About the even minimal stratum of translation surfaces in genus 4

TL;DR

This paper extends the understanding of the monodromy of certain translation surface strata in genus 4, linking them to Artin groups with Dynkin diagram E8, building on previous genus 3 results.

Contribution

It establishes that the stratum ven(6) in genus 4 is an orbifold classifying space for a central extension of the inner automorphism group of the Artin group A_{E_8}.

Findings

Monodromy of ven(6) in genus 4 is highly non-injective.

Stratum ven(6) corresponds to a central extension of Inn(A_{E_8}).

Extends previous genus 3 results to genus 4.

Abstract

In the present note, we complete the correspondence between stratum components of translation surfaces in low genus and finite-type Artin groups with defining Dynkin diagram containing $E_6$. In an earlier work, we showed that in genus $3$ the monodromy of the non-hyperelliptic connected components $\mathcal{H}^{\operatorname{odd}}(4)$ and $\mathcal{H}(3,1)$ are highly non-injective, as the respective kernels contain a non-abelian free group of rank $2$. The result holds since both the stratum components are orbifold classifying spaces for central extensions of the inner automorphism groups of the finite-type Artin groups $A_{E_6}$ and $A_{E_7}$, respectively. The following is a note extending the same result to the stratum $\mathcal{H}^{\operatorname{even}}(6)$ in genus $4$, which is an orbifold classifying space for a central extension of the group $\operatorname{Inn}(A_{E_8})$.