Penn CDF Group Overview

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Penn CDF Group Overview B Physics Activities

• Joseph Kroll

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Contributions to the Experiment

• COT read out electronics and operation
• includes dE/dx calibration Eiko Yu (GS), Dave
  Ambrose (PD),
• Joel Heinrich (staff)
• contributions to tracking software Peter
  Wittich (PD)
• Dave Ambrose is COT co-subproject leader
• anticipate placing Aafke Kraan (PD) here
• TOF electronics and operation
• includes extensive work on calibration,
  reconstruction, physics
• Denys Usynin (GS) redid simulation and carries
  pager
• Matthew Jones (PD) moved to tenure track faculty
  position at Purdue
• Calorimeter calibration electronics
• Andrew Kovalev (GS) and Brig Williams

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Contributions to the Experiment (cont)

• Trigger Level 2 decision crate upgrade see
  talk
• responsible for back-end of system including
  trigger decision
• initial leadership from Peter Wittich
• Daniel Whiteson (PD) Kristian Hahn (GS) now
  driving back-end effort help from Paul Keener
  (staff) here
• Chris Neu (PD) shares responsibility for reCES
  part of system
• Trigger system
• P. Wittich L2 software coordinator then trigger
  subproject co-leader
• On-line beam profile monitoring with SVT see
  talk
• Chris Neu working with Luciano Ristori (CDF
  co-spokesperson)

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Contributions to the Experiment (cont)

• Leadership in operations
• Nigel Lockyer was operations department co-head
  from 2000-2002
• D. Ambrose M. Jones served 6 month terms as
  operations managers
• P. Wittich was Trigger subproject co-leader
• M. Jones is TOF subproject co-leader
• D. Ambrose is COT subproject co-leader
• Evelyn Thomson chaired the Run IIb XFT upgrade
  review
• aside all post-docs and grad. students serving
  as ACEs.
• Penn Group has made major contributions to
  operations of the experiment.

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Physics

• CDF physics effort organized in 5 groups
• top, electroweak, exotics, bottom, QCD
• Penn CDF group involved in several key areas
• top physics dilepton lepton jets channels
• cross section analysis
• mass measurement
• study of top decays for new physics
• Electroweak physics
• WW production measurement
• Exotic physics
• SUSY searches with dileptons
• B physics
• Bs flavor oscillations
• ?b branching fractions

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Physics (continued)

• Leadership roles
• Nigel Lockyer was co-spokesperson from June02 to
  June04
• Evelyn Thomson is top group co-convener
• Dave Ambrose co-led the Jet Simulation Task Force
• Daniel Whiteson is Monte Carlo coordinator for
  the top group
• Peter Wittich is Exotics group SUSY subgroup
  co-convener
• Joseph Kroll is Mixing Analysis co-coordinator
  for the B group
• J. Kroll was co-chair of the Higgs Sensitivity
  Committee
• Joel Heinrich is a member of the CDF statistics
  committee
• We are chairs of several godparent committees
  (internal review committees for publications)

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Physics Publications
The Penn CDF group has been the primary author or
has made major contributions to several Run II
publications
Charm meson production cross-section 1st
Tevatron Run II PRL (published)
top cross-section from dilepton events 1st CDF
high pT paper (accepted by PRL)
top cross-section lepton jets with kinematics
PRD in preparation
WW cross-section PRL in preparation
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The Beauty Unitary Triangle
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Neutral B Meson Flavor Oscillations
Flavor oscillations occur through 2nd order weak
interactions
e.g.
Same diagrams and formula for ?ms for Bs except
replace d with s
From measurement of ?md derive VtbVtd2
All factors known well except bag factor
decay constant
?md 0.489 0.008 ps-1 (2) (PDG
2002)
from Lattice QCD calculations see hep-ph/0406184
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B Meson Flavor Oscillations (cont)
If we measure ?ms then we would know the ratio
?ms/?md
Many theoretical quantities cancel in this ratio,
we are left with
from Lattice QCD calculations see hep-ph/0406184
This is why ?ms is high priority in Run II
Since Vts ¼ Vcb this gives us our side Rt
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Experimental Steps for Measuring Bs Mixing
1. Extract B0s signal decay mode must identify
b-flavor at decay (TTT)
Examples
2. Measure decay time (t) in B rest frame (L
distance travelled) (L00)
3. Determine b-flavor at production flavor
tagging (TOF)
unmixed means production and decay flavor are
the same
mixed means flavor at production opposite
flavor at decay
Flavor tag quantified by dilution D 1 2w, w
mistag probability
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Measuring Bs Mixing (cont.)
4. Measure asymmetry
Asymmetry is conceptual actually perform
likelihood fit to expected unmixed and mixed
distributions
Measure ?md to validate procedure
these formulas assume perfect resolution for t
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B Flavor Tagging
We quantify performance with efficiency ? and
dilution D
? fraction of signal with flavor tag
D 1-2w, w probability that tag is incorrect
(mistag)
Statistical error ?A on asymmetry A (N is number
of signal)
statistical error scales with ?D2
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Two Types of Flavor Tags
Opposite side
Applicable to both B0 and B0s
- other b not always in the acceptance
Same side
Based on fragmentation tracks or B
better acceptance for frag. tracks than opp.
side b
- Results for B and B0 not applicable to B0s
Reminder for limit on ?ms must know D
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Same Side Flavor Tags
Based on correlation between charge of
fragmentation particle and flavor of b in B meson
Decay of P-wave mesons B also contributes to
B0, B (not B0s)
Expected correlations different for B, B0, B0s
TOF
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Penn Contribution to CDF B Mixing Effort

• We are focusing our activities in 2 areas
• B flavor identification
• developed 1st Run II flavor tag (opposite side
  muons from b!?)
• required understanding sample composition of
  leptonSVT data, used by all members of the B
  group studying opposite side flavor tags
• currently pursuing understanding same-side kaon
  tagging
• 1st step is to measure rate of kaons around B,
  B0, B0s (thesis of D.Usynin) using both dE/dx
  and TOF for kaon identification
• crucial for reliable prediction of dilution
  need for limit on ?ms
• B Mixing coordination
• expect Aart Heijboer to join this analysis effort

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Soft Muon B Flavor Tag
Based on b!? of 2nd B hadron
Larger pTrel increases b!? suppresses b! c!?,
fakes
B
pTrel
?
pTrel
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Measure Kaon Multiplicity around Bs
Can we see a difference in K multiplicity around
B0, B, B0s?
Example Bs! Ds?? candidates
dE/dx
TOF
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Need Reliable Simulation of TOF
Example TOF resolution agreement between data
and MC
Data
MC
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B Baryon Branching Fractions
Thesis Shin Shan Yu
At present Tevatron is the unique accelerator to
study B Baryons
Current World average ?b lifetime lower than
expected
Compare semileptonic rates to hadronic rates for
?b
Use same trigger (two track hadronic) to cancel
trigger efficiencies
Check with topologically similar B meson decays
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B Baryon Signals
Semileptonic decay mode
Hadronic decay mode
?c signal
Unknown B baryon production fraction cancels in
ratio ?(B ! D??) ?(?b ! ?c??) ? can determine
absolute BFs