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The role of the pion cloud in electroproduction of the Delta (1232)

Authors: M. Fiolhais, B. Golli and S. Sirca

Ref.: Physics Letters B 373, 229-234 (1996)

Abstract: We calculate the ratios E2/M1 and C2/M1 of the multipole amplitudes for electroproduction of the Delta (1232) in the range of photon virtuality 0<-K2 < 1 GeV 2 in a chiral chromodielectric model and a linear sigma-model. We find the relatively large experimental values can be explained in terms of the pion contribution alone; the contribution arising from d-state quark admixture remains below 10%. We describe the pion cloud as a coherent state and use spin and isospin projection to obtain the physical nucleon and the Delta. The A 1/2 and A 3/2 amplitudes are reasonably well reproduced in the sigma-model; in the chromodielectric model, howeverm they are a factor of two too small.

URL: nautilus.fis.uc.pt