# Meson-meson scattering lengths at maximum isospin from lattice QCD

## TL;DR

This paper reports lattice QCD calculations of meson-meson scattering lengths at maximum isospin, using chiral perturbation theory for extrapolation, and finds leading order theory closely matches the data across various meson masses.

## Contribution

It provides new lattice QCD determinations of scattering lengths at maximum isospin and demonstrates the effectiveness of leading order chiral perturbation theory in describing these results.

## Key findings

- Leading order chiral perturbation theory closely matches lattice data.
- Scattering lengths were computed at multiple lattice spacings and pion masses.
- Results support the validity of chiral perturbation theory at these energy scales.

## Abstract

We summarize our lattice QCD determinations of the pion-pion, pion-kaon and kaon-kaon s-wave scattering lengths at maximal isospin with a particular focus on the extrapolation to the physical point and the usage of next-to-leading order chiral perturbation theory to do so. We employ data at three values of the lattice spacing and pion masses ranging from around 230 MeV to around 450 MeV, applying Luescher's finite volume method to compute the scattering lengths. We find that leading order chiral perturbation theory is surprisingly close to our data even in the kaon-kaon case for our entire range of pion masses.