hera (e
p) ? p ? b b X (H1 ZEUS)
b Production Theory

• Recent report (G. Ridolfi at Fermilab b-Wshop, 10
  / 99)
• resummation of log(PT/MQ) - no significant
  improvement
• fragmentation treatment revisited -
  enhancement 10
• intrinsic kT2 of incoming partons - no
  significant changes,
• and worsens (flattens) angular
  correlations ?fbb

XXXV Rencontres de Moriond, QCD Hadronic
Interactions, March 18-25, 2000
3
A. Maciel (NIU)
b Quark Integrated Cross Section ( Data / Theory )
1.8TeV
.63TeV
XXXV Rencontres de Moriond, QCD Hadronic
Interactions, March 18-25, 2000
4
A. Maciel (NIU)
Cross Section for B Meson Production
CDF Collaboration ( Preliminary )

• an updated measurement of

B ? J/? K J/? ? µµ
XXXV Rencontres de Moriond QCD and Hadronic
Interactions Les Arcs, France (March 18-25, 2000)
5
A. Maciel (NIU)
CDF B ? J/? K J/? ? µµ
( both muons in SVX )
PT(K) gt 1.25 GeV/c PT(B) gt 6.0 GeV/c
XXXV Rencontres de Moriond, QCD Hadronic
Interactions, March 18-25, 2000
6
A. Maciel (NIU)
CDF B ? J/? K
PT(B) gt 6 GeV/c y (B) lt 1
Integrated s(B) 3.51 0.42(stat) 0.53(sys)
µb Theory (central values µ , mb , eP) is 1.54
µb
XXXV Rencontres de Moriond, QCD Hadronic
Interactions, March 18-25, 2000
7
A. Maciel (NIU)
Cross Section for b-Jet Production
DØ Collaboration ( Preliminary )

• introduction
• inclusive spectrum
• tagging acceptance

• data selection
• b component
• results

XXXV Rencontres de Moriond QCD and Hadronic
Interactions Les Arcs, France (March 18-25, 2000)
8
A. Maciel (NIU)
Introduction (Theory)

• Jets are more QCD-friendly (than quarks)
• Integrate away fragmentation details
• (Jet Et is regardless of b-mom. fraction)
• Jets are collinear-safe objects
• ( theory avoids resummation of large
• logarithms from hard collinear gluons )

S. Frixione, M. Mangano, Nucl.Phys. B483, 321
(1997)

• QCD production of jets containing heavy quarks
• LO bJets and bQuarks have identical spectra
• NLO amplitudes have 3-parton final states
• Loosely MNR(1992) Snowmass Jet-Cone
• at partonic level ds ds(open) d?
  (clustering)

XXXV Rencontres de Moriond, QCD Hadronic
Interactions, March 18-25, 2000
9
A. Maciel (NIU)
Introduction (Experiment)

• b-Jets are jets carrying b-flavor
• A new DØ look into b-production
• complementary to open b-quark studies
• Jets are directly observable
• Less model dependence in connecting
• observation with theory
• Access to differential cross sections
• Jet counting (muon tagged jets)
• theory counts jets with b ( b-integrated)
• DØ counts tagging muons (in jets)
• µ µ b b
• 2 B.R. 2

? lt 1
?sbJet ATAG(ET) FB(ET) ?NµJet ?ET
2(B.R.) L e(PTµ,ETJet) ?ET

XXXV Rencontres de Moriond, QCD Hadronic
Interactions, March 18-25, 2000
10
A. Maciel (NIU)
Data Sample
Run-1B (5.20.3) pb1 muon jet trigger muon
PT gt 4GeV Jet Tower gt 3GeV
Offline Selection
Jets Muons
ET gt 25 GeV PT gt 6 GeV
? lt 0.6 ? lt 0.8
?R 0.7 ?R lt 0.7
30K events
Detection Efficiencies
Jet Muon
Trigger ET (85 - 100) PT (50 - 60)
Reco 100 PT (90 - 95)
Offline (971) (833)
() Includes geom. acceptance
XXXV Rencontres de Moriond, QCD Hadronic
Interactions, March 18-25, 2000
11
A. Maciel (NIU)
Inclusive Spectrum
Muon-Tagged Jets
XXXV Rencontres de Moriond, QCD Hadronic
Interactions, March 18-25, 2000
12
A. Maciel (NIU)
b Component
PTRel
PTRel template (b and non-b) fits to data at
four ET ranges
PTµ
Jet
XXXV Rencontres de Moriond, QCD Hadronic
Interactions, March 18-25, 2000
13
A. Maciel (NIU)
b Component (jet ET)
Relative Uncertainty
?22 0.96
Covariance Matrix
2.65 1.35 0.48 -0.01
1.45 1.52 1.56
2.22 2.67
3.39
x E-3
XXXV Rencontres de Moriond, QCD Hadronic
Interactions, March 18-25, 2000
14
A. Maciel (NIU)
b-Jets Spectrum
b-Tagged Jets
XXXV Rencontres de Moriond, QCD Hadronic
Interactions, March 18-25, 2000
15
A. Maciel (NIU)
Tagging Acceptance

• Corrections due to
• Muon ?-range , pT-threshold
• Muon-Jet association ?Rlt0.7
• Unseen Jet-ET ( µ ? )
• B. R. b ? µ X
• Jet ?-range

Correct observed spectrum with Monte Carlo
ratio MC(b?µ) parton jets, ?lt1 MC(b?µ)
analysis image
A(ET)1
XXXV Rencontres de Moriond, QCD Hadronic
Interactions, March 18-25, 2000
16
A. Maciel (NIU)
b-Jets Cross Section
() 2 µO ... µO/2 , µO (ET2 Mb2)1/2
XXXV Rencontres de Moriond, QCD Hadronic
Interactions, March 18-25, 2000
17
A. Maciel (NIU)
Systematic Uncertainties Summary
( relative , percentual , mostly correlated )
XXXV Rencontres de Moriond, QCD Hadronic
Interactions, March 18-25, 2000
18
A. Maciel (NIU)
(Data-Theory) / Theory
Systematic errors and their correlations confer
80 probability to theory upper edge
XXXV Rencontres de Moriond, QCD Hadronic
Interactions, March 18-25, 2000
19
A. Maciel (NIU)
b-Quark Integrated Cross Section
()
() 2 µO ... µO/2 , µO (PbT2 Mb2)1/2
XXXV Rencontres de Moriond, QCD Hadronic
Interactions, March 18-25, 2000
20
A. Maciel (NIU)
Conclusion
Different experiments, and also different
measurements within each experiment, all confirm
a pattern for b production where data shows
normalization excess over theory (NLO - pQCD)
New DØ measurement suggests data-theory
convergence at higher transverse momenta
Tevatron Run-II (March 2001) should revisit
/confirm this trend
Thanks !
XXXV Rencontres de Moriond, QCD Hadronic
Interactions, March 18-25, 2000