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

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We calculate the ratios E2/M1 and C2/M1 of the multipole amplitudes for electroproduction of the Δ(1232) in the range of photon virtuality 0<-K²<1 GeV² in a chiral chromodielectric model and a linear σ-model. We find that 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 Δ. The A₁/₂ and A₃/₂ amplitudes are reasonably well reproduced in the σ-model; in the chromodielectric model, however, they are a factor of two too small.