Proton decay cannot be suppressed kinematically

Using a recently derived decay-law formula for relativistic unstable particles, we examine how the decay of a free proton could be affected by the size and shape of the wave packet. For simplicity, the proton is assumed to be spherically symmetric and spinless. The decay probability is found to be lessened comparing to the theoretically expected one; however, the effect is insignificant under realistic experimental conditions. Hence the proton decay is not likely to be suppressed kinematically, contrary to the prediction of a paper by Fleming.