Observation of $\bar{\hat{I}}›p\to K^{+}\ddot{I}{€}^{+}\ddot{I}{€}^{-}\ddot{I}{€}^0$ and $\bar{\hat{I}}›p\to K^{+}\ddot{I}{€}^{+}\ddot{I}{€}^{-}2\ddot{I}{€}^0$

Abstract

Using $(10087\pm 44)\times 10^6$ $J/\ddot{I}ˆ$ events collected with the BESIII detector at a center-of-mass energy of $\sqrt{s}=3.097$ GeV, the antihyperon-nucleon annihilation processes $\bar{\hat{I}}›p\to K^{+}\ddot{I}{€}^{+}\ddot{I}{€}^{-}+k\ddot{I}{€}^0$ ($k=1,2,3$) are studied at an incident $\bar{\hat{I}}›$ momentum of approximately 1.074 GeV/$c$. The reactions $\bar{\hat{I}}›p\to K^{+}\ddot{I}{€}^{+}\ddot{I}{€}^{-}\ddot{I}{€}^0$ and $\bar{\hat{I}}›p\to K^{+}\ddot{I}{€}^{+}\ddot{I}{€}^{-}2\ddot{I}{€}^0$ are observed for the first time, with corresponding cross sections $\ddot{I}{ƒ}_{\bar{\hat{I}}›p\to K^{+}\ddot{I}{€}^{+}\ddot{I}{€}^{-}\ddot{I}{€}^0}=8.5_{-1.1}^{+1.2}(stat.)\pm 0.4(syst.)$ mb and $\ddot{I}{ƒ}_{\bar{\hat{I}}›p\to K^{+}\ddot{I}{€}^{+}\ddot{I}{€}^{-}2\ddot{I}{€}^0}=7.9_{-1.7}^{+1.9}\pm 0.4$ mb. No significant signal is found for $\bar{\hat{I}}›p\to K^{+}\ddot{I}{€}^{+}\ddot{I}{€}^{-}3\ddot{I}{€}^0$, and an upper limit of 7.2 mb is set at a 90\% confidence level. An evidence for the $K^{\ast }(892{)}^{+}$ resonance is seen in the $K^{+}\ddot{I}{€}^0$ invariant mass spectrum $M_{K^{+}\ddot{I}{€}^0}$ for $k=1$, and the corresponding cross section for $\bar{\hat{I}}›p\to K^{\ast }(892{)}^{+}\ddot{I}{€}^{+}\ddot{I}{€}^{-}$ is measured to be $\ddot{I}{ƒ}_{\bar{\hat{I}}›p\to K^{\ast }(892{)}^{+}\ddot{I}{€}^{+}\ddot{I}{€}^{-}}=12.5_{-3.4}^{+3.8}\pm 1.2$ mb. Owing to the limited statistics, possible interference effects are not considered. These findings offer crucial input to deepen our understanding of the antihyperon-nucleon interactions.