Recent years have seen dramatic progress in the determination of multi-hadron observables using lattice QCD (LQCD) Examples include the determination of scattering amplitudes involving multiple two-particle channels (e.g. the scalar-isocalar sector involving two pion and kaon-antikaon channels), and the first study of a nuclear fusion reaction. So far, these calculations use unphysically heavy quarks, but there is steady progress towards the use of quarks with physical masses. However, as quark masses drop, there is an increasing need to develop methods to deal with states containing three or more particles. Here the theoretical methods are only partially developed and lag behind the ability of numerical simulations to extract the energies of such states.

The aim of this workshop is to clarify the landscape of methods for extracting multi-hadron observables from LQCD, and to bridge the gap between LQCD approaches and other techniques---effective field theories, dispersive and amplitude analysis, Dyson-Schwinger equations and other few-body methods.

Specific goals of the workshop are:

1. Based on the present numerical status, set timelines for the calculation of certain multi-hadron observables using LQCD.

2. Better organize the landscape of formal methods dedicated to extracting multi-hadron observables from LQCD.

3. Elucidate the role of multi-hadron LQCD in the context of other methods. By bringing together experts in multi-hadron alternatives to LQCD we will have a unique opportunity to more clearly establish which observables are best suited to which methods.

4. Discuss prospects for using other methods to compliment, supplement or extend the reach of LQCD.

In light of these aims, the workshop will feature a mix of talks summarizing the status of different methods. In addition, we will organize focused discussion sessions to pin down outstanding issues and to identify overlap between different approaches.

There will be a $40 registration fee to attend the workshop. The registration fee includes participation in the workshop, lectures, and coffee breaks.