Electromagnetic Form-Factors of n* Resonances and their Determination from Pion Electroproduction
Feb, 197529 pages
Published in:
- Nucl.Phys.B 93 (1975) 109-137
- Published: 1975
Report number:
- DESY-75-04
Citations per year
Abstract: (Elsevier)
We show how N ∗ electromagnetic form factors can be parameterised in a simple way to take account of their known behaviour at threshold. Using such form factors and Breit-Wigners to represent the final-state interaction we calculate the imaginary parts of the invariant amplitudes for the process eN → eN π , the real parts are calculated from fixed t dispersion relations. The complete amplitudes are then fit to the coincidence data in the resonance region (0 < | λ 2 | < 1.0 GeV 2 ; w < 2 GeV) in order to determine the form factor parameters. Results are presented for the λ 2 dependence of the resonant multipoles and in particular we find stable results for the P 11 (1434), S 11 (1505), D 13 (1520), F 15 (1688) and F 37 (1940). A critical discussion is given of the effect of theoretical uncertainties on the results. We use our results to calculate the helicity asymmetry A on the resonant peaks seen in eN scattering and find that on the 2nd and 3rd peaks A changes sign in the vicinity of λ 2 = −1 GeV 2 .- NUCLEON RESONANCE: FORM FACTOR
- FORM FACTOR: NUCLEON RESONANCE
- PI: ELECTROPRODUCTION
- ELECTROPRODUCTION: PI
- FINAL-STATE INTERACTION
- ELECTRON NUCLEON: INTERACTION
- INTERACTION: ELECTRON NUCLEON
- NUCLEON: FINAL STATE
- FINAL STATE: NUCLEON
- PI: FINAL STATE
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