On the Operational Interpretation of Electron Compositeness Bounds

High-energy scattering measurements and precision tests constrain departures from pointlike electron behaviour to operational scales nominally below 10⁻¹⁸ cm. We examine the assumptions connecting such operational bounds to claims about the physical extent of any internally structured electron. The standard inference rests on probe-target factorisation: the assumption that the electromagnetic probe and the target contribute independently to the scattering amplitude, so that all structural information about the target resides in a form factor multiplying a universal probe response. A range of extended-electron models in the published literature — including peer-reviewed nonlinear lepton field theories, renormalisable preon gauge theories, topological compositeness constructions, and recent nonlinear-electrodynamics treatments — proposes internal structure at scales naive readings of scattering bounds would seem to exclude. The Skyrme-model analysis of electron scattering off extended objects provides a concrete worked example in which the inferred form factor depends explicitly on the analysis procedure. We argue that the inference from null scattering results to model-independent claims about physical extent is conditional on assumptions worth scrutinising.