Özet
We report the first direct measurement of decays of theΛþcbaryon involving the neutron. The analysis isperformed using567pb−1ofeþe−collision data collected atffiffiffisp¼4.599GeV with the BESIII detector atthe BEPCII collider. We observe the decayΛþc→nK0Sπþand measure the absolute branching fraction to beBðΛþc→nK0SπþÞ¼½1.82 0.23ðstatÞ 0.11ðsystÞ %. A comparison toB½Λþc→pð ̄KπÞ0 provides animportant test of isospin symmetry and final state interactions