At time , the accelerated Proton has momentum and, by the relativistic energy-momentum relation, energy
The incident Cosmic microwave background photon adds energy . Since the final state contains only the Delta-plus baryon, conservation of relativistic energy gives its laboratory-frame Lorentz factor
Its rest-frame decay time is a proper time, so time dilation gives the laboratory decay time
In the parent's rest frame, momentum conservation makes the massive daughter and photon momenta equal and opposite, of magnitude . The relativistic two-body decay formulas give
Since and ,
The daughter's Lorentz factor is
If it decays after proper time , time dilation gives , while uniform motion gives . Therefore the event coordinates in the parent frame are
Since ,
Relative to the distant observer, the static clock suffers gravitational time dilation. The orbiting clock suffers the same gravitational effect together with the kinematic time dilation caused by its orbital motion, so it accumulates the least proper time.