$$p\bar{\varLambda }$$ final-state interaction in the reactions $$e^+e^- \rightarrow K^- p \bar{\varLambda }$$ and $$J/\psi \rightarrow K^- p \bar{\varLambda }$$

Abstract

AbstractNear-threshold $$p\bar{\Lambda }$$ p Λ ¯ mass spectra for the reactions $$e^+e^- \rightarrow K^- p\bar{\Lambda }$$ e + e - → K - p Λ ¯ and $$J/\psi \rightarrow K^- p\bar{\Lambda }$$ J / ψ → K - p Λ ¯ are investigated with an emphasis on the role played by the interaction in the $$p\bar{\Lambda }$$ p Λ ¯ system. As guideline for the $$p\bar{\Lambda }$$ p Λ ¯ interaction a variety of $$\Lambda \bar{\Lambda }$$ Λ Λ ¯ potential models is considered that have been established in the analysis of data on $$p{\bar{p}}\rightarrow \Lambda \bar{\Lambda }$$ p p ¯ → Λ Λ ¯ in the past. Arguments why the properties of the $$p\bar{\Lambda }$$ p Λ ¯ and $$\Lambda \bar{\Lambda }$$ Λ Λ ¯ interactions can be expected to be very similar are provided. It is shown that the near-threshold enhancement in the invariant mass observed for the $$e^+e^-$$ e + e - reaction can be reproduced quantitatively by the assumed $$p\bar{\Lambda }$$ p Λ ¯ final-state interaction in the partial wave suggested by an amplitude analysis of the experiment. The effect of the $$p\bar{\Lambda }$$ p Λ ¯ final-state interaction in other decays is explored, including the recently measured reactions $$B^- \rightarrow J/\psi \, {\bar{p}} \Lambda $$ B - → J / ψ p ¯ Λ and $$B^+ \rightarrow J/\psi \, p \bar{\Lambda }$$ B + → J / ψ p Λ ¯ . It is found that the final-state interaction improves the description of the measured invariant mass near threshold in most cases.