The pi(+)-emission puzzle in He-4(Lambda) decay

We re-examine the puzzling pi(+) emission from the weak decay of He-4(Lambda) and purpose an explanation in terms of a three-body decay similar to of the virtual Sigma(+). Such a resolution of the pi(+) decay puzzle is consistent with the calculated Sigma(+) probability in light Lambda hypernuclei as well as the experimentally observed pi(+) energy spectrum and s-wave angular distribution. (C) 1998 Elsevier Science B.V.