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Charm Results from FOCUS

Flavor Physics CP Violation 2004. October 4 -9, 2004. Charm Results from FOCUS. Kihyeon Cho Kyungpook National University Daegu, Korea (On behalf of FOCUS Collaborations). Contents. Why Charm Physics? FOCUS Experiment Recent Charm Results from FOCUS Pseudoscalar semileptonic decays

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Charm Results from FOCUS

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  1. Flavor Physics CP Violation 2004 October 4 -9, 2004 Charm Results from FOCUS Kihyeon Cho Kyungpook National University Daegu, Korea (On behalf of FOCUS Collaborations)

  2. Contents • Why Charm Physics? • FOCUS Experiment • Recent Charm Results from FOCUS • Pseudoscalar semileptonic decays • Vector semileptonic decays • Charm hadronic mixing • Search for new particles – pentaquarks, double charm baryons • Conclusions

  3. Why charm physics? • Window to new physics • Standard model rates for rare decays, CP violation and mixing are very low. • With current experiments, observation of CP violation, rare decays or mixing  new physics • Provides information about QCD • Measurements of production characteristics, lifetimes, branching ratios and subresonant analyses provide insight into QCD. • Needed for b physics • Many b particles decay to charm so branching ratios and lifetimes are needed for accurate b results. • Experimental techniques are developed in charm physics. (lifetime measurement, Dalitz plot analyses...) • Heavy quark effective theory often needs charm to bootstrap to b physics.

  4. FOCUS Experiment Photoproduction of Charm with an Upgraded Spectrometer Univ. of California-Davis, CBPF-Rio de Janeiro, CINVESTAV-Mexico City, Univ. Colorado-Boulder, FERMILAB, Laboratori Nazionali di Frascati, Univ. of Illinois-Urbana-Champaign, Indiana Univ.-Bloomington, Korea Univ.-Seoul, Kyungpook National Univ.-Daegu, INFN and Univ.-Milano, Univ. of North Carolina-Asheville, INFN and Univ.-Pavia, Univ. of Puerto Rico-Mayaguez, Univ. of South Carolina-Columbia, Univ. of Tennessee-Knoxville, Vanderbilt Univ.-Nashville, Univ. of Wisconsin-Madison ~100 Physicists, 18 institutes from 5 countries

  5. |primary vtx |secondary vtx BeO BeO Background Subtracted Golden Mode Charm tarsil Decays / 200 mm tarsil Vertexing is the Key Golden Modes: D+ K-p+ p+D0 K-p+D0 K-p+ p+ p-

  6. Pseudoscalar semileptonic decay • Using D0 p-m+n & D0 K-m+n • (D0 p-m+n) /(D0 K-m+n) • Pole masses • f-(0)/f+(0) • f+(0)/f+K(0) • Non-parametric q2 dependent

  7. Why Pseudoscalar semileptonic decay? • Hadronic current contains information about strong contributions. The differential decay rate is • Measuring the q2 dependence and form factors in heavy quark transition is critical to our understanding of QCD.

  8. What do we measure in D0Pln? f+(q2) parameter • (D0 p-m+n) /(D0 K-m+n) • Pole masses • f-(0)/f+(0) • f+(0)/f+K(0)  provides the test of SU(3) symmetry breaking • Non-parametric q2 dependent  A model independent measurement would allow to discriminate between different models. Pole form Modified pole from

  9. Fitting Technique on D0 p-m+n / K-m+n • Fit D*-D0 mass difference plot to find the amount of combinatoric background. • Apply the mass difference cut (< 0.154 GeV/c2) to suppress combinatoric and peaking background

  10. Results on D0 p-m+n / K-m+n 28829 • Fit to cos l and q2 to measure branching ratio, pole masses and the ratio f-(0)/f+(0). 6574  92 , (GeV/c2) Preliminary

  11. Extracting f+(0)/f+K(0) • Compute a numerical integration on Dalitz • Get efficiency as a function of q2 • Get yield from the fit • Using PDG • |Vcd/Vcs|2 =0.051  Consistent with the predictions from SU(3) symmetry breaking and lattice QCD Preliminary

  12. pen Ken form factor f+(q²) Based on 820 events Kln single-pole model pln single-pole model q² / GeV² Non-parametric q2 dependent Using ~13,000 K events f+(q²) Preliminary q² / GeV² Excellent agreement with LQCD! • 3 brand new results from CLEO, Belle and FOCUS on form factor f+(q²) inD0pln / Kln

  13. Summary for pseudoscalar semileptonic decay • The pmn and Kmn branching ratio is consistent with recent results from CLEO. • The pole masses are lower than the predicted value at the D* or Ds* masses. • We presented a non-parametric analysis of the q2 dependence for D0K which shows excellent agreement with the results obtained with the parametric analysis and lattice QCD. , (GeV/c2) Preliminary

  14. 2. Vector Semileptonic decay • D+ K*0 m+ n form factor • Branching ratio • D0 K*- m+ n form factor • Branching ratio

  15. Theory G(D+K*0m+n) / G(D+ K0m+n) Old quark model Use upstream Ks (~10%) so that both the signal (Kpmn) and normalization (Ksmn) leave 3 tracks in FOCUS microstrip S-wave corrected PLB 598 (2004) 33

  16. Form Factors of D0K*-+ • K*- Ks - • After background subtraction, we fit D*-D0 mass difference and cosl X cos v X q2 distribution at the same time. • Results • RV= 1.706  0.677  0.342 • R2 = 0.912 0.370  0.104  World’s first measurement Preliminary

  17. Summary of vector semilepotonic decay Preliminary PLB 598 (2004) 33

  18. 3. D0-D0 hadronic mixing and DCS decays • D0 goes to K+- in two ways (mixing + CF decay and DCS decay)  Interference • Assuming CP conservation, D0  K+- wrong sign to right sign decay ratio is written by • Three terms from DCS decays, interference & mixing • Soft pion charge in D*+  D0+ defines right sign(RS) and wrong sign(WS). • Fit for RDCS, x’2 and y’ Mixing parameters

  19. Right Sign vs Wrong Sign

  20. Summary for Mixing Results • All results shown here assume CP conservation. • FOCUS results agree better with BaBar in location and shape than CLEO.

  21. 4. New particle searches • S=-1 pentaquark (1540)+ with uudds • S=-2 pentaquark  (1860)–– with uddss • Charm pentaquark c(3100)0 with uuddc • Double charm baryons cc with ccu and ccd

  22. Evidence for +(uudds)

  23. Evidence for + (cont’d)

  24. (1540)+ p Ks search • No evidence for (1540)+ pKs but reconstructs 8 million K*(892)+ Ks+ and 240,000 (1385)+  0+

  25. (1860)– – search • (1860)- --- (S=-2 pentaquark) • NA49 shows evidence for (1860)- - and (1860)0 decaying -.. • No evidence for (1860)- --- but reconstructs 60,000 (1530)0 - +, approximately 1,000 times more than observing experiment.

  26. Charm Pentaquark search • No evidence for a charm pentaquark decaying to D*-p or D-p with a factor of 10 more D*+ decays than the observing experiment.

  27. CC search No evidence

  28. Summary for Search Results • No evidence for (1540)+ pKs but reconstructs 8 million K*(892)+ Ks+ and 240,000 (1385)+  0 • No evidence for (1860)- --- but reconstructs 60,000 (1530)0 - +, approximately 1,000 times more than observing experiment • No evidence for a charm pentaquark decaying to D*-p or D-p with a factor of 10 more D*+ decays than the observing experiment. • No evidence for double charm baryons with 10 times more C decays than the observing experiment.

  29. Conclusions • Charm physics gives a rich source of new results. • FOCUS is playing a major role in understanding the charm decays. • The recent charm results from FOCUS include • Charm pseudoscalar semileptonic decays • Charm vector semileptonic decays • Charm hadronic mixing • Search for pentaquarks and double charm. • FOCUS is continuing studies of charm physics. • Charm mode …

  30. Backups

  31. FOCUS Spectrometer At Fermilab g BeO charm g ~175 GeV • Segmented target • Silicon vertexing • MWPC tracking • Cenenkov ID • EM/hadronic Calorimeter • Muon detectors

  32. Kln 1.910.04 q2 dependent (cont’d) Clearly the data does not favor the simple Ds* pole • We presented a non-parameteric analysis of the q2 dependence for D0K which shows excellent agreement with the results obtained with the parameteric analysis and lattice QCD.

  33. D+ K*0 m+n channel • Only external diagram involved. • Factorization is possible between hadronic and leptonic current.

  34. D+ K*0 m+n decays Helicity FF are combinations of one vector and two axial form factors. Two observables parameterize the decay right-handed m+ Two amplitudes get summed over W polarization using D-matrices left-handed m+ H0(q2), H+(q2), H-(q2) are helicity-basis form factors computable by LQCD  Four body decays requires five variables: 3 angles, Mk , q .

  35. Interference in D+ K*0 m+n -15% F-B asymmetry! matches model Focus “K*” signal Yield 31,254 DataMC  Huge Asymmetry in cosv below K* pole led to a discovery of s-wave interference.

  36. K* interference term (Aei) Signal events weighted by avg(cosqV): No added term S-wave interference term PLB535(2002) 43

  37. Form Factors D+K*0l+n S-Wave effects apparent only with high statistics Lattice Gauge! • A=0.3300.0220.015GeV-1 •  =0.68  0.07  0.05 rad • RV= 1.5040.0570.039 • R2= 0.8750.0490.064 Models Experiment PLB544(2002) 89

  38. D0K*-+ channel

  39. K* interference term (Aei) • A term which is non-symmetric vs. cosv appears due to the S-wave • Use a model that includes S-wave •  = 0.68 rad fixed from •  A=0.3470.2220.053 GeV-1

  40. Branching Ratio • D*-D mass difference plot for normalization mode • Accounting for S-wave component in • Normalization mode  Excellent agreement with semielectronic decay

  41. Summary of vector semilepotonic decay Preliminary PLB 598 (2004) 33

  42. Fit Shape (Signal)

  43. Double charm baryon production compared • If the C+K-+ (CK-++) signal is real, SELEX produces at least 42 (111) times more cc baryons relative to C than FOCUS.

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