On the ${\Sigma }^1$ and ${\Sigma }^2$-invariants of Artin groups

Abstract

We prove the ${\Sigma }^1$-conjecture for two families of Artin groups: Artin groups such that there exists a prime number $p$ dividing $\frac{l(e)}{2}$ for every edge $e$ with even label $>2$ and balanced Artin groups. The family of balanced Artin groups extends two previously studied families: the one considered by Kochloukova in arXiv:2009.14269, and the family of coherent Artin groups. We state a conjecture on the ${\Sigma }^2$-invariant for Artin groups satisfying the $K(\pi ,1)$-conjecture. The conjecture is proven to be true for two significant families: $2$-dimensional and coherent Artin groups. In the $2$-dimensional case we are able to compute ${\Sigma }^n$ for all $n\ge 2$ and to derive finiteness properties of the derived subgroup.

19 pages. Fixes a mistake in the proof of Theorem 1.2, by refining the definition of balanced Artin groups