An analytic analysis of the pion decay constant in three-flavoured chiral perturbation theory B. Ananthanarayan, Johan Bijnens and Shayan Ghosh Eur. Phys. J. C, 77 7 (2017) 497 Published online: 26 July 2017 DOI: 10.1140/epjc/s10052-017-5019-y