Isospin odd πK scattering length

We make use of the chiral two-loop representation of the πK scattering amplitude [J. Bijnens, P. Dhonte, P. Talavera, JHEP 0405 (2004) 036] to investigate the isospin odd scattering length at next-to-next-to-leading order in the SU(3) expansion. This scattering length is protected against contributions of ms in the chiral expansion, in the sense that the corrections to the current algebra result are of order Mπ2. In view of the planned lifetime measurement on πK atoms at CERN it is important to understand the size of these corrections.