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arXiv · 1905.06775

The onset of $ΛΛ$ hypernuclear binding

L. Contessi·M. Schäfer·N. Barnea·A. Gal·J. Mareš
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Abstract

Binding energies of light, $A\leq 6$, $ΛΛ$ hypernuclei are calculated using the stochastic variational method in a pionless effective field theory (EFT) approach at leading order with the purpose of assessing critically the onset of binding in the strangeness S=-2 hadronic sector. The EFT input in this sector consists of (i) a $ΛΛ$ contact term constrained by the $ΛΛ$ scattering length $a_{ΛΛ}$, using a range of values compatible with $ΛΛ$ correlations observed in relativistic heavy ion collisions, and (ii) a $ΛΛN$ contact term constrained by the only available $A\leq 6$ $ΛΛ$ hypernucler binding energy datum of $^{6}_{ΛΛ}$He. The recently debated neutral three-body and four-body systems $^{3}_{ΛΛ}$n and $^{4}_{ΛΛ}$n are found unbound by a wide margin. A relatively large value of $|a_{ΛΛ}| \gtrsim 1.5$ fm is needed to bind $^{4}_{ΛΛ}$H, thereby questioning its particle stability. In contrast, the particle stability of the $A=5$ $ΛΛ$ hypernuclear isodoublet $^{5}_{ΛΛ} $H--$^{5}_{ΛΛ}$He is robust, with $Λ$ separation energy of order 1 MeV.

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L. Contessi, M. Schäfer, N. Barnea, A. Gal, J. Mareš. 2019-08-22. The onset of $ΛΛ$ hypernuclear binding. https://doi.org/10.1016/j.physletb.2019.134893

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