Charge radius the composite particle must be modeled as a sphere of negative rather than positive electric charge for the interpretation of electron scattering experiments. In these cases, the square of the charge radius of the particle is defined to be negative, with the same absolute value with units of length squared equal to the positive squared charge radius that it would have had if it was identical in all other respects but each quark in the particle had the opposite electric charge (with the charge radius itself having a value that is an imaginary number with units of length). It is
Charge radius This asymmetric distribution of charge within the particle gives rise to a small negative squared charge radius for the particle as a whole. But, this is only the simplest of a variety of theoretical models, some of which are more elaborate, that are used to explain this property of a neutron. For deuterons and higher nuclei, it is conventional to distinguish between the scattering charge radius, "r" (obtained from scattering data), and the bound-state charge radius, "R", which includes the Darwin–Foldy term to account for the behaviour of the anomalous magnetic moment in an electromagnetic field and which is appropriate