Helicity analysis of semileptonic hyperon decays including lepton-mass effects A. Kadeer, J. G. Körner and U. Moosbrugger Eur. Phys. J. C, 59 1 (2009) 27-47 Published online: 26 November 2008 DOI: 10.1140/epjc/s10052-008-0801-5