arXiv subjects

Y. Nara

Publications and source records attributed to Y. Nara.

23 records · Page 2Linked to original sources

arXiv1999

Study of relativistic nuclear collisions at AGS energies from p+Be to Au+Au with hadronic cascade model

A hadronic cascade model based on resonances and strings is used to study mass dependence of relativistic nuclear collisions from p+Be to Au+Au at AGS energies ($\sim 10\AGeV$) systematically. Hadron transverse momentum and rapidity distributions obtained with both cascade calculations and Glauber type calculations are compared with experimental data to perform detailed discussion about the importance of rescattering among hadrons. We find good agreement with the experimental data without any change of model parameters with the cascade model. It is found that rescattering is of importance both for the explanation of high transverse momentum tail and for the multiplicity of produced particles.

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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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arXiv1998

Quantum fluctuation effects on hyperfragment formation from Xi^- absorption at rest on 12C

Formation mechanisms of single, twin, and double hypernuclei from Xi^- absorption at rest on 12C are investigated with an refined microscopic transport model, that incorporates the recently developed Quantal Langevin treatment into Antisymmetrized Molecular Dynamics. The quantum fluctuations suppress the formation probability of double hyperfragments to around 10%, which is comparable to the experimental data, and the dynamical formation of twin hyperfragment can be described qualitatively.

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arXiv1997

Branching ratio change in K- absorption at rest and the nature of the Lambda(1405)

We investigate in-medium corrections to the branching ratio in K- absorption at rest and their effect on the (positively and negatively) charged pion spectrum. The in-medium corrections are due to Pauli blocking, which arises if the Lambda(1405) is assumed to be a $\bar{K}$-nucleon bound state and leads to a density and momentum dependent mass shift of the Lambda(1405). Requiring that the optical potential as well as the branching ratio are derived from the same elementary T-matrix, we find that the in-medium corrected, density dependent T-matrix gives a better description of the K- absorption reaction than the free, density-independent one. This result suggests that the dominant component of the Lambda(1405) wave function is the $\bar{K}N$ bound state.

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arXiv1996

K^+ momentum spectrum from (K^-,K^+) reactions in intranuclear cascade model

In a framework of intranuclear cascade (INC) type calculation, we study a momentum spectrum in reactions \KK at a beam momentum of 1.65 GeV/c. INC model calculations are compared with the relativistic impulse approximation (RIA) calculations to perform the detailed study of the reaction mechanism. We find that the INC model can reproduce the experimental data on various targets. Especially, in the low-momentum region, the forward-angle cross sections of the $(K^-,K^+)$ reaction on from light to heavy targets are consistently explained with the two-step strangeness exchange and production processes with various intermediate mesons, and $ϕ$, $a_0$ and $f_0$ productions and their decay into $K^+K^-$. In the two-step processes, inclusion of meson and hyperon resonances is found to be essential.

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