Effects of $\Lambda \Lambda -\Xi N$ mixing in the decay of $S=-2$ hypernuclei

Abstract

We study the non-mesonic weak decay of the doubly-strange hypernucleus ${}_6^{\Lambda \Lambda }$He within a model which considers the exchange of pseudoscalar and vector mesons. Special attention is paid into quantifying the strong interaction effects, focussing on the interaction among the two Λ hyperons which induces novel weak transitions, whereby ΛΛ, ΞN and ΣΣ states decay into a hyperon-nucleon pair. The initial strangeness -2 wave function is obtained from the solution of a G-matrix equation with the input of realistic strong baryon-baryon potentials, while the final hyperon-nucleon wave functions are derived analogously from a microscopic T-matrix calculation. The new ΛΛ $\to$ Y N decay rate studied in this work, ${\Gamma }_{\Lambda n}+{\Gamma }_{{\Sigma }^{0}n}+{\Gamma }_{{\Sigma }^{-}p}$ , represents 3-4% of the total one-baryon induced non-mesonic decay and is remarkably affected by strong interaction effects. In particular, the relative importance of the partial decay rates, encoded in the ratio ${\Gamma }_{\Lambda n}/({\Gamma }_{{\Sigma }^{0}n}+{\Gamma }_{{\Sigma }^{-}p})$, gets inverted when the mixing to ΞN states is incorporated in the initial correlated ΛΛ wave function. This sensitivity can be used experimentally to learn about the strong interaction in the strangeness -2 sector.

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Cited by in corpus (1)

• Hypernuclear constraints on the existence and lifetime of a deeply bound $H$ dibaryon