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arXiv 0912.1970nucl-th
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耦合道法计算Lambda-9 Be和Lambda-13 C超核的束缚谱和共振谱

Coupled-channel calculation of bound and resonant spectra of Lambda-9Be and Lambda-13C hypernuclei

L. Canton, K. Amos, S. Karataglidis, J. P. Svenne

摘要:

本文用多道代数散射(MCAS)方法分析了两个超核系统Lambda-9 Be和Lambda-13 C的能谱。在11 MeV激发下,λ-13 C中两个奇宇称激发能级(1/2^-和3/2^-)的分裂主要是由弱的λ核自旋轨道力驱动的,但λ-9 Be和λ-13 C中3/2^+和5/2^+能级的分裂有不同的起源。这些情况下似乎是由耦合到集体2+状态的核心核。使用简单的唯象势作为输入的MCAS方法,观察到的分裂和水平排序在λ-9 Be再现与超子和自旋之间的弱自旋-自旋相互作用的激发目标。由于没有这种自旋-自旋相互作用,Lambda-9 Be的能级顺序与目前观察到的相反。在这两个超核中,我们的计算表明,在λ-核连续体中存在额外的低共振态。

英文摘要:

A Multi-Channel Algebraic Scattering (MCAS) approach has been used to analyze the spectra of two hyper-nuclear systems, Lambda-9Be and Lambda-13C. The splitting of the two odd-parity excited levels (1/2^- and 3/2^-) at 11 MeV excitation in Lambda-13C is driven mainly by the weak Lambda-nucleus spin-orbit force, but the splittings of the 3/2^+ and 5/2^+ levels in both Lambda-9Be and Lambda-13C have a different origin. These cases appear to be dominated by coupling to the collective 2+ states of the core nuclei. Using simple phenomenological potentials as input to the MCAS method, the observed splitting and level ordering in Lambda-9Be is reproduced with the addition of a weak spin-spin interaction acting between the hyperon and the spin of the excited target. With no such spin-spin interaction, the level ordering in Lambda-9Be is inverted with respect to that currently observed. In both hyper-nuclei, our calculations suggest that there are additional low-lying resonant states in the Lambda-nucleus continua.

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