I have a few doubts on free neutron decay process as mentioned here. The two questions are:
1)Why only a small fraction(~0.001 of the free neutron decays) produces a gamma ray photon?
2)What exactly is the mechanism behind the formation of this photon? The explanation in wikipedia is insufficient as it simply says its due to an "internal bremsstrahlung".
Can someone please explain these two questions.
The vertex interaction of neutron decay is a weak-interaction and it simply doesn't couple to photons (i.e. to gamma rays): there is no way the bare interaction can make a photon at all.
So the events with photons are those where so extra interaction of the decay products occurs and generates a gamma ray. The occurrence of these extra interactions invoke a factor of the fine-structure context $\alpha^2 \approx (1/137)^2$ in the probability of the event, and also alters the phase space available to the decay.
