Cover Story (Issue 2, 2023) | Observations of the Cabibbo-Suppressed decays Λ+c ->n π+π0, n π+π-π+ and theCabibbo-Favored decay Λ+c -> n K-π+π+
Authors: BESIII Collaborations
Abstract：Using electron-positron annihilation datasamples corresponding to an integrated luminosity of 4.5 fb−1, collected by the BESIII detector in the energy region between 4599.53 MeV and 4698.82 MeV, we report the firstobservations of the Cabibbo-suppressed decays Λ+c→nπ+π0, Λ+c→nπ+π−π+,and the Cabibbo-favored decay Λ+c→nK−π+π+ withstatistical significances of 7.9σ, 7.8σ, and >10σ, respectively. The branching fractions of these decays are measured tobe B( Λ+c→nπ+π0) = (0.64±0.09±0.02)%, B( Λ+c→nπ+π−π+) = (0.45±0.07±0.03)%, and B( Λ+c nK−π+π+)= (1.90±0.08±0.09)%, wherethe first uncertainties are statistical and the second are systematic. We findthat the branching fraction of the decay Λ+c→nπ+π0 isabout one order of magnitude higher than that of Λ+c→nπ+.
Key words: Λ+c baryon,branching fraction, BESIII detector
