Heavy Flavour Production at D

1
Heavy Flavour Production at DØ
Daniela Bauer
Imperial College London
for the DØ collaboration
Hadron Collider Physics 2002
Karlsruhe 30/9-4/10 2002
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DØ Run II programme

• production cross section and angular
• correlations

• J/? cross section and polarization

• Y cross section

• Production and spectroscopy of B-mesons and
• baryons

• Lifetimes

• CP violation (SM and non-SM)

• CKM studies

• Bs mixing

• rare decays

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The upgraded D? detector
Muon Toroid
Calorimeter
Solenoid, Tracking System (CFT, SMT)
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DØ tracking system
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DØ - Muon detectors
Central region re-use Run I PDT new
scintillators for triggering
A-f Scint
PDTs
Forward Trigger Scint
new shielding for beampipe
Shielding
New forward system to replace Run I system mini
drift tubes scintillators for triggering
Forward Tracker (MDTs)
Bottom B/C Scint
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The DØ Trigger System

• Towers, Tracks, missing ET
• Some correls
• Single Sub-Dets
• Not quite deadtimeless

• Correlations
• Calibrated Data
• Physics Objects e,?,jets,?,missing ET

• Simple Reco
• Physics Algorithms

L3
L1
L2
50 Hz
1 kHz
5 kHz
Decision time 50ms
2.3 MHz
Decision time 100ms
Decision time 4.2ms
Current rates L1/L2/L3 500/200/50 Hz
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Run II Luminosity
most data used for commissioning
data used in analyses 5 pb-1
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b-quark production

• LO/NLO/NNLO
• QCD including

• flavour excitation

• gluon splitting

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Run I b-quark production cross-section
Differential b-jet cross-section
b production cross section as a function of
minimum pt
PRL 85, 5068 (2000)
Mangano, Nason, Ridolfi Peterson frag.
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Is there a significant excess in B-meson
production ?

• Binnewies, Kniehl, Kramer, hep-ph/9802231
• correct treatment of B fragmentation functions

• similar approach from Cacciari, Nason,
• hep-ph/0204025

• Frixione NNLO might explain differences
• ICHEP 2002

• Berger, hep-ph/0201229 SUSY

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Run II mujet cross section - preliminary
4.8 pb-1
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b-tagging at DØ
offline

• impact parameter

• secondary vertexing

trigger level

• impact parameter at Level 3

• Silicon Track Trigger (STT) at Level 2

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Tagging b-jets
µ
local muons only
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Tagging b-jets
di-muon sample
data
cc
bb
ptrel(µ2) (GeV)
ptrel(µ2) (GeV)
ptrel(µ2) (GeV)
ptrel(µ1) (GeV)
ptrel(µ1) (GeV)
ptrel(µ1) (GeV)
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Tagging b-jets impact parameter
track
jet axis
jet axis
dca
track
primary vtx
positive IP
negative IP
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Impact parameter tagging
impact parameter significance impact
parameter/sqrt(error2(primary vtx)error2(track))
sample
high
(b-enriched)
generic di-jet sample
background
impact parameter significance
impact parameter significance
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di-µ jet candidate
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Run I J/? production cross section
pt gt 8 GeV
2.5 ? ? ? 3.7
pt gt 5 GeV
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Run II J/? and Y signal

s(J/?) 88 3 MeV
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Run II J/? production cross section
N(J/?)
s(J/?)
L ekine ereco etrigger eaccept etrack-match
L Luminosity 4.8 pb-1
etrigger di-muon trigger.
ereco from scanning, muon system only
etrack-match muons matched to central track
ekine only simulate muons which reach muon
chamber
eaccept inactive material, etc.
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Run II J/? production cross section-preliminary
4.8 pb-1 of data

30 systematic uncertainty
region not measured in Run I
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Future measurements J/? polarization
CDF Run I
? angle(J/?lab,µJ/?) I(?) 3/2/(a3)
(1 a cos2 ?)
PRL 85, 2886(2000)
a (sT -2sL)/(sT 2sL)
CEM No polarization NRQCD transverse at
high pt
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J/? Polarization
? angle(J/?lab,µJ/?)
pt(J/?) gt 10 ?(J/?) lt 1.8 pt(µ) gt 2 ?(µ) lt 1.9
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Conclusions

• Improved muon and new tracking systems
• lower muon pt threshold, better
  resolution,
• lower systematics

• The detector is (mostly) working as planned.

• The first analyses are well under way.