# Unweighted Donaldson-Thomas theory of the banana 3-fold with section classes

## TL;DR

This paper advances the understanding of Donaldson-Thomas theory for banana threefolds, focusing on rank 4 lattice calculations, relating to Pandharipande-Thomas theory, and introducing new Gopakumar-Vafa invariants.

## Contribution

It extends previous work by computing Donaldson-Thomas invariants for a larger lattice and connects these results to Pandharipande-Thomas theory and Gopakumar-Vafa invariants.

## Key findings

- Calculated Donaldson-Thomas invariants for rank 4 lattice.
- Connected Donaldson-Thomas theory to Pandharipande-Thomas theory.
- Presented new Gopakumar-Vafa invariants for banana threefolds.

## Abstract

We further the study of the Donaldson-Thomas theory of the banana threefolds which were recently discovered and studied in [Bryan'19]. These are smooth proper Calabi-Yau threefolds which are fibred by Abelian surfaces such that the singular locus of a singular fibre is a non-normal toric curve known as a "banana configuration". In [Bryan'19] the Donaldson-Thomas partition function for the rank 3 sub-lattice generated by the banana configurations is calculated. In this article we provide calculations with a view towards the rank 4 sub-lattice generated by a section and the banana configurations. We relate the findings to the Pandharipande-Thomas theory for a rational elliptic surface and present new Gopakumar-Vafa invariants for the banana threefold.