The aim of the article is an extension of the Monodromy Conjecture of Denef and
Loeser in dimension two, incorporating zeta functions with differential forms and
targeting all monodromy eigenvalues, and also considering singular ambient spaces.
That is, we treat in a conceptual unity the poles of the (generalized) topological zeta
function and the monodromy eigenvalues associated with an analytic germ
defined on a normal
surface singularity .
The article targets the “right” extension in the case when the link of
is a homology
sphere. As a first step, we prove a splice decomposition formula for the topological zeta function
for any
and analytic
differential form ,
which will play the key technical localization tool in the later definitions and
proofs.
Then, we define a set of “allowed” differential forms via a local restriction along each
splice component. For plane curves we show the following three guiding properties: (1) if
is any pole
of with
allowed, then
is a monodromy
eigenvalue of ,
(2) the “standard” form is allowed, (3) every monodromy eigenvalue of
is obtained as in (1)
for some allowed
and some .
For general
we prove (1) unconditionally, and (2)–(3) under an additional (necessary)
assumption, which generalizes the semigroup condition of Neumann–Wahl. Several
examples illustrate the definitions and support the basic assumptions.