1 / 50

Nstars: Open Questions

Nstars: Open Questions. L. Tiator, Institut für Kernphysik, Universität Mainz. Introduction Roper and S 11 the role of the D 15 or P 11 pentaquark in eta production missing resonances in etaprime and kaon production Summary and Conclusion. MAID collaboration. Dieter Drechsel and L.T.

marty
Télécharger la présentation

Nstars: Open Questions

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. Nstars: Open Questions L. Tiator, Institut für Kernphysik, Universität Mainz • Introduction • Roper and S11 • the role of the D15 or P11 pentaquark in eta production • missing resonances in etaprime and kaon production • Summary and Conclusion

  2. MAID collaboration Dieter Drechsel and L.T. Institut für Kernphysik, Universität Mainz, Germany Sabit Kamalov Laboratory of Theoretical Physics, JINR, Dubna, Russia Wen-Tai Chiang and Shin Nan Yang (for h and h‘) Physics Department, National Taiwan University, Taipei, Taiwan Terry Mart (for K) Departemen Fisika, FMIPA, Universitas Indonesia, Depok, Indonesia

  3. What is a resonance? • a peak in the cross section

  4. What is a resonance? • a peak in the cross section • a peak in the imaginary part of a pw amplitude associated with a zero in the real part

  5. pw amplitudes of pion photoproduction S11 partial wave P33 partial wave W=1232 MeV W=1535 MeV it works for the D(1232) no zero crossing for S11(1535)

  6. What is a resonance? • a peak in the cross section • a peak in the imaginary part of a pw amplitude associated with a zero in the real part • a pole of the T-matrix in the 2nd Riemann sheet e.g. with speed-plots of pw amplitudes

  7. g,pArgand Diagrams and Speed-Plots

  8. What is the origin of a resonance? • a (qqq) bound or excited state with possible admixtures of (qqqg) or (qqq qq) etc. • a dynamically generated object of nucleon + meson interaction, e.g.:D33(1232)= N +p does not workP11(1440) = N + ppmay work well (e.g. Krewald et al)(but e.m. properties are not yet tested)S11(1535) = S + Kalso works in some cases (Waas, Weise, Kaiser)(cannot describe n/p ratio, also form factors would be a real test) • M. Lutz (GSI): all resonances, except D(1232), can be dynamically generated)

  9. How can resonances be tested? • mass, width, pole position and hadronic decay modes (branching ratios) in different channels • e.m. transition momentsor photon couplings • e.m. transition form factors

  10. 4 missing resonances in the gap 1800 MeV < W < 1900 MeV

  11. open questions forg,p • Roper and S11 resonances • photon couplings of most resonances are still quite inaccurate, even for 4-star • D13partial wave has ambigous solutions below the resonance

  12. comparison between MAID and SAID

  13. comparison between MAID and SAID SAID MAID

  14. comparison between MAID and SAID

  15. current situation with the P11 (Roper) multipoles W=1710 MeV W=1440 MeV

  16. CB proposal with MAMI C

  17. open questions for g,h • qqq resonances vs. dynamically generated resonances with ppN or with KS, e.g. S11(1535) • target asymmetry in S11/D13 region • exotic resonances: Does the Q+ pentaquark exist? if so, it should have a non-strange partner P11(~1700)

  18. Target Polarization Maid cannot describe the target polarization in the D13-S11 region below 800 MeV, but other models fail as well h-Maid 2001 data: Bonn 1998

  19. Target Polarization However, a fit is possible if a phase difference of ~90° is introduced between the D13(1520) and S11(1535) resonances. But this is impossible within an isobar model. (L. Tiator et al., Phys. Rev. C60 (1999) 035210) h-Maid 2001 model-independent fit data: Bonn 1998

  20. Comparison with preliminary data from CB-ELSA total c.s. on proton and neutron (I. Jaegle, priv. comm. 2006) h - Maid with a strong D15 resonance

  21. ETA - MAID 2003 reggeized isobar model (weak D15, bh = 0.7 %) standard isobar model (strong D15, bh = 17 %) (preliminary data from CB-ELSA, I. Jaegle, priv. comm. 2006) only the model with the strong D15 can describe the neutron data

  22. pentaquark solution

  23. open questions for g,h‘ • missing or misidentified resonances • we find S11(1904) and P13(1926) • role of the D13 resonance are there 2 resonances: D13(2080) as given in PDG and a D13(1940) as „seen“ in KL

  24. fit to preliminary g,h‘ data from JLab/CLAS (M. Dugger, N*2005 and private comm.) fit to SAPHIR 1998 data

  25. open questions for g,KL • how many resonances should be built in ? • do we really see “missing resonances” ? • data discrepancies between SAPHIR and CLAS are very disturbing • partial wave analysis in terms of multipoles is not yet possible due to imcomplete database

  26. p(g,K)Ltotal cross section in the second peak the D13 plays an important role

  27. which resonance is important? Dc2=(c2all-c2all-N*)/c2all D13 (2080) Resonances found in SAPHIR data analysis Resonances found in CLAS data analysis

  28. Fit 1 Fit 2 extracted multipoles Fit 3 Kaon-Maid

  29. Summary • nail down the Roper resonance in g,p • improve g,p database for D waves • solve puzzle of target asymmetry in g,hit will help to resolve the structure of the S11(1535) • clarify the situation with the P11 pentaquarkin g,h • good chance to find missing resonances in g,h‘S11(1905), P13(1925) • g,Kmay be the most difficult reaction to analyze (large background and many resonances) but probably also the first reaction for a complete experiment

  30. comparison of old h‘-Maid with SAPHIR(98) data only S11 resonance required P11 or even higher resonances are not really necessary

More Related