The gluing equations of a cusped hyperbolic
–manifold
are
a system of polynomial equations in the shapes of an ideal triangulation
of
that describe the complete hyperbolic structure of
and
its deformations. Given a Neumann–Zagier datum (comprising the shapes
together with the gluing equations in a particular canonical form) we
define a formal power series with coefficients in the invariant trace field of
that
should (a) agree with the asymptotic expansion of the Kashaev invariant to all
orders, and (b) contain the nonabelian Reidemeister–Ray–Singer torsion of
as its first
subleading “–loop”
term. As a case study, we prove topological invariance of the
–loop part of
the constructed series and extend it into a formal power series of rational functions on the
character
variety of .
We provide a computer implementation of the first three terms of the
series using the standard
SnapPy toolbox and check numerically the
agreement of our torsion with the Reidemeister–Ray–Singer for all
hyperbolic knots with at most 14 crossings. Finally, we explain
how the definition of our series follows from the quantization of
–dimensional
hyperbolic geometry, using principles of topological quantum
field theory. Our results have a straightforward extension to any
–manifold
with torus boundary components (not necessarily hyperbolic)
that admits a regular ideal triangulation with respect to some
representation.