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Future Perspectives for Charm Physics at Hadron Machines

Future Perspectives for Charm Physics at Hadron Machines. Sandro De Cecco FNAL-PPD/CDF and INFN Roma 1. Outline:. Introduction on Heavy Flavour physics at hadron colliders. Charm production, charm as a probe for QCD Heavy quarks hadro-production in pp and NN interactions DD correlations

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Future Perspectives for Charm Physics at Hadron Machines

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  1. Future Perspectives for Charm Physicsat Hadron Machines Sandro De Cecco FNAL-PPD/CDF and INFN Roma 1 Sandro De Cecco - FNAL / INFN Roma

  2. Outline: • Introduction on Heavy Flavour physics at hadron colliders • Charm production, charm as a probe for QCD • Heavy quarks hadro-production in pp and NN interactions • DD correlations • Charmonium • Excited states, c-barions • Charm input to CP violation picture • D0 mixing • Direct CPV in Charm decays • FCNC decays • The Experimental “Charm” of Hadron Colliders Sandro De Cecco - FNAL / INFN Roma

  3. Heavy-Quark production in hadron collisions Leading Order and Next to Leading Order Q g Q g g g Flavor excitation radiative corrections Flavor creation Gluon splitting B/D-Hadrons and/or b/c-jets are the observables rather than b/c-quark Observed Proton structure Fragmentation NLO QCD Factorize physical observable into a calculable part and a non-calculable but universal piece Sandro De Cecco - FNAL / INFN Roma

  4. Fragmentation functions Db/c B/D Perturbative part: probability to find a hadron with fraction x’ of original parton momentum Hadronization: non perturbative QCD, need models Charm will have softer P-spectrum than b. Sandro De Cecco - FNAL / INFN Roma

  5. (-) s(pp→X) Tevatron SppS LHC 1mb s(bb) 1mb 1nb 1pb 0.001 0.01 0.1 1.0 10 102 √s (TeV) Charm and beauty at collider • Total inelastic x-sec ~100 mb • = 103-104 x s(cc/bb) • x-sec is 105-106 larger than at e+e- • Open spectrum of mesons and barions: • Bu , Bd , Bs , Bc , b , b… • D+, D0, Ds , c , cc , c… • Large cross section  • Select triggering on: • Semileptonic decays • Trigger m, e • Hadronic decays (CDF-SVT) • One or more displaced tracks i.e. large impact parameter Sandro De Cecco - FNAL / INFN Roma

  6. Lxy ~ 1 mm B/D decay Primary Vertex Secondary Vertex Impact Parameter( ~100mm) Selecting heavy flavour decays CLEO • To select charm and beauty • In hadronic environment: •  High resolution tracking • detector is mandatory • Only way to access hadronic decays is to trigger on tracks CDF Example: the CDFSecondary Vertex Trigger SVT • Online (L2) selection of displaced tracks • based on Silicon detector hits. D0 K Sandro De Cecco - FNAL / INFN Roma

  7. Charm program at hadronic machines Tevatron • First experiment doing high precision charm physics at collider, collecting huge yields in hadronic D modes • Many results already (in this talk) and more to come • Nice charm physics program mainly on rare FCNC and LFV rare decays ( see Frank Lenher talk ) • Relies on the presence of a muons to trigger charm • Expect to be able to select clean charm signals thanks to fine tracking and PID • Will measure cc x-sections in pp, pN and NN collisions LHC • Thinking about having a dedicated D* charm trigger selecting huge and clean samples of hadronic D modes • Will definitely take over what CDF started in the search for CPV and mixing in charm Sandro De Cecco - FNAL / INFN Roma

  8. Open cc Production Sandro De Cecco - FNAL / INFN Roma

  9. Prompt Charm Meson X-Section With very early CDF data: 5.80.3pb-1 ! • Measure prompt charm meson • production cross section • Data collected by SVT trigger • from 2/2002-3/2002 • Measurement is not statistics limited • Large and clean signals: Sandro De Cecco - FNAL / INFN Roma

  10. Separating prompt from secondary Charm Separate prompt and secondary charm based on their transverse impact parameter distribution. Prompt D Secondary D from B • Need to separate direct D and BD decay • Prompt D point back to collision point • I.P.= 0 • Secondary D does not point back to PV • I.P. 0 Prompt peak Detector I.P. resolution shape measured from data in K0s sample. BD tail D impact parameter Direct Charm Meson Fractions: D0: fD=86.4±0.4±3.5% D*+: fD=88.1±1.1±3.9% D+: fD=89.1±0.4±2.8% D+s: fD=77.3±3.8±2.1% Most of reconstructed mesons are prompt Sandro De Cecco - FNAL / INFN Roma

  11. Prompt Charm Meson X-Sections Determine trigger and reconstruction efficiency from data and MC Measure charm meson pT spectrum Integrated cross sections: As a comparison the beauty meson x-sec (CDF Run I): CDF prompt charm cross section result published in PRLhep-ex/0307080 Sandro De Cecco - FNAL / INFN Roma

  12. Differential Charm Meson X-Section D*+ D+ Ds D0 PT dependent x-sections: (as reference) Data/Theory PRL89:122003,2002 Theory prediction: Calculation from M. Cacciari and P.Nason: Resummed perturbative QCD (FONLL) JHEP 0309,006 (2003) Measured x-section is ~1.5 factor higher: similar to B+ Sandro De Cecco - FNAL / INFN Roma

  13. Open cc production future studies: • Studying cc correlations through angular difference Df. • Can separate contributions from different production mechanisms: • Flavour creation • Flavour Excitation • Gluon splitting • Issues are: • Low efficiency to have opposite charm in the acceptance • Backgrounds at low Df from BDDX decays. • CDF already has clean samples of D*-D0, D*-D+ and D*Ds consisting of ~ few 100’s / few 1000’s events depending on the modes. • Expect to have correlation results based on 1 fb-1 of Luminosity Df BDD BBbar Sandro De Cecco - FNAL / INFN Roma

  14. Charm as a probe in Pb-Pb collisions ( from C. Fabjan ) • Heavy quarks with momenta < 20–30 GeV/c  v << c • Gluon radiation is suppressed at angles < mQ/E • “dead-cone” effect • Due to destructive interference (inside cone gluon with v=c would violate causality) • Contributes to the harder fragmentation of heavy quarks and implies lower energy loss for heavy quarks relative to light quarks A.Dainese nucl-ex/0311004 D mesons quenching reduced Ratio D/hadrons (or D/p0) enhanced and sensitive to medium properties Yu.L.Dokshitzer and D.E.Kharzeev, Phys. Lett. B519 (2001) 199 [arXiv:hep-ph/0106202]. Sandro De Cecco - FNAL / INFN Roma

  15. Hadroniccharm selection Combine ALICE tracking + secondary vertex finding capabilities (sd0~60mm@1GeV/c pT) + large acceptance PID to detect processes asD0K-+ ~1 in acceptance / central event ~0.001/central event accepted after rec. and all cuts Results for 107 PbPb ev. (~ 1/2 a run) significance vs pT S/B+S ~ 37 S/B+S ~ 8 for 1<pT<2 GeV/c (~12 if K ID required) Sandro De Cecco - FNAL / INFN Roma

  16. mc PDFs scales pp, 14 TeV down to 1 GeV/c! down ~ 0! D0 Cross section measurement Pb-Pb Sandro De Cecco - FNAL / INFN Roma

  17. Charmonium Production Sandro De Cecco - FNAL / INFN Roma

  18. Inclusive J/yproduction CDF: Lower pT trigger threshold for : pT() ≥ 1.5 GeV J/y acceptance down to pT=0 0<pT<0.25 GeV D0: Larger acceptance for  total J/y production cross section at Tevatron is: D0: 4.8 pb-1 CDF: 39.7 pb-1 Sandro De Cecco - FNAL / INFN Roma

  19. Inclusive bcross section • Run I: b cross-section ~ 3x old NLO QCD • Theoretical approaches: new physics, Next-to-Leading-log resummations, non perturbative fragmentation function from LEP, new factorization schemes… • Experimentally: unbinned maximum likelihood fit to the flight path of the J/yin the R- plane to extract the b fraction Run II: Bottom Quark Production cross-section: PRD 71, 032001 (2005) Good agreement  Sandro De Cecco - FNAL / INFN Roma

  20. g + b/c x-section • Probes heavy flavor content of the proton and its PDF (also with Z0) • Experimental approach: • One isolated and High Etg (> 25 GeV) • One jet with a secondary vertex (b/c “like” jet) • Fit on the secondary vertex mass distribution of the tagged jets to separate b, c and light quarks g + c g+ b s(b + g) = 40.6 +/- 19.5 (stat.) + 7.4 -7.8 (sys.) pb s(c + g) = 486.2 +/- 152.9 (stat.) + 86.5 -90.9 (sys.) pb Sandro De Cecco - FNAL / INFN Roma

  21. Other charm states Sandro De Cecco - FNAL / INFN Roma

  22. excited D** states • Plenty of D**: Dj narrow, wide, radial, orbital, resonant, nonresonant… • Narrow states are the only widely observed objects so far… • HQET predicts splitting of states vs mQ • The large statistics of charm at CDF gives access to D** Sandro De Cecco - FNAL / INFN Roma

  23. D** Properties D1,2 D*+- D*+D0+ D0K-+ D2 D+- D+K+-- Prompt D1,2 • Huge sample of narrow D** resonances • Competitive in measuring prompt D** properties! • … and secondary from B’s Secondary D** Sandro De Cecco - FNAL / INFN Roma

  24. D** results High precision masses and widths from prompt D1,2 M(D1)=2421.7 0.7 0.6 MeV (D1)=20.0 1.7 1.3 MeV M(D2)=2463.3 0.6 0.8 MeV (D2)= 49.2 ±2.3 ±1.3 MeV Non-leptonic mass in BlXcwhere Xc is D** mass moments analysis mean r.m.s Probe HQET and contraints for CKM element Vcb Sandro De Cecco - FNAL / INFN Roma

  25. …charm et al. … c-Barions decaying in fully hadronic modes accessibles with SVT trigger and … X(3872) J/y pp M(pp) spectrum fraction from B: (16.0 ±4.9 ±1.0)% Sandro De Cecco - FNAL / INFN Roma

  26. Charm Rare Decays Sandro De Cecco - FNAL / INFN Roma

  27. Search for FCNC D0→mm • SM expectation BR~ 3∙10-13 • Best limit: <4.1∙10-6 90% CL, Beatrice/WA92,E771 • Enhanced in N.P. (R-Parity Violation Susy: ~3.5*10-6) • Experimental strategy CDF: • Events from two-track trigger using first 69pb-1 of data • To cancel acceptance effects normalize toD0→pp Result: BR(D0→mm)<2.4x10-6 at 90% CL Comment:muon fake rate will set limit (~10-6) Next:use full muon coverage, add statistics, explore electron modes (less coverage but lower fake rate)  also look atD+→pmm, D+→Kmm, D0→me and Ds … see Frank Lenher talk in this workshop for details Sandro De Cecco - FNAL / INFN Roma

  28. CP Violation and Mixing in neutral D Sandro De Cecco - FNAL / INFN Roma

  29. D0→h+h- direct CP Asymmetries and BR’s • Search for direct CP asymmetries where f is CP eigenstate (ex. K+K-,p+p-): • …in single Cabibbo suppressed modes (KK) • Almost null in Cabibbo allowed (Kp) •  Use D0Kp as normalization mode • Data collected by the SVT trigger with 123 pb-1 of int. Luminosity • Relative branching ratios: • G(D0→K+K-) / G(D0→Kp) • G(D0→p+p-) / G(D0→Kp) • G(D0→KK) / G(D0→pp)~2.8 (SM) • Candidates selected as: D*+/-→D0p • (unbiased tag of the D0 flavor) Normalization mode D0→Kp ~180kfrom D*+/-→ D0p Sandro De Cecco - FNAL / INFN Roma

  30. Direct ACP in Cabibbo suppressed D0 decays D0KK 16220 200 D0pp 7334 97 • Systematic dominated by tracking charge asymmetry, scales with statistics of control sample • KK channel suffers from partially reconstructed D background , would benefit from PID. • CDF yields prospects: 2MD* taggedD0Kp per 1 fb-1 • sACP ~ 10-3is achievable with full Tevatron run (4-9 fb-1) - at SM limit • issue will be if SVT trigger can cope with Lumi increase. Sandro De Cecco - FNAL / INFN Roma

  31. Mixing in the D0 system • D0 mixing receives x and y contributions • SM model expectations: • x and y : ~ 10-4 - 10-2 • (depending on the model) • Enhancements in x could be hint of New Physics • RSM ~ O(10-6) Sandro De Cecco - FNAL / INFN Roma

  32. Search for D0 mixing through DG Can search for DG comparing lifetime of CP eigenstate (D0→KK) and CP mixed state (D0→K): yCP  t(K)/t(KK) - 1 Best measurement at present from BaBar: syCP=0.006 yCP=0.034 0.0140.007 • CDF is currently performing D0  KK, pp, Kplifetime analysis • expect s(ct) < 2 mm (statistical only) • most of systematics cancel in the ratio, but: • Deconvolve SVT trigger bias at 1 mm level is a challenge • Nasty effect from secondary D0 from B’s Sandro De Cecco - FNAL / INFN Roma

  33. Direct Search for Mixing • Most sensitive method comes from looking for ‘Wrong Sign’ K pairs in D0 decays. • These occur directly through DCS decays. • Time dependent analysis can decouple contributions from: DCS • Direct DCS • Interference • Mixing D0K+ - D0 Mix (x’ and y’ because of possible strong phase difference between diagrams) Sandro De Cecco - FNAL / INFN Roma

  34. D0 Wrong Sign decays (time integrated analysis) • Almost 0.5 M Right Sign D*D0preconstructed in 350 pb-1 selected by SVT trigger • No PID so use of kinematics to reduce background from misreconstructed D0 Get the WS D* yield binning in D* mass difference  fit the signal NWS = 2005 ± 104 Sandro De Cecco - FNAL / INFN Roma

  35. D0 Wrong Sign rate results: Time integrated WS/RS ratio: Which in the limit of no mixing is: RWS:RS = RD = BR(D0K+p-)/BR(D0K-p+) • Results competitive with B-factories (CDF has x2 data on tape) • Next step:time dependent analysis and limit in the x’ y’ plane Sandro De Cecco - FNAL / INFN Roma

  36. LHC-b prospects for charm CPV and mixing ( from Guy Wilkinson and Frederic Teubert ) • Will implement a dedicated D* trigger stream: • Hadron trigger: displaced vertex +high PT tracks (4kHz). Expected compositionb:c~ 50%:20% • High level D*(D0hh)pselection “offline quality” (250Hz). Expect b:c ~ 36%:24% • In one year of running (107 s) at nominal luminosity (2·1032cm-2s-1): • Expect 250 - 500 M D*  D0pdecays with D0Kp channel, 102 x CDF ! • Raw estimates (based on signals statistics only) for sensitivity to charm CPV and mixing are: • s(ACP)[D0KK] ~ 10-4 normalizing to Kp mode • s(yCP) ~ 10-4in the lifetime difference analysis • s(x’) ~ 10-5 in mixing search through Wrong Sign' Kp signals LHC-b will possibly be sensitive in SM range, detailed studies on-going … Sandro De Cecco - FNAL / INFN Roma

  37. Summary • Charm production (cc and charmonium) is usefull test of QCD calculations to be tuned for precise background estimates in NP searches. • Already high precision results from Tevatron, to be explored at LHC. • A wide range of charmed hadrons are accessible at collider experiments, complementarity to e+e- • CDF demonstrates that is possible to perform high precision searches for charm CPV and mixing in hadronic modes D0hh • LHC-b will have 2 orders of magnitude more D0hh yields and will be very competitive in this field. • Huge CDF and D0 legacy of knowledge in doing Charm Physics at hadronic machines is left to next generation experiments. Sandro De Cecco - FNAL / INFN Roma

  38. Backup slides Sandro De Cecco - FNAL / INFN Roma

  39. Tevatron performances • CDF II has collected so far ~ 1.26 fb-1 out of 1.57 fb-1 delivered by Tevatron. • Record peak luminosity is ~1.8∙1032cm-2s-1 • Around 900 pb-1are availablefor Charm/Beauty physics (good tracking detector conditions) • Current analysesuse 180 - 350 pb-1 of integrated luminosity Sandro De Cecco - FNAL / INFN Roma

  40. The CDF II detector CDF Tracking System • Lepton ID • Particle ID • Muons:CMU, CMP, CMX (||<1.1) • dE/dX in COT • Electrons: CEM (EM calorimeter) • CPR (pre-shower detector) • Time Of Flight detector Sandro De Cecco - FNAL / INFN Roma

  41. COT track ( 2 parameters) 5 SVX coordinates Lxy ~ 1 mm B decay Primary Vertex Secondary Vertex Impact Parameter( ~100mm) beam spot d Impact Parameter (transverse projection) SVT: the CDF hadronic h.f. trigger • Online Impact parameter • Available at Level 2 trigger (20µs latency) • convolution of transverse size of the beam spot with the impact parameter resolution of the SVT: s≈47 mm ≈ 35mm + 30 mm SVT resolution Beam spot size Impact Parameter distribution Offline s ~ 45mm Sandro De Cecco - FNAL / INFN Roma

  42. B physics triggers at CDF II Conventional at colliders (Run I) With SVT trigger 2-Displaced tracks PT(trk) > 2 GeV 120 m < I.P.(trk) < 1mm SpT> 5.5 GeV fully hadronic modes 1-Displaced track + lepton (e, ) 120 m < I.P.(trk) < 1mm PT(lepton) > 4 GeV Semileptonic modes Di-Muon (J/) Pt() > 1.5 GeV J/ modes down to low Pt(J/)~0 (Run II) + Sandro De Cecco - FNAL / INFN Roma

  43. Study bb correlation B production x-section, Run I B cross section measured from Run I at Tevatron is consistently higher than NLO QCD Theoretical development still ongoing. Ex: fragmentation effect ……. Experimental Approaches: More cross section measurement -- energy at 1.96TeV -- lower pT(B)  Measure CHARM production cross section Sandro De Cecco - FNAL / INFN Roma

  44. Differential Charm Meson X-Section PT dependent x-sections: Theory prediction: CTEQ6M PDF Mc=1.5GeV, Fragmentation: ALEPH measurement Renorm. and fact. Scale: mT=(mc2+pT2)1/2 Theory uncertainty: scale factor 0.5-2.0 Calculation from M. Cacciari and P. Nason: Resummed perturbative QCD (FONLL) JHEP 0309,006 (2003) Sandro De Cecco - FNAL / INFN Roma

  45. Charmonium as probe for diffractive Higgs • Calibration signature: • exclusive D.P.E. production of cc • search for cc  J/y g •  Esclusive channel:p + p  p + H (bb) + p • Hexcl ~ 3 fb , signal / background ~ 3 @ LHC • then: MH= Mmiss = Sandro De Cecco - FNAL / INFN Roma

  46. Welcome back to Bc • Mode that gave the first evidence of the Bc (CDF Run I) • Large yield, no clean resonance though! 106 events 46.07.3 events • First signal of fully reconstructed Bc • Mass measurement on ~0.8 fb-1 ~ 39 signal candidates Sandro De Cecco - FNAL / INFN Roma Hep-ex/0505076

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