Roots of Alexander polynomials of random positive 3-braids

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Hauptverfasser: Dunfield, Nathan M., Tiozzo, Giulio
Format: Preprint
Veröffentlicht: 2024
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author Dunfield, Nathan M.
Tiozzo, Giulio
author_facet Dunfield, Nathan M.
Tiozzo, Giulio
contents Motivated by an observation of Dehornoy, we study the roots of Alexander polynomials of knots and links that are closures of positive 3-strand braids. We give experimental data on random such braids and find that the roots exhibit marked patterns, which we refine into precise conjectures. We then prove several results along those lines, for example that generically at least 69% of the roots are on the unit circle, which appears to be sharp. We also show there is a large root-free region near the origin. We further study the equidistribution properties of such roots by introducing a Lyapunov exponent of the Burau representation of random positive braids, and a corresponding bifurcation measure. In the spirit of Deroin and Dujardin, we conjecture that the bifurcation measure gives the limiting measure for such roots, and prove this on a region with positive limiting mass. We use tools including work of Gambaudo and Ghys on the signature function of links, for which we prove a central limit theorem.
format Preprint
id arxiv_https___arxiv_org_abs_2402_06771
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Roots of Alexander polynomials of random positive 3-braids
Dunfield, Nathan M.
Tiozzo, Giulio
Geometric Topology
Dynamical Systems
57K14, 37H15 (Primary) 60G50 (Secondary)
Motivated by an observation of Dehornoy, we study the roots of Alexander polynomials of knots and links that are closures of positive 3-strand braids. We give experimental data on random such braids and find that the roots exhibit marked patterns, which we refine into precise conjectures. We then prove several results along those lines, for example that generically at least 69% of the roots are on the unit circle, which appears to be sharp. We also show there is a large root-free region near the origin. We further study the equidistribution properties of such roots by introducing a Lyapunov exponent of the Burau representation of random positive braids, and a corresponding bifurcation measure. In the spirit of Deroin and Dujardin, we conjecture that the bifurcation measure gives the limiting measure for such roots, and prove this on a region with positive limiting mass. We use tools including work of Gambaudo and Ghys on the signature function of links, for which we prove a central limit theorem.
title Roots of Alexander polynomials of random positive 3-braids
topic Geometric Topology
Dynamical Systems
57K14, 37H15 (Primary) 60G50 (Secondary)
url https://arxiv.org/abs/2402.06771