Observation of ${D}_{s}^{+}\to p\overline{n}$ and confirmation of its large branching fraction

The baryonic decay ${D}_{s}^{+}\to p\overline{n}$ is observed, and the corresponding branching fraction is measured to be $\left(1.21±0.10±0.05\right)×{10}^{-3}$, where the first uncertainty is statistical and second systematic. The data sample used in this analysis was collected with the BESIII detector operating at the BEPCII ${e}^{+}{e}^{-}$ double-ring collider with a center-of-mass energy of 4.178 GeV and an integrated luminosity of $3.19\text{}\text{}{\mathrm{fb}}^{-1}$. The result confirms the previous measurement by the CLEO Collaboration and is of greatly improved precision. This result will improve our understanding of the dynamical enhancement of the $W$-annihilation topology in the charmed meson decays.