Charm Studies at CDF

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• Charm Studies at CDF
• Burkard C. Reisert
• for the CDF Collaboration

Picture of FNAL or Oxford
Charm Meson Pair Production Studies of
Charmonium Production - J/? and ?'
polarization - Relative cc1, cc2 Production
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MotivationInclusive Charm Meson Cross Sections
(L5.8 pb-1)
CDF Run II (L5.8 pb-1)
CDF Run II (L5.8 pb-1)
FONLL
D0
Cacciari et al., JHEP, 0500, 1998
CDF Collab., PRL 241804

• The measurement of inclusive charm meson\cross
  sections (D0, D, D, Ds) was one of the first
  CDF Run II results
• up to a factor 2 higher than expected
• progress in theory reduced deviation
  - still on the high side
• measurement systematically limited

Kniehl et al., hep-ph/0508129
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Heavy Quark Production Leading Order Picture
PS Parton Shower

• Second charm particle in the event gives access
  to the underlying production mechanism
• Study fully reconstructed prompt charm meson
  pairs allows for acceptance and efficiency
  correction

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Charm Meson Pair Reconstruction

• Simple experimental approach
• Find triggered charm meson D0,
  D, D, Ds,
• Look for second charm meson probe D
• Take advantage of inclusive measurement from a
  short well controlled running period
• Measure of pair cross section relative to
  inclusive cross section, systematic uncertainties
  largely cancel over the entire CDF Run II

Primary Vertex
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Prompt Charm Production Cross Sections

• Inclusive production (already measured by CDF)
• Pair production
• Relative pair Cross section
• uses

Ni Number of observed charm mesons in ith PT
bin Nij Number of observed charm meson pairs
with D1 in ith PT bin and D2 in jth PT bin
fPD fraction of prompt D mesons fPDD fraction
of prompt pairs ei trigger and reconstruction
efficiency eij pair trigger and reconstruction
efficiency ej probe-side reconstruction
efficiency ??dt integrated luminosity B
branching fraction e.g. D0?Kp
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Inclusive triggered charm mesons
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Number of D0TrigDProbe Pairs
2dim SB-subtraction by weighting events In mass
plane of Trigger D and soft p tagged Probe D0
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Number of D0TrigDProbe Pairs
2dim SB-subtraction by weighting events In mass
plane of Trigger D and soft p tagged Probe D0
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DsD-
DD-
DD-
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Charm Meson Pairs vs. Df (Raw Yields)
DD-
D0D-
D0D-
D0D-
Uncorrected for efficiency (e) and secondary (fb)
detector level Df distributions fully
reconstructed decays of both D ? correct for e
(simulation verified on data)
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Extraction of Prompt D Production
Prompt D

• Extract prompt/secondary fractions from Ip of
  probe side D0 fbb 34
• Cross checks Ip, Lxy of trigger/probe D and
  DD- pair

PV Primary Vertex
Secondary D
Ip
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Measurement of Charm Meson Pair Cross Section
published CDF measurements of inclusive cross
sections
DD Pair yields and Prompt fraction
branching fraction from PDG
Inclusive Charm Meson Yields and prompt
Fractions
Efficiency for fully reconstructed Probe side
D
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D0D- Pair Cross Section binned in PT(Trig)

• Error
• stat?sys(fb)
• Common
• Syst. Error
• 15

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D0D- Cross Section

• Normalization of D0D- cross section in Pythia
  is about right,
• Gluon Splitting as important as Flavour Creation
• Pythia under estimates GS (over estimates FC)

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DD- Pair Cross Section binned in PT(Trig)

• Error
• stat?sys(fb)
• Common
• Syst. Error
• 19

Significant shape discrepancy Consistent for
D0D- and DD-
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Charmonium Production
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Color Singlet Color Octet models
soft g
p
c
c
J/y
J/y
c
c
p
p
hard g

• Color Singlet Model
• cc pair is bleached by radiating off a hard
  gluon
• Underestimates J/y (1/10) and
• y (1/50) production
• Feed down from ccj dominates (gt90) J/y
  production
• (CDF Run I finds 30)
• PT spectrum does not match data

• Non relativistic QCD introduces
• Color Octet Mechanism
• Soft gluon radiation
• Adjustable hadronization parameter allows to
  match the observed PT spectra and production
  cross sections
• Predicts transverse polarization for J/y,
  deviates from data

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Pomeronic Idea
Pomeron picture
pQCD

• Recent idea by V.A. Khoze, A.D. Martin, M.G.
  Ryskin and W.J. Sterling hep-ph/0410020
• Fusion of a symmetric colour octet state and a
  gluon
• Cross sections calculated in LO pQCD
  consistent with data
• PT spectra match data
• Predicts longitudinal polarisation of J/y
  increasing with pT

J/y
p
Emission of omerons omerons have vacuum
Quantum numbers JP 00
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Polarization of J/y

• q angle between m in J/y rest frame and J/y in
  lab frame
• a polarization parameter
• a0 all 3 helicity states are equally populated
• ? MC polarization templates
• (trigger efficiency from data)

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J/y Yields and Separation of Prompt and
Secondary J/y
J/y selection Central ylt0.6 5ltPTlt30GeV/c
Use mm- combined impact parameter significance
to separate prompt S8 and secondary Sgt16
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Polarization of J/y Mesons

• Polarization of J/y from B decays
• independent of PT
• aB -0.0660.050
• Consistent with BaBar
• (aB -0.1290.009)
• CDF result includes Bs and B baryons

• Polarization of prompt J/y
• Corrected for residual secondary J/y
• alt0 longitudinal polarization

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y Polarization

• Same theoretical framework applies to prompt y
  and J/y production
• no contribution from feed down from higher states
  therefore y is a cleaner system to test direct
  charmonium production
• y uses analysis approach as just described for
  J/y

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y Polarization Results

• Polarization in B decays
• First measurement of aB for y
• aB 0.280.27 0.03
• (consistent with J/y within stat.)

• Polarization of prompt y
• Longitudinal polarization at high pT, just as for
  J/y

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ccJ Production

• Models of prompt charmonium production in hadron
  collisions always contain significant ccJ
  contributions
• The measurement of s(cc2)/ s(cc1) has been
  performed at several energies and beam types over
  the years.
• Best measurements have 100 events, 30
  statistical uncertainty on the cross section
  ratio.
• Results like 1.00.3 are consistent with most
  models.

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Measurement of s(cc2)/s(cc1)

• Measurement of properties of ccJ production has
  always been an experimental challenge
• Low energy photon from ccJ?J/yg is difficult to
  measure (400 MeV in ccJ rest frame)
• Calorimeter measurements have good efficiency
  but poor resolution and high background in a
  hadron collider environment
• Conversion measurement
• - good resolution
• - poor efficiency
• (now compensated L1fb-1)

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ccJ Data Set

• Here we reconstruct
• ccJ?J/yg, J/y?mm-, g?ee-
• J/y selection as polarization analysis
• Photon conversion gives excellent energy (mass)
  resolution.
• Prompt and B-decays are easily separated
• Simultaneous fit to the mass and flight
• distance distributions is used to extract
• the relative yields for both prompt ccJ
• and ccJ from B decays

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Results on s(cc1)/s(cc2)

• New level of precision for measurement of
  s(cc1)/s(cc2)
• Should provide nice constraint on models of
  production mechanisms
• Result for prompt ccJ

for 4 lt pT(ccJ) lt 20 GeV/c

• Color Octet predicts 5/3 (counting of Spin
  states)

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Conclusion

• The unprecedented integrated luminosity delivered
  by the
• Tevatron in conjunction with CDFs high bandwidth
  trigger
• allows us to perform Charm studies we did not
  anticipate.
• New Charming results
• First measurement of charm meson pair cross
  section in an hadron collider
  environment probes open charm production ?gluon
  splitting underestimated
• Polarization measurements of J/y and y
  instigates new theory approach to
  charmonium production
• New level of precision for measurement of
  s(cc1)/s(cc2) provides new trial to models of
  charmonium production
• Charm Physics at the Tevatron has its beauty

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Acknowledgements

• Contact persons for the presented CDF analyses
• Charm meson pair cross Sections
• Burkard Reisert, reisert_at_fnal.gov
• J/y and y polarization
• Min-Jeong Kim mjkim_at_fnal.gov
• Kwangzoo Chung kchung_at_andrew.cmu.edu
• Relative cc1 cc2 production
• Patrick Lukens ptl_at_fnal.gov

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Backup slides

• Tevatron, CDF Trigger

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Heavy Quark Production in Higher Orders

• Example Feynman Diagrams
• Calculations with massive quarks
• incoming charm (?)
• charm in final
• state parton shower (?)
• All shown example graphs can be interpreted as
  higher order flavor creation

Flavor Creation (a2s)
Flavor Creation (a2s)
Flavor Excitation (a3s)
Gluon Splitting (a3s)
Gluon Radiation (a3s)
Gluon Radiation (a3s)
Interference Term (a4s)
Interference Term (a4s)
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Tevatron
New world record
ISR _at_ vs62 GeV

• Run II Physics Goals
• Properties of top quark
• Precision Electroweak Physics
• CKM, Bs Mixing
• Searches for new phenomena
• Tests of QCD

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Collider Detector at Fermilab
Muon System
New
Old
Central Calorimeter
Partially New
Solenoid
Fwd Calorimeter
? to 5.5
Muon
Plug Calorimeter
Scint based ? to 3.6
1.0lt?lt2.0
Time-of-Flight
Drift Chamber
Silicon Microstrip Tracker
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CDF Trigger DAQ System
CDF Detector
Hardware tracking for pT ?1.5 GeV
1.7 MHz crossing rate
Muon-track matching
42 L1 buffers
Dedicated hardware
Electron-track matching
L1 trigger
Missing ET, sum-ET
25 kHz L1 accept
Silicon tracking
Hardware CPU
4 L2 buffers
Jet finding
L2 trigger
Refined electron/photon finding
500 Hz L2 accept
Refined Muon-track matching
Linux farm (gt200 CPUs)
L3 farm
Full event reconstruction
The trigger is the key to heavy flavour physics
at hadron colliders
100 Hz L3 accept
disk/tape
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Triggers forBeauty Charm Physics
Two Track Trigger PT(trk)gt2 GeV IP(trk) gt100
mm Fully hadronic modes
Displaced track(s) lepton (e, m) IP(trk)gt120
mm PT(lepton) gt4GeV Semileptonic modes

• Di-Muon (J/y)
• PT(m) gt 1.5 GeV
• J/y, y(2S) modes
• Down to low PT(J/y)
• ( 0 GeV)

• Bs mixing (semileptonic)
• Tagging, lifetime

• y(2s), X(3872)? J/ypp (quarkonia)
• Bs?J/yf, Bu,d J/yKs() Lb?J/yL (masses,
  lifetimes, mixing calibration)
• Bs,d?mm (rare decays)
• Bc(lifetime B?J/ylX, mass B? J/yp)

• 2-body charmless decays (B0,Bs,Lb)
• Bs mixing (hadronic)
• Charm physics
• - inclusive cross sections
• - D0?Kp,pp,KK
• Heavy quark production