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

1. Picture of FNAL or Oxford • • Charm Meson Pair Production • • Studies of Charmonium Production • - J/ and ' polarization • - Relative cc1, cc2 Production Charm Studies at CDF Burkard C. Reisert for the CDF Collaboration

2. Motivation:Inclusive Charm Meson Cross Sections CDF Run II (L=5.8 pb-1) CDF Run II (L=5.8 pb-1) (L=5.8 pb-1) FONLL D0 Cacciari et al., JHEP, 05:00, 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

3. Heavy Quark Production: Leading Order Picture • 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 PS = Parton Shower

4. 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

5. 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 ithPT bin Nij: Number of observed charm meson pairs with D1 in ithPT bin and D2 in jthPT 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

6. Inclusive triggered charm mesons

7. Number of D0TrigD*±Probe Pairs 2dim SB-subtraction by weighting events In mass plane of Trigger D and soft p tagged Probe D0

8. Number of D0TrigD*±Probe Pairs 2dim SB-subtraction by weighting events In mass plane of Trigger D and soft p tagged Probe D0

9. Ds+D*- D+D*- D*+D*-

10. Charm Meson Pairs vs. Df (Raw Yields) D+D*- 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)

11. Extraction of Prompt D Production • Extract prompt/secondary fractions from Ip of probe side D0: fbb =34% • Cross checks : Ip, Lxy of trigger/probe D and DD*- pair Prompt D PV = Primary Vertex Secondary D Ip

12. 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*+

13. D0D*- Pair Cross Section binned in PT(Trig) Error: statsys(fb) Common Syst. Error: • ~15%

14. 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)

15. D+D*- Pair Cross Section binned in PT(Trig) Error: statsys(fb) Common Syst. Error: • ~19% Significant shape discrepancy Consistent for D0D*- and D+D*-

16. Charmonium Production

17. p Color Singlet & Color Octet models soft g p 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 (>90%) J/y production (CDF Run I finds 30%) • PT spectrum does not match data c c J/y J/y c c p hard g p 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

18. p p P P P P P P P P J/y p “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

19. Polarization of J/y q* angle between m+ in J/y rest frame and J/y in lab frame a polarization parameter a=0 all 3 helicity states are equally populated  MC polarization templates (trigger efficiency from data)

20. J/y Yields and Separation of Prompt and Secondary J/y J/y selection Central: |y|<0.6 5<PT<30GeV/c Use m+m-combined impact parameter significance to separate prompt S≤8 and secondary S>16

21. Polarization of J/y Mesons • Polarization of J/y from B decays • independent of PT • aB = -0.066±0.050 • Consistent with BaBar • (aB = -0.129±0.009) • CDF result includes Bs and B baryons • Polarization of prompt J/y • Corrected for residual secondary J/y • a<0: longitudinal polarization

22. 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

23. y’ Polarization Results • Polarization in B decays • First measurement of aB for y’ • aB = 0.28±0.27± 0.03 • (consistent with J/y within stat.) • Polarization of prompt y’ • Longitudinal polarization at high pT, just as for J/y

24. 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 1.0±0.3 are consistent with most models.

25. e e m m J/y g ccJ 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 L=1fb-1)

26. ccJ Data Set • Here we reconstruct: • ccJJ/yg, J/ym+m-, ge+e- • 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

27. Results ons(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 < pT(ccJ) < 20 GeV/c • Color Octet predicts 5/3 (counting of Spin states)

28. Conclusion The unprecedented integrated luminosity delivered by the Tevatron in conjunction with CDF’s 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

29. Acknowledgements Contact persons for the presented CDF analyses: • Charm meson pair cross Sections Burkard Reisert, reisert@fnal.gov • J/y and y’ polarization Min-Jeong Kim mjkim@fnal.gov Kwangzoo Chung kchung@andrew.cmu.edu • Relative cc1cc2 production Patrick Lukens ptl@fnal.gov

30. Backup slides • Tevatron, CDF & Trigger

33. 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)

34. Tevatron New world record ISR @ √s=62 GeV • Run II Physics Goals: • Properties of top quark • Precision Electroweak Physics • CKM, Bs Mixing • Searches for new phenomena • Tests of QCD

35. 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 1.0<||<2.0 Time-of-Flight Drift Chamber Silicon Microstrip Tracker

36. 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 (>200 CPUs) L3 farm Full event reconstruction The trigger is the key to heavy flavour physics at hadron colliders 100 Hz L3 accept disk/tape

37. Secondary Vertex Decay Length Lxy Primary Vertex d=impact parameter Triggers forBeauty & Charm Physics Two Track Trigger PT(trk)>2 GeV IP(trk) >100 mm Fully hadronic modes Displaced track(s) + lepton (e, m) IP(trk)>120 mm PT(lepton) >4GeV Semileptonic modes Di-Muon (J/y) PT(m) > 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,dJ/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