Observation of $\Lambda^+_{c}\to nK^0_S\pi^+$
  We report the first direct measurement of decays of the $\Lambda^+_c$ baryon involving the neutron. The analysis is performed using 567 pb$^{-1}$ of $e^+e^-$ collision data collected at $\sqrt{s}=4.599$ GeV with the BESIII detector at the BEPCII collider. We observe the decay $\Lambda^+_{c}\rightarrow n K^0_S\pi^+$ and measure the absolute branching fraction to be $\mathcal{B}({\Lambda^+_{c}\rightarrow n K^0_S\pi^+})=(1.82\pm0.23({\rm stat})\pm0.11({\rm syst}))\%$. A comparison to $\mathcal{B}({\Lambda^+_{c}\rightarrow p(\bar{K}\pi)^0})$ provides an important test of isospin symmetry and final state interactions. 
M. Ablikim, M. N. Achasov, S. Ahmed, X. C. Ai, O. Albayrak, M.   Albrecht, D. J. Ambrose, A. Amoroso, F. F. An, Q. An, J. Z....
hep-ex