TY  - JOUR
A1  - Li, Jia Jie
A1  - Sedrakian, Armen
A1  - Weber, Fridolin
T1  - Competition between delta isobars and hyperons and properties of compact stars
T2  - Physics Letters B
N2  - The Δ-isobar degrees of freedom are included in the covariant density functional (CDF) theory to study the equation of state (EoS) and composition of dense matter in compact stars. In addition to Δ's we include the full octet of baryons, which allows us to study the interplay between the onset of delta isobars and hyperonic degrees of freedom. Using both the Hartree and Hartree–Fock approximation we find that Δ's appear already at densities slightly above the saturation density of nuclear matter for a wide range of the meson–Δ coupling constants. This delays the appearance of hyperons and significantly affects the gross properties of compact stars. Specifically, Δ's soften the EoS at low densities but stiffen it at high densities. This softening reduces the radius of a canonical 1.4M⊙ star by up to 2 km for a reasonably attractive Δ potential in matter, while the stiffening results in larger maximum masses of compact stars. We conclude that the hypernuclear CDF parametrizations that satisfy the 2M⊙ maximum mass constraint remain valid when Δ isobars are included, with the important consequence that the resulting stellar radii are shifted toward lower values, which is in agreement with the analysis of neutron star radii.
KW  - Equation of state
KW  - Dense matter
KW  - Delta resonance
KW  - Compact stars
Y1  - 2018
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/77437
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-774372
SN  - 0370-2693
VL  - 783
SP  - 234
EP  - 240
PB  - Elsevier
CY  - Amsterdam
ER  -