arXiv 1503.061252015-03-20nucl-th

双λ超核非介子弱衰变的微观研究

The Non-Mesonic Weak Decay of Double-Lambda Hypernuclei: A Microscopic Approach

E. Bauer, G. Garbarino, C. A. Rodriguez Peña

备注：: 17 pages, 2 figures

摘要：

本文用微观图解方法研究了双$Λ$超核的非介子弱衰变。除了核子诱导机制，$ΛN\to nN$，广泛研究在单- $Λ$超核，额外的超子诱导机制，$ΛΛ\to Λn$，$ΛΛ\to Σ^0 n$和$ΛΛ\to Σ^-p$，在双- $Λ$超核，并在这里进行了研究。在以前的工作单- $Λ$超核，我们采用核物质形式主义扩展到有限核通过局域密度近似和一个介子交换弱跃迁势（包括基态赝标和矢量八重态介子）补充相关和不相关的两个-π-交换贡献。计算了实验上可接近的轻超核$^{10}_{ΛΛ}$ Be和$^{13}_{ΛΛ}$ B的弱衰变率。我们的预测与以前的一些评价进行了比较。$ΛΛ\to Λn$衰变的速率主要由$K$ -、$K^*$ -和$η$ -交换决定，结果约为游离$Λ$衰变速率$Γ_Λ^{\rm free}$的2.5%，而$ΛΛ\to Σ^0 n$和$ΛΛ\to Σ^- p$衰变的总速率主要由$π$ -交换决定，约为$Γ_Λ^{\rm free}$的0.25%。这些衰变的实验测量对于系统研究奇异超核$-2$的非介子衰变是必不可少的。这一研究领域也可以揭示$H$ --双重子的可能存在和性质。

英文摘要：

The non--mesonic weak decay of double--$Λ$ hypernuclei is studied within a microscopic diagrammatic approach. Besides the nucleon--induced mechanism, $ΛN\to nN$, widely studied in single--$Λ$ hypernuclei, additional hyperon--induced mechanisms, $ΛΛ\to Λn$, $ΛΛ\to Σ^0 n$ and $ΛΛ\to Σ^-p$, are accessible in double--$Λ$ hypernuclei and are investigated here. As in previous works on single--$Λ$ hypernuclei, we adopt a nuclear matter formalism extended to finite nuclei via the local density approximation and a one--meson exchange weak transition potential (including the ground state pseudoscalar and vector octets mesons) supplemented by correlated and uncorrelated two--pion--exchange contributions. The weak decay rates are evaluated for hypernuclei in the region of the experimentally accessible light hypernuclei $^{10}_{ΛΛ}$Be and $^{13}_{ΛΛ}$B. Our predictions are compared with a few previous evaluations. The rate for the $ΛΛ\to Λn$ decay is dominated by $K$--, $K^*$-- and $η$--exchange and turns out to be about 2.5\% of the free $Λ$ decay rate, $Γ_Λ^{\rm free}$, while the total rate for the $ΛΛ\to Σ^0 n$ and $ΛΛ\to Σ^- p$ decays, dominated by $π$--exchange, amounts to about 0.25\% of $Γ_Λ^{\rm free}$. The experimental measurement of these decays would be essential for the beginning of a systematic study of the non--mesonic decay of strangeness $-2$ hypernuclei. This field of research could also shed light on the possible existence and nature of the $H$--dibaryon.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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