A new angle on an old problem: helicity approach to neutron beta decay in the Standard Model Stefan Groote, Jürgen G. Körner and Blaženka Melić Eur. Phys. J. C, 79 11 (2019) 948 Published online: 20 November 2019 DOI: 10.1140/epjc/s10052-019-7453-5