In this post, I will carry a Calabi-Yau fourfold compactification of M-theory in a topologically smooth way. Since M-theory is the only quantum theory of gravity that provably has a finite renormalization group and is the only complete self-consistent GUT, such 4-D compactifications are essential in order to have a correspondence with 4-D spacetime. Recall I derived, via Clifford algebraic symmetry, the total action:
which is deep since Clifford algebras are a quantization of exterior algebras, and applying to the ‘Einstein-Minkowski’ tangent bundle, we get via Gaussian matrix elimination, an expansion of via Green-functions, yielding M-Theory’s action:
with the kappa symmetry gravitonic term and the supergravitational Hamiltonian term being:
Let be a smooth Calabi-Yau fourfold and start with the bosonic 11-D SuGra sector
Start with the total M-theory action
Beginning with dimensional reduction of 11-D supergravity on , the bosonic part is given by:
with the 11-D Ricci scalar and the 4-form field strength for the 4-form . Let be a metric on the Calabi-Yau 4-fold and pick the following backgrounds:
and
which ensure that the effective theory is a three-dimensional N = 2 supergravity one. Massless modes that arise from fluctuations of the metric are encoded by a Kähler form expanded as
with the basis of harmonic two-forms and are 3-D scalar fields parametrizing the Kähler structure-deformations of .
Now, the massless modes that come from Heisenberg-fluctuations of M-theory’s three-form are
with
and a basis of harmonic (1, 2)-forms, with parametrization
with an integral-harmonic three-forms basis and holomorphic in complex structure.
Thus, we have
with the following holding:
and
Now, substituting the ansatz
and
into:
After a Weyl rescaling, thus bringing the effective action into Einstein-Sasaki frame, the 3-D effective theory is hence given by
The central mathematical entities in this expression, since I am working in M-theory, is the rescaled Kähler moduli
with
and the following identity holding:
and expresses the intersection number of two-forms. Since the kinetic term for complex structure moduli depends on the Sasaki-Kähler metric:
with a basis of harmonic (3, 1)-forms and .
We can derive:
with the definitions:
and I explicitly used
and the couplings:
and
and made a green-functional use of
So we get then the following identities:
and
with complex and Kähler structure independent intersection numbers:
and
by solving
and via change-of-variables, substituting in
one gets a solution to that dimensionally reduces to a Calabi-Yau hypersurface in weighted projective four-dimensional space, which is isomorphic to compactification on