Using $(10087 \pm 44)\times10^{6}$ $J/\psi$ events collected with the BESIII detector operating at the BEPCII storage ring in 2009, 2012, 2018, and 2019, we perform a search for the reaction $\bar{\Lambda}n \to \Lambda\Lambda X$, where $X$ denotes any additional final-state particles. Given the highly suppressed phase space for producing extra pions, $X$ consists of either nothing or a photon, corresponding to the processes $\bar{\Lambda}n \to \Lambda\Lambda$ and $\bar{\Lambda}n \to H\gamma \to \Lambda\Lambda\gamma$. The $\bar{\Lambda}$ originates from the decay $J/\psi \to \Lambda\bar{\Lambda}$, while the neutron comes from the material of the beam pipe. A signal is observed for the first time with a statistical significance of $6.4\sigma$. The cross section for the reaction is measured to be $$\sigma(\bar{\Lambda}+{}^{9}\mathrm{Be}\to\Lambda+\Lambda+X)=\left(43.6 \pm 10.5\,(\mathrm{stat}) \pm 11.1\,(\mathrm{syst})\right)\,\mathrm{mb},$$ at a $\bar{\Lambda}$ momentum of approximately $0.818~\mathrm{GeV}/c$, where the first uncertainty is statistical and the second is systematic. No significant $H$-dibaryon signal is observed in the $\Lambda\Lambda$ final state.

Experimental study of the reaction Ξ0⁢𝑛→Λ⁢Λ⁢𝑋 using Ξ0-nucleus scattering

Garzia, I.;Melendi, F. M.;
2026

Abstract

Using $(10087 \pm 44)\times10^{6}$ $J/\psi$ events collected with the BESIII detector operating at the BEPCII storage ring in 2009, 2012, 2018, and 2019, we perform a search for the reaction $\bar{\Lambda}n \to \Lambda\Lambda X$, where $X$ denotes any additional final-state particles. Given the highly suppressed phase space for producing extra pions, $X$ consists of either nothing or a photon, corresponding to the processes $\bar{\Lambda}n \to \Lambda\Lambda$ and $\bar{\Lambda}n \to H\gamma \to \Lambda\Lambda\gamma$. The $\bar{\Lambda}$ originates from the decay $J/\psi \to \Lambda\bar{\Lambda}$, while the neutron comes from the material of the beam pipe. A signal is observed for the first time with a statistical significance of $6.4\sigma$. The cross section for the reaction is measured to be $$\sigma(\bar{\Lambda}+{}^{9}\mathrm{Be}\to\Lambda+\Lambda+X)=\left(43.6 \pm 10.5\,(\mathrm{stat}) \pm 11.1\,(\mathrm{syst})\right)\,\mathrm{mb},$$ at a $\bar{\Lambda}$ momentum of approximately $0.818~\mathrm{GeV}/c$, where the first uncertainty is statistical and the second is systematic. No significant $H$-dibaryon signal is observed in the $\Lambda\Lambda$ final state.
2026
Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ai, X. C.; Aliberti, R.; Amoroso, A.; An, Q.; Bai, Y.; Bakina, O.; Ban, Y.; Bao, H. -R.; Batozskaya, V.; Be...espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11392/2634971
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