[π^-K⁺] atom   =>   π⁰ + K⁰

The goal is first to observe [π^-K⁺] and [π⁺K^-] atoms
and then to measure their lifetime.

A measurement of the [πK] atom lifetime will shed new light on relevant S-wave πK scattering lengths. A test of chiral perturbation predictions involving - besides the u and d quark - also the s quark (3-flavour case) is of substantial interest: it provides a way to investigate a potential flavour dependence of the quark condensate responsible for chiral symmetry breaking.
The outcome will be a measurement of the difference |a_1/2−a_3/2|, where a_I means the S-wave πK scattering length with isospin I. In a first step DIRAC expects to measure the atom lifetime with 20% and hence the scattering lengths difference with around 10% precision.
The [πK] atom lifetime is predicted to be (3.7±0.4) fs.