Two-flavor chiral perturbation theory at nonzero isospin: pion condensation at zero temperature Prabal Adhikari, Jens O. Andersen and Patrick Kneschke Eur. Phys. J. C, 79 10 (2019) 874 Published online: 24 October 2019 DOI: 10.1140/epjc/s10052-019-7381-4