# Irrationality and monodromy for cubic threefolds

## TL;DR

This paper explores the monodromy of smooth cubic threefolds, revealing its non-factorization through the genus five mapping class group, and connects this to the irrationality of these threefolds from a geometric group theory perspective.

## Contribution

It demonstrates that the cohomological monodromy for cubic threefolds does not factor through the genus five mapping class group, offering a new geometric group theory insight into their irrationality.

## Key findings

- Monodromy does not factor through the genus five mapping class group.
- Provides a geometric group theory perspective on irrationality.
- Connects monodromy properties to irrationality of cubic threefolds.

## Abstract

We show the cohomological monodromy for the universal family of smooth cubic threefolds does not factor through the genus five mapping class group. This gives a geometric group theory perspective on the well-known irrationality of cubic threefolds.