A New Look at the Neutron and the Lamb Shift
  The rest mass of the neutron is exactly equal to the rest mass of a proton plus that of an electron plus the mass equivalent of the kinetic energy of those two particles after they have electrostatically accelerated from very far apart toward each other to a separation distance of one proton diameter. That fact is either a remarkable coincidence or evidence that the neutron is a combination of a proton and an electron. The calculation of this sheds new light on the nature and significance of the Lamb Shift. 
Roger Ellman (The-Origin Foundation, Inc)