# Measurement of the N $\rightarrow \Delta^+$(1232) Transition at High Momentum Transfer by $\pi^0$ Electroproduction

Abstract : We report a new measurement of the exclusive electroproduction reaction gamma* p -> pi0 p to explore the evolution from soft non-perturbative physics to hard processes via the Q2 dependence of the magnetic (M1+), electric (E1+) and scalar (S1+) multipoles in the N to Delta transition. 9000 differential cross section data points cover W from threshold to 1.4 eV/c2, 4pi center-of-mass solid angle, and Q2 from 3 to 6 GeV2/c2, the highest yet achieved. It is found that the magnetic form factor G*M decreases with Q2 more steeply than the proton magnetic form factor, the ratio E1+/M1+ is small and negative, indicating strong helicity non-conservation, and the ratio S1+/M1+ is negative, while its magnitude increases with Q2.
Document type :
Journal articles

http://hal.in2p3.fr/in2p3-00106729
Contributor : Suzanne Robert <>
Submitted on : Monday, October 16, 2006 - 10:46:01 AM
Last modification on : Wednesday, September 16, 2020 - 3:59:58 PM

### Citation

M. Ungaro, P. Stoler, I. Aznauryan, V. D. Burkert, K. Joo, et al.. Measurement of the N $\rightarrow \Delta^+$(1232) Transition at High Momentum Transfer by $\pi^0$ Electroproduction. Physical Review Letters, American Physical Society, 2006, 97, pp.112003. ⟨10.1103/PhysRevLett.97.112003⟩. ⟨in2p3-00106729⟩

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