Constraining hypernuclear density functional with $\Lambda$-hypernuclei and compact stars

TL;DR

This paper develops a relativistic density functional theory incorporating hyperons to simultaneously describe hypernuclei and hypernuclear stars, adjusting couplings based on experimental and astronomical data.

Contribution

It introduces a density functional allowing SU(6) symmetry breaking and mixing, providing a unified framework for hypernuclei and compact star modeling with data-driven coupling adjustments.

Findings

Fixed $\sigma$-$\Lambda$ coupling using hypernuclei data.

Derived an upper bound on $\sigma$-$\Sigma$ coupling from neutron star mass constraints.

Ensured the maximum star mass exceeds 2 solar masses.

Abstract

We present a simultaneous calculation of heavy single-$\Lambda$ hypernuclei and compact stars containing hypernuclear core within a relativistic density functional theory based on a Lagrangian which includes the hyperon octet and lightest isoscalar-isovector mesons which couple to baryons with density-dependent couplings. The corresponding density functional allows for SU(6) symmetry breaking and mixing in the isoscalar sector, whereby the departures in the $\sigma$-$\Lambda$ and $\sigma$-$\Sigma$ couplings away from their values implied by the SU(3) symmetric model are used to adjust the theory to the laboratory and astronomical data. We fix $\sigma$-$\Lambda$ coupling using the data on the single-$\Lambda$ hypernuclei and derive an upper bound on the $\sigma$-$\Sigma$ from the requirement that the lower bound on the maximum mass of a compact star is $2 M_{\odot}$.