On the asymptotics of the meromorphic 3D-index

Fuente: arXiv
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Main Authors: Hodgson, Craig D., Kricker, Andrew J., Siejakowski, Rafał M.
Format: Preprint
Published: 2021
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_version_ 1866913688550637568
author Hodgson, Craig D.
Kricker, Andrew J.
Siejakowski, Rafał M.
author_facet Hodgson, Craig D.
Kricker, Andrew J.
Siejakowski, Rafał M.
contents In their recent work, Garoufalidis and Kashaev extended the 3D-index of an ideally triangulated 3-manifold with toroidal boundary to a well-defined topological invariant which takes the form of a meromorphic function of 2 complex variables per boundary component and which depends in addition on a quantisation parameter q. In this paper, we study asymptotics of this invariant as q approaches 1 and develop a conjectural asymptotic approximation in the form of a sum of contributions associated to conjugacy classes of certain boundary parabolic PSL(2,C) representations of the fundamental group. Furthermore, we study the coefficients appearing in these contributions, which include the hyperbolic volume, the '1-loop invariant' of Dimofte and Garoufalidis, as well as a new topological invariant of 3-manifolds with torus boundary, which we call the 'beta invariant'. The technical heart of our analysis is the expression of the state-integral of the Garoufalidis--Kashaev invariant as an integral over one connected component of the space of circle-valued angle structures introduced by Luo. Our stationary phase analysis of the asymptotics of this integral reveals many connections to the theory of angle structures and volume optimization. This investigation was motivated by extensive numerical experiments. In addition, we prove a variety of theorems about the quantities appearing in the analysis which support the overall conjectural picture.
format Preprint
id arxiv_https___arxiv_org_abs_2109_05355
institution arXiv
publishDate 2021
record_format arxiv
spellingShingle On the asymptotics of the meromorphic 3D-index
Hodgson, Craig D.
Kricker, Andrew J.
Siejakowski, Rafał M.
Geometric Topology
57M27, 57R56, 30E15
In their recent work, Garoufalidis and Kashaev extended the 3D-index of an ideally triangulated 3-manifold with toroidal boundary to a well-defined topological invariant which takes the form of a meromorphic function of 2 complex variables per boundary component and which depends in addition on a quantisation parameter q. In this paper, we study asymptotics of this invariant as q approaches 1 and develop a conjectural asymptotic approximation in the form of a sum of contributions associated to conjugacy classes of certain boundary parabolic PSL(2,C) representations of the fundamental group. Furthermore, we study the coefficients appearing in these contributions, which include the hyperbolic volume, the '1-loop invariant' of Dimofte and Garoufalidis, as well as a new topological invariant of 3-manifolds with torus boundary, which we call the 'beta invariant'. The technical heart of our analysis is the expression of the state-integral of the Garoufalidis--Kashaev invariant as an integral over one connected component of the space of circle-valued angle structures introduced by Luo. Our stationary phase analysis of the asymptotics of this integral reveals many connections to the theory of angle structures and volume optimization. This investigation was motivated by extensive numerical experiments. In addition, we prove a variety of theorems about the quantities appearing in the analysis which support the overall conjectural picture.
title On the asymptotics of the meromorphic 3D-index
topic Geometric Topology
57M27, 57R56, 30E15
url https://arxiv.org/abs/2109.05355