English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

The non--mesonic weak decay of double--$\Lambda$ hypernuclei is studiedwithin a microscopic diagrammatic approach. Besides the nucleon--inducedmechanism, $\Lambda N\to nN$, widely studied in single--$\Lambda$ hypernuclei,additional hyperon--induced mechanisms, $\Lambda \Lambda\to \Lambda n$,$\Lambda \Lambda\to \Sigma^0 n$ and $\Lambda \Lambda\to \Sigma^-p$, areaccessible in double--$\Lambda$ hypernuclei and are investigated here. As inprevious works on single--$\Lambda$ hypernuclei, we adopt a nuclear matterformalism extended to finite nuclei via the local density approximation and aone--meson exchange weak transition potential (including the ground statepseudoscalar and vector octets mesons) supplemented by correlated anduncorrelated two--pion--exchange contributions. The weak decay rates areevaluated for hypernuclei in the region of the experimentally accessible lighthypernuclei $^{10}_{\Lambda\Lambda}$Be and $^{13}_{\Lambda\Lambda}$B. Ourpredictions are compared with a few previous evaluations. The rate for the$\Lambda \Lambda\to \Lambda n$ decay is dominated by $K$--, $K^*$-- and$\eta$--exchange and turns out to be about 2.5\% of the free $\Lambda$ decayrate, $\Gamma_{\Lambda}^{\rm free}$, while the total rate for the $\Lambda\Lambda\to \Sigma^0 n$ and $\Lambda \Lambda\to \Sigma^- p$ decays, dominated by$\pi$--exchange, amounts to about 0.25\% of $\Gamma_{\Lambda}^{\rm free}$. Theexperimental measurement of these decays would be essential for the beginningof a systematic study of the non--mesonic decay of strangeness $-2$hypernuclei. This field of research could also shed light on the possibleexistence and nature of the $H$--dibaryon.

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