Deformation and weak decay of Lambda hypernuclei

TL;DR

This paper investigates the deformation and decay properties of Lambda hypernuclei using self-consistent mean-field theories, revealing shape changes due to Lambda addition and decay rate variations with mass number.

Contribution

It applies relativistic mean-field and Skyrme Hartree-Fock methods to analyze deformation and decay, highlighting shape alterations and decay rate trends in hypernuclei.

Findings

Lambda addition can drastically change nuclear shape, as in $^{28}$Si.

Decay rates increase with mass number in neutron-rich hypernuclei.

Most hypernuclei have similar deformation to their core nuclei.

Abstract

We use the self-consistent mean-field theory to discuss the ground state and decay properties of $\Lambda$ hypernuclei. We first discuss the deformation of $\Lambda$ hypernuclei using the relativistic mean-field (RMF) approach. We show that, although most of hypernuclei have a similar deformation parameter to the core nucleus, the shape of $^{28}$Si is drastically altered, from oblately deformed to spherical, if a $\Lambda$ particle is added to this nucleus. We then discuss the pionic weak decay of neutron-rich $\Lambda$ hypernuclei using the Skyrme Hartree-Fock + BCS method. We show that, for a given isotope chain, the decay rate increases as a function of mass number, due to the strong neutron-proton interaction.