arXiv subjects

S. Shinmura

Publications and source records attributed to S. Shinmura.

4 recordsLinked to original sources

arXiv2005

Full-coupled channel approach to S=-2 s-shell hypernuclear systems

We describe full-coupled-channel ab initio calculations among the octet baryons for S=-2 s-shell hypernuclei,_{LambdaLambda}^4H,_{LambdaLambda}^5H and_{LambdaLambda}^6He. The wave function includes Lambda Lambda, Lambda Sigma, N Xi, and Sigma Sigma channels. Minnesota NN, D2^\prime YN and Nijmegen model D simulated YY interactions are used. This is the first attempt to explore the few-body problem of the full-coupled channel scheme for A=4-6, S=-2 multistrangeness hypernuclear systems. Bound state solutions of the Lambda Lambda hypernuclei,_{LambdaLambda}^4H,_{LambdaLambda}^5H and _{LambdaLambda}^6He, are obtained.

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arXiv2004

Full-Coupled Channel Approach to Doubly Strange $s$-Shell Hypernuclei

We describe {\it ab initio} calculations of doubly strange, $S=-2$, $s$-shell hypernuclei ($^4_{ΛΛ}$H, $^5_{ΛΛ}$H, $^5_{ΛΛ}$He and $^6_{ΛΛ}$He) as a first attempt to explore the few-body problem of the {\it full}-coupled channel scheme for these systems. The wave function includes $ΛΛ$, $ΛΣ$, $NΞ$ and $ΣΣ$ channels. Minnesota $NN$, D2$^\prime$ $YN$, and simulated $YY$ potentials based on the Nijmegen hard-core model, are used. Bound state solutions of these systems are obtained. We find that a set of phenomenological $B_8B_8$ interactions among the octet baryons in $S=0, -1$ and -2 sectors, which is consistent with all of the available experimental binding energies of $S=0, -1$ and -2 $s$-shell (hyper-)nuclei, can predict a particle stable bound state of $^4_{ΛΛ}$H. For $^5_{ΛΛ}$H and $^5_{ΛΛ}$He, $ΛN-ΣN$ and $ΞN-ΛΣ$ potentials enhance the net $ΛΛ-NΞ$ coupling, and a large $Ξ$ probability is obtained even for a weaker $ΛΛ-NΞ$ potential.

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arXiv2002

Lambda Lambda-XiN 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 $^6_{ΛΛ}$He has been found to be 0.43 MeV for the coupling strength of the NSC97e potential. This indicates that the free-space $ΛΛ$ interaction is stronger by about $5^{\circ}$ phase shift than that deduced from the empirical data of $^6_{ΛΛ}$He without including the Pauli suppression effect. In $^5_{ΛΛ}$He and $^5_{ΛΛ}$H, an attractive term arising from $ΛΛ$-$Ξ$N conversion is enhanced by the formation of an alpha particle in intermediate $Ξ$ states. According to this enhancement, we have found that the $ΛΛ$ binding energy ($ΔB_{ΛΛ}$) of $^5_{ΛΛ}$He is about 0.27 MeV larger than that of $^6_{ΛΛ}$He for the NSC97e coupling strength. This finding deviates from a general picture that the heavier is the core nucleus, the larger is $ΔB_{ΛΛ}$.

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arXiv1999

Can We Extract Lambda-Lambda Interaction from Two-Particle Momentum Correlation ?

We analyze the invariant mass spectrum of Lambda-Lambda in $^{12}C(K^-,K^+ Lambda Lambda)$ reaction at P(K^+)=1.65 GeV/c by using a combined framework of IntraNuclear Cascade (INC) model and the correlation function technique. The observed enhancement at low-invariant masses can be well reproduced with attractive Lambda-Lambda interactions with the scattering length either in the range a = -6 \sim -4 fm (no bound state) or a = 7 \sim 12 fm (with bound state). We also discuss Lambda-Lambda correlation functions in central relativistic heavy-ion collisions as a possible way to eliminate this discrete ambiguity.

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