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N – N* Form Factors from the MAID Analysis

N – N* Form Factors from the MAID Analysis. Introduction: Inelastic electron scattering The unitary isobar model MAID and our analysis techniques Transition Form Factors N – D form factors at low and high Q2 N – Roper form factors and comparison with JLab analysis

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N – N* Form Factors from the MAID Analysis

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  1. N–N* Form Factorsfromthe MAID Analysis Introduction: Inelastic electron scattering The unitary isobar model MAID and our analysis techniques Transition Form Factors N – D form factors at low and high Q2 N – Roper form factors and comparison with JLab analysis detailed results for: D13(1520), S11(1535), F15(1680) some results for: S11(1650), D15(1675), P13(1720) Comparison with the naive non-relativistic quark model Summary and Conclusions L. Tiator Johannes Gutenberg-Universität Mainz in collaboration with D. Drechsel (Mainz) and S. Kamalov (Dubna)

  2. Inclusive Cross Section for Real and Virtual Photo Absorption

  3. Inelastic Electron Scattering in the Resonance Region

  4. in general: • transition form factors can only be obtained by • partial wave analysis • and background / resonance separation

  5. Definition of the N-N* Form Factors reduced multipoles:

  6. in our MAID analysistheresonancesaredressed dressing and undressing can be studied in Dynamical Models: e.g. Kamalov, Yang, Drechsel, L.T. and Sato, Lee, Julia-Diaz in most cases quark models calculate the bare resonance couplings a direct comparison with exp. analysis is not possible, e.g. Giannini on the hypercentral quark model

  7. partial wave analysis with resonance and background separation for helicity amplitudes and transition form factors we need the imaginary parts of the resonance multipoles

  8. data base for pion electroproduction data in the D region up to W = 1.3 GeV data up to the 3rd resonance region up to W = 1.7 GeV

  9. data base for pion electroproduction older data from SAID data base up W = 2 GeV

  10. E/M and S/M ratios for the ND transition analysis analysis the analyses are based on p0 data from JLab, Mainz, Bonn and Bates

  11. new Mainz08 analysis also uses preliminary JLab data from Villano et al • REM remains small and negative • RSM becomes much flatter around ~ 10%

  12. fit A fit B Ji, Ma, Yuan, PRL 90, 2003 pQCD with angular momentum effects

  13. Nucleon -> Delta on theLattice dynamical fermions – mp down to 360 MeV C. Alexandrou et al., 2008 GM : main problems at small Q² REM, RSM : in agreement within large uncertainties

  14. transition form factorsoftheRoper comparison of MAID and JLab analysis A1/2 MAID07 analysis with p0 data of Joo et al, 2002 Ungaro et al, 2006 S1/2

  15. transition form factorsoftheRoper comparison of MAID and JLab analysis A1/2 JLab analysis with p+ data of Joo et al, 2004 Park et al, 2007 S1/2

  16. transition form factorsoftheRoper comparison of MAID and JLab analysis A1/2 results from: Maid07 JLab and new Maid analysis with Park data S1/2

  17. Nucleon-Roper Transition Form Factors on the Lattice ~ S1/2 ~ A1/2 Huey-Wen Lin, ECT* Trento 2008 details and update tomorrow on this workshop!

  18. Transverse Charge Densities of the Nucleon and N -> Roper (in collaboration with Marc Vanderhaeghen)

  19. Updated Form Factors for higher Resonances • comparison with: • Maid2003 (EPJ A17, 2003, 357) • Maid2007 (EPJ A34, 2007, 69) • very recent (2008)with K. Park p+ data included in our database

  20. some changes for the D13, no change for the F15

  21. no changes for the S11 resonances

  22. here the new p+ data make some considerable difference

  23. Comparison with the naive non-relativistic quark model

  24. Summary and Conclusions • the GM form factor of the D(1232) can be extracted directly from the inelastic cross section with high accuracy • all other electric, magnetic and charge form factors can only be extracted from partial wave analysis • mostly due to JLab data on p(e,e´p0)p we could extract reliable ffs of             

  25. recent JLab data on p(e,e´p+)n help to remove correlations between partial waves, e.g. between P33 and P11 large effects also for D15 and P13 • longitudinal form factors can be best analyzed with the L-T interference cross section dsLT/dWas in the Hall A experiment at Q²= 1 and backward angles if possible more of such kind of exp. should be done in the future • the database for the neutron is very limited our analysis is based on 890 data points from 1971-1988 and most of our neutron ffs are not very conclusivenew data are needed on d(e,e´p-p)n

  26. Form Factors in the Electroproduction Process

  27. Form Factors in MAID2007

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