Transcript Document 7872695

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
DØ
Cross Section for
B+ Production
Cross Section for
b-Jet Production
A. Maciel
(NIU)
b Production Status
at pp Colliders
b Quark Production Measurements
• UA1 (540 GeV)
• DØ , CDF (1.8 TeV)
• UA1 , CDF , DØ (630 GeV)
All experiments are in
agreement with one another,
and find significant data
excess over theory
B Meson Production Measurements
• CDF (1.8 TeV) - same pattern
note: photoproduction also same pattern
Hera (e+ p) γ 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 Δφbb
XXXV Rencontres de Moriond, QCD & Hadronic Interactions, March 18-25, 2000
A. Maciel
(NIU)
b Quark Integrated Cross Section
( Data / Theory )
1.8TeV
.63TeV
XXXV Rencontres de Moriond, QCD & Hadronic Interactions, March 18-25, 2000
A. Maciel
(NIU)
Cross Section for
B+ Meson Production
CDF Collaboration
( Preliminary )
 an updated measurement of
B +  J/ψ K+ ; J/ψ  µ+µ–
XXXV Rencontres de Moriond
QCD and Hadronic Interactions
Les Arcs, France (March 18-25, 2000)
A. Maciel
(NIU)
CDF:
B +  J/ψ K+
J/ψ  µ+µ–
( both muons in SVX )
PT(K) > 1.25 GeV/c
PT(B) > 6.0 GeV/c
XXXV Rencontres de Moriond, QCD & Hadronic Interactions, March 18-25, 2000
A. Maciel
(NIU)
CDF:
B +  J/ψ K+
PT(B+) > 6 GeV/c
|y (B+) | < 1
Integrated σ(B+) = 3.51 ± 0.42(stat) ± 0.53(sys) μb
Theory (central values μ , mb , εP) is 1.54 μb
XXXV Rencontres de Moriond, QCD & Hadronic Interactions, March 18-25, 2000
A. Maciel
(NIU)
Cross Section for
b-Jet Production
DØ Collaboration
( Preliminary )
 introduction
 data selection
 inclusive spectrum
 b component
 tagging acceptance
 results
XXXV Rencontres de Moriond
QCD and Hadronic Interactions
Les Arcs, France (March 18-25, 2000)
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; dσ = dσ(open) + dΔ (clustering)
XXXV Rencontres de Moriond, QCD & Hadronic Interactions, March 18-25, 2000
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
|η|<1
= 2
2 B.R.
ΔσbJet A (ET)
FB(ET)
ΔNμJet

=
ΔET 2(B.R.) L ε(PTμ,ETJet) ΔET
TAG
XXXV Rencontres de Moriond, QCD & Hadronic Interactions, March 18-25, 2000
A. Maciel
(NIU)
Data Sample
Run-1B (5.2±0.3) pb–1 muon & jet trigger
muon PT > 4GeV Jet Tower > 3GeV
Offline Selection
Jets
Muons
ET > 25 GeV
PT > 6 GeV
| η | < 0.6
| η | < 0.8
ΔR = 0.7
ΔR < 0.7
Detection Efficiencies
Jet
Muon
Trigger
ET (85 - 100%)
PT (50 - 60%)*
Reco
100%
PT (90 - 95%)
Offline
(97±1)%
(83±3)%
(*) Includes geom. acceptance
XXXV Rencontres de Moriond, QCD & Hadronic Interactions, March 18-25, 2000
A. Maciel
(NIU)
Inclusive Spectrum
Muon-Tagged Jets
XXXV Rencontres de Moriond, QCD & Hadronic Interactions, March 18-25, 2000
A. Maciel
(NIU)
b Component
PTRel
PT µ
Jet
PTRel template
(b and non-b)
fits to data at
four ET ranges
XXXV Rencontres de Moriond, QCD & Hadronic Interactions, March 18-25, 2000
A. Maciel
(NIU)
b Component (jet ET)
Relative Uncertainty
χ2[2] = 0.96
Covariance Matrix
2.65
1.35
0.48
-0.01
1.45
1.52
1.56
2.22
2.67
x E-3
3.39
XXXV Rencontres de Moriond, QCD & Hadronic Interactions, March 18-25, 2000
A. Maciel
(NIU)
b-Jets Spectrum
b-Tagged Jets
XXXV Rencontres de Moriond, QCD & Hadronic Interactions, March 18-25, 2000
A. Maciel
(NIU)
Tagging Acceptance
Corrections due to;
• Muon η-range , pT-threshold
• Muon-Jet association; ΔR<0.7
• Unseen Jet-ET; ( μ + ν )
Correct observed spectrum
• B. R. b  μ X
with Monte Carlo ratio;
• Jet η-range
MC(bμ) parton jets, |η|<1
–1
A(ET) = MC(bμ) analysis image
XXXV Rencontres de Moriond, QCD & Hadronic Interactions, March 18-25, 2000
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
A. Maciel
(NIU)
Systematic Uncertainties
Summary
( relative , percentual , mostly correlated )
XXXV Rencontres de Moriond, QCD & Hadronic Interactions, March 18-25, 2000
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
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
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
XXXV Rencontres de Moriond, QCD & Hadronic Interactions, March 18-25, 2000