Limits on the Rate of Emission of Negative-Energy Tachyons

Since the proton is unstable against the tachyonic decay $p\to p+t^0$, in which the tachyon, $t^0$, has negative energy, we have investigated the limits that can be imposed on such an apparently energy-nonconserving process, as well as on the related process, $p\to p+t+\overline{t}$. Exceedingly long lifetimes for these decays (as well as the corresponding ones involving electrons) were obtained (a) from a careful examination of 5500 bubble-chamber pictures from a special exposure, (b) from reinterpretation of experiments searching for baryon and electron nonconservation, and (c) from data on the heat flow emanating from the earth. The interaction mediating such processes must be much weaker than the gravitational interaction.