QCD predictions for physical multimeson scattering amplitudes

TL;DR

This paper presents the first lattice QCD calculations of three-particle scattering amplitudes with physical quark masses, providing new insights into meson interactions and validating theoretical models against experimental data.

Contribution

First lattice QCD determination of three-particle scattering amplitudes with physical quark masses for meson systems, including $ ext{π}^+$ and $ ext{K}^+$.

Findings

Good agreement with chiral perturbation theory

First determinations of $ ext{π}^+ ext{K}^+$ and $2 ext{K}^+$ amplitudes at the physical point

Accurate two-meson amplitude results for maximal isospin states

Abstract

We use lattice QCD calculations of the finite-volume spectra of systems of two and three mesons to determine, for the first time, three-particle scattering amplitudes with physical quark masses. Our results are for combinations of $\pi^+$ and $K^+$, at a lattice spacing $a=0.063\;$fm, and in the isospin-symmetric limit. We also obtain accurate results for maximal-isospin two-meson amplitudes, with those for $\pi^+ K^+$ and $2K^+$ being the first determinations at the physical point. Dense lattice spectra are obtained using the stochastic Laplacian-Heaviside method, and the analysis leading to scattering amplitudes is done using the relativistic finite-volume formalism. Results are compared to chiral perturbation theory and to phenomenological fits to experimental data, finding good agreement.