"Forbidden" Asymmetries and Choices of Geometry in Proton-Proton Bremsstrahlung

It is shown that the "forbidden" asymmetries in $p-p$ bremsstrahlung, suggested by Moravcsik as a source of off-shell information, contain also large on-shell effects, which are suppressed by just one power of the photon momentum $k$, relative to such effects in other observables. Two separate criteria—large off-shell parameter $\Delta m^2$ and large soft-photon parameter $\frac{k}{E_0}$—are emphasized as necessary for a geometry which enhances off-shell effects.