ΛΛ-Ξ N coupling effects in light hypernuclei
The significance of ΛΛ-Ξ N coupling in double-Λ hypernuclei has been studied. The Pauli suppression effect due to this coupling in 6ΛΛ He has been found to be 0.43MeV for the coupling strength of the NSC97e potential. This indicates that the free-space ΛΛ interaction is stronger by an about 5° phase shift than that deduced from the empirical data of 6ΛΛ He without including the Pauli suppression effect. In 5ΛΛ He and 5ΛΛ H, an attractive term arising from the ΛΛ-Ξ N conversion is enhanced by the formation of an alpha-particle in the intermediate Ξ states. According to this enhancement, we have found that the ΛΛ binding energy ( ΔBΛΛ) of 5ΛΛ He is about 0.27MeV larger than that of 6ΛΛ He for the NSC97e coupling strength. This finding deviates from the general picture that the heavier is the core nucleus, the larger is ΔBΛΛ.-1
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