This equation reads, the angular momentum of the neutron is equal to the angular momentum of the proton plus the angular momentum of the electron times the electron g-factor times half spin.  The electron g-factor is multiplied by half spin because all the subatomic particle angular momentum has inherent half spin.

The gyromagnetic ratio of the electron  is given by NIST as:

where µ_e is the magnetic moment of the electron, and h is Planck's constant.  In the Quantum Physics Model the magnetic moment is transposed to units of distributed charge:

So the gyromagnetic ratio of the electron in the Quantum Physics Model is:

egmr is the electron gyromagnetic ratio in the Quantum Physics Model.  Applying quantum dimensions to egmr:

This reads as: the gyromagnetic ratio of the electron is equal to the elementary charge of the electron divided by the mass of the electron times the half spin of the electron g-factor.

Where does this energy or mass come from?  It likely comes from the kinetic energy of the electron when it slams into the proton.  The kinetic energy is probably a threshold energy, so that an electron excited to about 1.253 x 10^-13 joules can be captured by a proton. 

The half spin g-factor of the electron enables this excess energy to remain contained in the proton until the resulting neutron is no longer attached to a proton, or until the neutron has a weak binding in the nucleus due to the half spin structure of spacetime.  

To see where the weak interaction (weak nuclear force) would come into the equation, the electron gyromagnetic ratio can be also written in terms of the strong charge and weak interaction:

where 8πx are the weak interactions of each of the particles.  With a little investigation it should be possible to determine which weak interaction is responsible for the neutron decay, but I would guess it is the electron weak interaction.

The gyromagnetic ratio of the proton and neutron are derived similar that of the electron, except that it is seen the gyromagnetic ratio is due to the larger particle's relationship to the electron.  In other words, the electron is the key destabilizing mechanism of the atom.