We introduce a family of matrix dilogarithms, which are automorphisms of
,
being any odd positive integer, associated to hyperbolic ideal tetrahedra
equipped with an additional decoration. The matrix dilogarithms satisfy
fundamental five-term identities that correspond to decorated versions of the
move on
–dimensional
triangulations. Together with the decoration, they arise from the solution we give of a
symmetrization problem for a specific family of basic matrix dilogarithms, the classical
() one
being the Rogers dilogarithm, which only satisfy one special instance of five-term identity.
We use the matrix dilogarithms to construct invariant state sums for closed oriented
–manifolds
endowed with a flat
principal –bundle
, and a fixed
non empty link
if ,
and for (possibly “marked”) cusped hyperbolic
–manifolds
. When
the state sums
recover known simplicial formulas for the volume and the Chern–Simons invariant. When
, the invariants
for are new;
those for triples
coincide with the quantum hyperbolic invariants defined by the first author,
though our present approach clarifies substantially their nature. We
analyse the structural coincidences versus discrepancies between the cases
and
,
and we formulate “Volume Conjectures”, having geometric
motivations, about the asymptotic behaviour of the invariants when
.
Keywords
dilogarithms, state sum invariants, quantum field theory,
Cheeger–Chern–Simons invariants, scissors congruences,
hyperbolic 3–manifolds.