Violation of Siegert's theorem in the electro-excitation of the (1−, T = 0)-level at 7.117 MeV in 16O

Abstract Cross sections are measured for the electro-excitation of the first 1 − -level in 16 O at extremely small momentum transfer. The model-independent interpretation with a Fourier-Bessel expansion of the transition charge density reveals an incompatibility with the life-time measurement at the photon point, i.e. a violation of Siegert's theorem.