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The impact of the core mass on the compact/neutron-star mass-radius relation is studied. Besides the mass, the core is parameterized by its radius and surface pressure, which supports the outside one-component Standard Model (SM) matter. The core may accommodate SM matter with unspecified (or poorly known) equation-of-state or several components, e.g. consisting of admixtures of Dark Matter and/or Mirror World matter etc. beyond the SM. Thus, the admissible range of masses and radii of compact stars can be considerably extended., 20 pages, 9 figures, 1 table. Contribution to a Special Issue of PARTICLES: "Strong Interactions in the Standard Model: Massless Bosons to Compact Stars". Version accepted for publication. arXiv admin note: text overlap with arXiv:2203.17228

We argue for a continuous (dynamical) kinetic freeze-out of K &plusmn, ϕ observed at midrapidity in collisions of Au(1.23 A GeV) + Au. The simulations, by means of a transport model of Boltzmann-&Uuml, hling-Uhlenbeck (BUU) type, point to time independent transverse momentum slope parameters after 20 fm/c. The complex interplay of expansion dynamics and strangeness production/exchange/absorption as well as elastic scatterings involved in the reaction network does not support the previous interpretation of a late freeze-out of K &minus, due to larger cross sections.