Geometric volumes needed for calculation of force strengths include:
Force M Vol(M)
gravity S^4 8pi^2/3 - S^4 is 4-dimensional
color CP^2 8pi^2/3 - CP^2 is 4-dimensional
weak S^2 x S^2 2 x 4pi - S^2 is a 2-dim boundary of 3-dim ball
4-dim S^2 x S^2 =
= topological boundary of 6-dim 2-polyball
Shilov Boundary of 6-dim 2-polyball = S^2 + S^2 =
= 2-dim surface frame of 4-dim S^2 x S^
e-mag T^4 4 x 2pi - S^1 is 1-dim boundary of 2-dim disk
4-dim T^4 = S^1 x S^1 x S^1 x S^1 =
= topological boundary of 8-dim 4-polydisk
Shilov Boundary of 8-dim 4-polydisk =
= S^1 + S^1 + S^1 + S^1 =
= 1-dim wire frame of 4-dim T^4
From another point of view, the link manifold to the target vertex is trivial for the abelian neutral U(1) photons of Electromagnetism, so we take QE and DE to be equal to unity.