Flavor Symmetry and Topology Change in Nuclear Symmetry Energy for Compact Stars

Abstract

The nuclear symmetry energy figures crucially in the structure of asymmetric nuclei and, more importantly, in the equation of state (EoS) of compact stars. At present it is almost totally unknown, both experimentally and theoretically, in the density regime appropriate for the interior of neutron stars. Basing on a strong-coupled structure of dense baryonic matter encoded in the skyrmion crystal approach with a topology change and resorting to the notion of generalized hidden local symmetry in hadronic interactions, we address a variety of hitherto unexplored issues of nuclear interactions associated with the symmetry energy, i.e., kaon condensation and hyperons, possible topology change in dense matter, nuclear tensor forces, conformal symmetry, chiral symmetry, etc., in the EoS of dense compact-star matter. One of the surprising results coming from HLS structure that is distinct from what is given by standard phenomenological approaches is that at high density, baryonic matter is driven by renormalization group flow to the "dilaton-limit fixed point" constrained by "mended symmetries". We further propose how to formulate kaon condensation and hyperons in compact-star matter in a framework anchored on a single effective Lagrangian by treating hyperons as the Callan-Klebanov kaon-skyrmion bound states simulated on crystal lattice. This formulation suggests that hyperons can figure in the stellar matter -if at allwhen or after kaons condense, in contrast to the standard phenomenological approaches where the hyperons appear as the first strangeness degree of freedom in matter, thereby suppressing or delaying kaon condensation. In our simplified description of the stellar structure in terms of symmetry energies, which is compatible with that of the 1.97 solar mass star, kaon condensation plays a role of "doorway state" to strange quark matter. stars stable against collapse to black holes, can be addressed in terms of the nuclear symmetry energy ǫ sym . How nuclear forces mediating the strong interactions and controlling the phase structure of multi-baryonic systems enter into the nature of ǫ sym , presumably controlling the fate of compacts stars, is one of the principal themes of our current theoretical research into baryonic matter at high density. This note is a sequel to, and a substantial updating of, previous reports. 1,2On the experimental side, there are broadly two avenues, namely, terrestrial laboratories and space observatories. The heavy-ion collision is one of the terrestrial tools to gain information on how the strong interactions between hadrons (nuclear interaction) are modified with varying densities. In project are laboratories such as KoRIA (Korean Rare Isotope Accelerator, officially called "RAON") and other RIB machines, FAIR (Facility for Antiproton and Ion Reactions) at GSI/Darmstadt, FRIB (Facility for Rare Isotope Beams) at MSU/Michigan and NICA (Nuclotron-based Ion Collider Facility) at JINR/Dubna. They will probe the ranges of temperature up to 50-60 MeV and of density up to (3-4)n 0 (wher...

Compact star matter: EoS with new scaling law

“…To cover both regimes in a consistent way in a unified field theoretic approach seems like a tall order. In this work, we discuss the physical properties of stellar matter using the newly proposed scheme of a new scaling law(BLPR) in medium 7,8 all the way from normal nuclear density up to the higher density at the core of a neutron star. With a confrontation with the observed massive stars 4 , we discuss the physical properties of stellar matter with the EoS obtained therein.…”

Topology change and tensor forces for the EoS of dense baryonic matter

“…The modifications come only for density n ≥ n 1/2 , with the properties below n 1/2 being essentially the same as in [26]. Since the new BR we have here is gotten from recent developments that involve also Byung-Yoon Park (skyrmion crystal) and Hyun Kyu Lee (dilaton), following [27], we refer to this new BR as "BLPR scaling." We will argue that the translation of the topology change into parameter change of the Lagrangian has a support in the structure of the symmetry energy.…”

The Influence of the Symmetry Energy on the Structure of Hyperon Stars

“…is a function of baryon number density n B and the asymmetry parameter δ a ; E(n B , δ a ) in equation 2denotes the total energy of the nuclear system. Considering the model of nuclear matter consisting of N nucleons, the symmetry energy provides basic information about energy difference between states with different neutron-proton asymmetry and is defined as the energy difference of the state with specified proton and neutron composition, and the one with equal number of neutrons and protons (symmetric nuclear matter) and can be written as [3]:…”