Observation of $D^+_s\rightarrow p\bar{n}$ and confirmation of its large branching fraction

Abstract

The baryonic decay $D^+_s\rightarrow p\bar{n}$ is observed, and the corresponding branching fraction is measured to be (1.21±0.10±0.05)×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 3.19fb$^{−1}$. The result confirms the previous measurement by the CLEO Collaboration and is of greatly improved precision, which may deepen our understanding of the dynamical enhancement of the $W$-annihilation topology in the charmed meson decays.