Topology change and nuclear symmetry energy in compact-star matter

Liu, Xiang-Hai; Ma, Yong-Liang; Rho, Mannque

doi:10.1103/physrevc.99.055808

Cited by 7 publications

(6 citation statements)

References 45 publications

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“…This is because Σ = qq → 0 as n → n 1/2 . It has been shown [81] that the same cusp structure is obtained with the heavy vector degrees of freedom included in HLS Lagrangian. Just the location of the cusp changes with additional degrees of freedom, with the location tending to go to higher densities the more heavy degrees of freedom are included.…”

Section: Cusp In the Nuclear Symmetry Energymentioning

confidence: 56%

Towards the Hadron-Quark Continuity Via a Topology Change in Compact Stars

Ma,

Rho

2019

Preprint

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We review an effective field theory approach to dense compact-star matter that exploits the Cheshire Cat Principle for hadron-quark continuity at high density, adhering only to hadronic degrees of freedom, hidden topology and hidden symmetries of QCD. No Landau-Ginzburg-Wilsonian-type phase transition is involved in the range of densites involved. The microscopic degrees of freedom of QCD, i.e., quarks and gluons, possibly intervening at high baryonic density are traded in for fractionalized topological objects. Essential in the description are symmetries invisible in QCD in the matter-free vacuum: Scale symmetry, flavor local symmetry and parity-doubling. The partial emergence of scale symmetry is signaled by a dilatonic scalar in a "pseudo-conformal" structure. Flavor gauge symmetry manifests with the ρ meson mass going toward a Wilsonian RG fixed point identified with the "vector manifestation fixed point (VMFP)" at which the flavor gauge boson mass goes to zero. Parity doubling is to take place as the quasi-nucleon mass converges to the chiral invariant m 0 . The theory with a few controllable parameters accounts satisfactorily for all known properties of normal nuclear matter and makes certain predictions that are drastically different from what's available in the literature. In particular, it provides a topological mechanism, argued to be robust, for the cross-over from soft-to-hard equation of state that predicts the star properties in overall agreement with the presently available data, including the maximum star mass M max ∼ 2.3M and the recent LIGO/Virgo gravity-wave data. What is most glaringly different from all other approaches known, however, is the prediction for the rapid convergence to a sound velocity of star v 2 s ≈ 1/3 (in unit c = 1) at a density n ∼ > 3n 0 , far from the asymptotic density ∼ > 50n 0 expected in perturbative QCD. We interpret this to signal the precocious emergence in compact-star matter of a pseudo-conformal structure associated with the hidden symmetries.

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Section: Cusp In the Nuclear Symmetry Energymentioning

confidence: 56%

Towards the Hadron-Quark Continuity Via a Topology Change in Compact Stars

Ma,

Rho

2019

Preprint

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“…A surprising result found in [27] is that since Σ goes to zero as density approaches n 1/2 , there appears a cusp at n 1/2 , with the symmetry energy dropping going toward n 1/2 , then turning over and increasing as the density increases beyond n 1/2 . This cusp is highly robust against strong interactions [28] but, being semiclassical, is expected to be smoothed by higher order nuclear correlations. Also the pion mass will intervene in eliminating discontinuity in the cusp structure.…”

Section: Nuclear Symmetry Energymentioning

confidence: 98%

Pseudoconformal structure in dense baryonic matter

Rho

2019

Phys. Rev. D

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We clarify and extend further the idea we developed before that baryonic matter at high density has an emergent "pseudoconformal symmetry." It is argued that as baryonic density exceeds n ≃ n 1/2 > ∼ 2n0, a topology change mimicking the baryon-quark continuity takes place at n 1/2 . In terms of skyrmions, this corresponds to the transition from skyrmions to half-skyrmions and impacts on the equation of state of dense baryonic matter. The emergence in medium at n 1/2 of paritydoublet symmetry -which is invisible in QCD in a matter-free vacuum -plays the crucial role. The consequence of the topology change is that massive compact stars carry the "pseudoconformal sound velocity" v 2 s /c 2 ≈ 1/3 at n ∼ > n 1/2 signaling a precursor to the precocious emergence of scale symmetry as well as a local symmetry hidden in QCD in the matter-free vacuum. A highly significant prediction of this work is that the topology change density from normal matter to halfskyrmion matter, up to date inaccessible either by QCD proper or by terrestrial experiments, could possibly be pinned down within the range 2 < n 1/2 /n0 < 4, commensurate with the range expected for a continuous hadrons-to-quarks or -gluons transition.I.

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“…Based on what we discussed above and will develop below, it is found that the topology change is significant for developing the pseudo-conformal model (PCM) of dense nuclear matter, especially for the existence of the conformal sound velocity in compact star matter. Because of this topology change, there is a cusp structure in the symmetry energy E sym [11,89] which provides a simple mechanism for the putative soft-to-hard change in the EoS for compact stars at n ∼ 2n 0 needed to account for the observed massive ∼ 2M . In the models that resort to hadron-quark continuity in terms of specific quark degrees of freedom that are strongly coupled, the hardening of the EoS at n ∼ > 2n 0 is associated with "deconfinement" of quarks [4,23].…”

Section: Cheshire Cat Principle and Quark-hadron Continuitymentioning

confidence: 99%

Topology and emergent symmetries in dense compact star matter

Ma¹,

Yang²

2023

Preprint

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It has been found that the topology effect and the possible emergent scale and hidden local flavor symmetries at high density reveal a novel structure of the compact star matter. The N f ≥ 2 baryons can be described by the skyrmion in the large Nc limit and there is a robust topology change in the skyrmion matter approach to dense nuclear matter. The hidden scale and local flavor symmetries which are sources introducing the lightest scalar meson-dilaton-and lowest lying vector mesons into to nonlinear chiral effective theory are seen to play important roles in understanding the nuclear force. We review in this paper the generalized nuclear effective theory (GnEFT), which applicable to nuclear matter from low density to the compact star density, constructed with the robust conclusion from the topology approach to dense matter and emergent scale and hidden local flavor symmetries. The topology change at density larger than two times saturation density n0 encoded in the parameters of the effective field theory is interpreted as the hadron-quark continuity in the sense of Cheshire Cat Principle. A novel feature predicted in this theory that has not been found before is the precocious appearance of the conformal sound velocity in the cores of massive stars, although the trace of the energy-momentum tensor of the system is not zero. That is, in contrast to the usual picture, the cores of massive stars are composed of quasiparticles of fractional baryon charges, neither baryons nor deconfined quarks. Hidden scale and local flavor symmetries emerge and give rise a resolution of the longstanding gA quench problem in nuclei transition. To illustrate the rationality of the GnEFT, we finally confront the generalized effective field theory to the global properties of neutron star and the data from gravitational wave detections.

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Topology change and nuclear symmetry energy in compact-star matter

Cited by 7 publications

References 45 publications

Towards the Hadron-Quark Continuity Via a Topology Change in Compact Stars

Towards the Hadron-Quark Continuity Via a Topology Change in Compact Stars

Pseudoconformal structure in dense baryonic matter

Topology and emergent symmetries in dense compact star matter

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