(Oscillating) non-exponential decays of unstable states

Understand

We discuss deviations from the exponential decay law which originate when going beyond the Breit-Wigner distribution for an unstable state.

• In particular, we concentrate on an oscillating behavior, reminiscent of the Rabi-oscillations, in the short-time region.
• We propose that these oscillations can explain the GSI experiment, which measured superimposed oscillations on top of the exponential law for hydrogen-like nuclides decaying via electron-capture (the so-called GSI anomaly).
• Moreover, we discuss the possibility, that the deviations from the Breit-Wigner distribution in the case of the GSI anomaly are (predominantly) caused by the interaction of the unstable state with the measurement apparatus.