NN –– N* Form Factors N* Form Factors from the MAID Analysisfrom the MAID Analysis

Introduction: Inelastic electron scattering

The unitary isobar model MAID and our analysis techniques

Transition Form Factors

a)N – form factors at low and high Q2

b)N – Roper form factors and comparison with JLab analysis

c)detailed results for: D13(1520), S11(1535), F15(1680)

d)some results for: S11(1650), D15(1675), P13(1720)

Comparison with the naive non-relativistic quark model

Summary and Conclusions

L. TiatorJohannes Gutenberg-Universität Mainz

in collaboration withD. Drechsel (Mainz) and S. Kamalov (Dubna)

Inclusive Cross Section for Real and Virtual Photo AbsorptionInclusive Cross Section for Real and Virtual Photo Absorption

Inelastic Electron Scattering in the Resonance Region Inelastic Electron Scattering in the Resonance Region

in general:in general:

transition form factors can only be obtained transition form factors can only be obtained byby

• partial wave analysis

• and background / resonance separation

Definition of the N-N* Form Factors Definition of the N-N* Form Factors

reducedmultipoles:

reducedmultipoles:

in our MAID analysis the resonances are dressedin our MAID analysis the resonances are dressed

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

partial wave analysispartial wave analysis

with resonance and background separationwith resonance and background separation

for helicity amplitudes and transition form factorswe need the imaginary parts of the resonance multipoles

data base for pion electroproductiondata base for pion electroproduction

data in the region up to W = 1.3 GeV

data up to the 3rd resonance region up to W = 1.7 GeV

JLab/Hall C Frolov 1999 p0 Q² = 2.5 - 4.3 GeV²

Bates Mertz et al. 2001 p0 Q² = 0.127 GeV²

Mainz Pospischil et al. 2001 p0 Q² = 0.127 GeV²

Bonn Bantes, Gothe 2002 p0 Q² = 0.6 GeV²

Mainz Elsner et al. / Stave et al.

2006 p0 Q² = 0.05-0.2 GeV²

JLab/Hall A Kelly et al. 2007 n0 Q² = 1.0 GeV²

JLab/CLAS Villano et al. 2008 prelim. p0 Q² = 6.0 – 7.9 GeV²

JLab/CLAS Joo et al. 2002 / 2003 p0 Q² = 0.4 – 1.8 GeV²

JLab/CLAS Joo et al. 2004 n+ Q² = 0.4 - 0.65 GeV²

JLab/Hall A Laveissiere et al. 2004 n0 Q² = 1.0 GeV²

JLab/CLAS Egiyan et al. 2006 n+ Q² = 0.3 – 0.6 GeV²

JLab/CLAS Ungaro et al. 2006 p0 Q² = 3.0 – 6.0 GeV²

JLab/CLAS Park et al. 2008 n+ Q² = 1.7 – 4.5 GeV²

data base for pion electroproductiondata base for pion electroproduction

older data from SAID data base up W = 2 GeV

DESY, DNPL, BONN … 1971 - 1999 p0 Q² = 0.1 – 4.3 GeV²

DESY, DNPL, BONN … 1973 - 1999 n+ Q² = 0.1 – 4.4 GeV²

DNPL, … 1971 - 1988 p- Q² = 0.5 – 1.4 GeV²

E/M and S/M ratios for the E/M and S/M ratios for the NN transition transition

analysisanalysis

analysisanalysis

the analyses are based on 0 data from JLab, Mainz, Bonn and Batesthe analyses are based on 0 data from JLab, Mainz, Bonn and Bates

new Mainz08 analysis also uses preliminary JLab data from Villano et alnew Mainz08 analysis also uses preliminary JLab data from Villano et al

1) REM remains small and negative

2) RSM becomes much flatter around ~ 10%

1) REM remains small and negative

2) RSM becomes much flatter around ~ 10%

fit Afit A

fit Bfit B

Ji, Ma, Yuan, PRL 90, 2003Ji, Ma, Yuan, PRL 90, 2003

pQCD with angular momentum effectspQCD with angular momentum effects

Nucleon -> Delta on the LatticeNucleon -> Delta on the Lattice

C. Alexandrou et al., 2008dynamical fermions – m down to 360 MeVdynamical fermions – m down to 360 MeV

GM : main problems at small Q²GM : main problems at small Q²

REM, RSM : in agreement within large uncertainties

REM, RSM : in agreement within large uncertainties

transition form factors of the Ropertransition form factors of the Roper

comparison of MAID and JLab analysis

A1/2

S1/2

MAID07 analysiswith 0 data ofJoo et al, 2002Ungaro et al, 2006

MAID07 analysiswith 0 data ofJoo et al, 2002Ungaro et al, 2006

transition form factors of the Ropertransition form factors of the Roper

comparison of MAID and JLab analysis

A1/2

S1/2

JLab analysis

with + data ofJoo et al, 2004Park et al, 2007

JLab analysis

with + data ofJoo et al, 2004Park et al, 2007

transition form factors of the Ropertransition form factors of the Roper

comparison of MAID and JLab analysis

A1/2

S1/2

results from:Maid07JLabandnew Maid analysis with Park data

results from:Maid07JLabandnew Maid analysis with Park data

~ A1/2

~ S1/2

Huey-Wen Lin, ECT* Trento 2008details and update tomorrow on this workshop!

Huey-Wen Lin, ECT* Trento 2008details and update tomorrow on this workshop!

Nucleon-Roper Transition Form Factors on the LatticeNucleon-Roper Transition Form Factors on the Lattice

Transverse Charge Densities of the Nucleon and N -> Roper Transverse Charge Densities of the Nucleon and N -> Roper

(in collaboration with Marc Vanderhaeghen)(in collaboration with Marc Vanderhaeghen)

Updated Form Factors for higher ResonancesUpdated Form Factors for higher ResonancesUpdated Form Factors for higher ResonancesUpdated Form Factors for higher Resonances

comparison with:

• Maid2003 (EPJ A17, 2003, 357)

• Maid2007 (EPJ A34, 2007, 69) • very recent (2008) with K. Park + data included in our database

comparison with:

• Maid2003 (EPJ A17, 2003, 357)

• Maid2007 (EPJ A34, 2007, 69) • very recent (2008) with K. Park + data included in our database

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

no changes for the S11 resonances no changes for the S11 resonances

here the new + data make some considerable differencehere the new + data make some considerable difference

Comparison with the naive non-relativistic quark modelComparison with the naive non-relativistic quark model

• the GM form factor of the (1232) can be extracted directly from the inelastic cross section with high accuracy

• all other electric, magnetic and charge form factors can only beextracted from partial wave analysis

• mostly due to JLab data on p(e,e´0)p we could extract reliable ffs of

P33(1232) GM GE GC

P11(1440) GM ----- GC

D13(1520) GM GE GC

S11(1535)----- GE GC

F15(1680) GM GE GC

Summary and ConclusionsSummary and Conclusions

• recent JLab data on p(e,e´+)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 dLT/das 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 limitedour analysis is based on 890 data points from 1971-1988and most of our neutron ffs are not very conclusive

new data are needed on d(e,e´-p)n

Form Factors in the Electroproduction ProcessForm Factors in the Electroproduction Process

Form Factors in MAID2007Form Factors in MAID2007