1 / 43

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

piper
Télécharger la présentation

Charm Results from FOCUS

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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.

More Related