Imprints of Nuclear Symmetry Energy on Properties of Neutron Stars

Li, Bao-An; Chen, Lie‐Wen; Gearheart, Michael; Hooker, J.; Ko, Che Ming; Krastev, Plamen G.; Lin, Weikang; Newton, William; Wang, Dehua; Xu, Chang; Xu, Jun

doi:10.1088/1742-6596/312/4/042006

Cited by 17 publications

(22 citation statements)

References 108 publications

(126 reference statements)

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“…(8) to extract the symmetry energy as defined in Eq. (3). There then will be the trivial kinematic correction coming from the three-momentum dependence in the kinetic energy part of Eq.…”

Section: Results For the Nucleon Sum Rule And The Nuclear Symmetrmentioning

confidence: 99%

“…For m q = 5 MeV, we have qq vac = −(263 MeV) 3 . Likewise, we will further assume that the ratios between the isospin singlet and triplet operators remain the same for all two quark operator expectation values with any number of covariant derivatives inserted:…”

Section: B Condensates In the Asymmetric Nuclear Mediummentioning

confidence: 99%

“…Understanding the details of the nuclear symmetry energy is intricately related to understanding a wide range of subjects ranging from rare isotopes to neutron rich nuclear matter such as the neutron star [2,3]. One of the main puzzle to be solved currently is the behavior of the nuclear symmetry energy at high density [4,5].…”

Section: Introductionmentioning

confidence: 99%

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Nuclear symmetry energy from QCD sum rules

Jeong

Lee

2013

Phys. Rev. C

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We calculate the nucleon self-energies in isospin-asymmetric nuclear matter using QCD sum rules. Taking the difference of these for the neutron and proton enables us to express the potential part of the nuclear symmetry energy in terms of local operators. We find that the scalar (vector) self energy part gives a negative (positive) contribution to the nuclear symmetry energy which is consistent with the results from relativistic mean field theories. Moreover, we find that an important contribution to the negative contribution of the scalar self energy comes from the twist-4 matrix elements, whose leading density dependence can be extracted from deep inelastic scattering experiments. This suggests that the twist-4 contribution partly mimics the exchange of the δ meson and that it constitutes an essential part in the origin of the nuclear symmetry energy from QCD. Our result also extends an early success of QCD sum rule method in understanding the symmetric nuclear matter in terms of QCD variables to the asymmetric nuclear matter case.

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“…(8) to extract the symmetry energy as defined in Eq. (3). There then will be the trivial kinematic correction coming from the three-momentum dependence in the kinetic energy part of Eq.…”

Section: Results For the Nucleon Sum Rule And The Nuclear Symmetrmentioning

confidence: 99%

Section: B Condensates In the Asymmetric Nuclear Mediummentioning

confidence: 99%

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Nuclear symmetry energy from QCD sum rules

Jeong

Lee

2013

Phys. Rev. C

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“…[5], named in SET2 as MIX1b, and, for the sake of completeness, we also compare the new range of L 0 with a combination of the ranges recently given in Refs. [18,66]. We name this more restrictive range for L 0 , namely, 30 L 0 80 MeV, as MIX2b.…”

Section: B Updated Constraints: Set2a and Set2bmentioning

confidence: 99%

Relativistic mean-field hadronic models under nuclear matter constraints

et al. 2014

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Background:The microscopic composition and properties of infinite hadronic matter at a wide range of densities and temperatures have been subjects of intense investigation for decades. The equation of state (EoS) relating pressure, energy density, and temperature at a given particle number density is essential for modeling compact astrophysical objects such as neutron stars, core-collapse supernovae, and related phenomena, including the creation of chemical elements in the universe. The EoS depends not only on the particles present in the matter, but, more importantly, also on the forces acting among them. Because a realistic and quantitative description of infinite hadronic matter and nuclei from first principles in not available at present, a large variety of phenomenological models has been developed in the past several decades, but the scarcity of experimental and observational data does not allow a unique determination of the adjustable parameters. Purpose: It is essential for further development of the field to determine the most realistic parameter sets and to use them consistently. Recently, a set of constraints on properties of nuclear matter was formed and the performance of 240 nonrelativistic Skyrme parametrizations was assessed [M. Dutra et al., Phys. Rev. C 85, 035201 (2012)] in describing nuclear matter up to about three times nuclear saturation density. In the present work we examine 263 relativistic-mean-field (RMF) models in a comparable approach. These models have been widely used because of several important aspects not always present in nonrelativistic models, such as intrinsic Lorentz covariance, automatic inclusion of spin, appropriate saturation mechanism for nuclear matter, causality, and, therefore, no problems related to superluminal speed of sound in medium. Method: Three different sets of constraints related to symmetric nuclear matter, pure neutron matter, symmetry energy, and its derivatives were used. The first set (SET1) was the same as used in assessing the Skyrme parametrizations. The second and third sets (SET2a and SET2b) were more suitable for analysis of RMF and included, up-to-date theoretical, experimental and empirical information. Results: The sets of updated constraints (SET2a and SET2b) differed somewhat in the level of restriction but still yielded only 4 and 3 approved RMF models, respectively. A similarly small number of approved Skyrme parametrizations were found in the previous study with Skyrme models. An interesting feature of our analysis 0556-2813/2014/90(5)/055203 (35) 055203-1 ©2014 American Physical Society M. DUTRA et al.PHYSICAL REVIEW C 90, 055203 (2014) has been that the results change dramatically if the constraint on the volume part of the isospin incompressibility (K τ,v ) is eliminated. In this case, we have 35 approved models in SET2a and 30 in SET2b. Conclusions: Our work provides a new insight into application of RMF models to properties of nuclear matter and brings into focus their problematic proliferation. The assessment performed in this wo...

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“…The remaining three are not nearly so well known: The nuclear incompressibility K is thought to lie between 200 and 300 MeV, with many authors placing it in the range 240 ± 10 MeV (see [60] is the average of the neutron and proton masses.) The symmetry energy a sym is thought to lie between 28 and 34 MeV (see Li et al [61] gives the masses of stars that first contain hybrid matter; R hybrid max /R denotes the maximum radius fraction occupied by hybrid matter (i.e., the radius fraction for the maximum mass star); and Cmax denotes the maximum compactness (2GM/Rc 2 ) of a star. We also give the composition of the rare phase ("Q" for quark and "H" for hadronic) and the dimension of the lattice at the center of the maximum mass star.…”

Section: Mixed Phasementioning

confidence: 99%

Shear modulus of the hadron-quark mixed phase

Johnson-McDaniel

Owen

2012

Phys. Rev. D

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Robust arguments predict that a hadron-quark mixed phase may exist in the cores of some "neutron" stars. Such a phase forms a crystalline lattice with a shear modulus higher than that of the crust due to the high density and charge separation, even allowing for the effects of charge screening. This may lead to strong continuous gravitational-wave emission from rapidly rotating neutron stars and gravitational-wave bursts associated with magnetar flares and pulsar glitches. We present the first detailed calculation of the shear modulus of the mixed phase. We describe the quark phase using the bag model plus first-order quantum chromodynamics corrections and the hadronic phase using relativistic mean-field models with parameters allowed by the most massive pulsar. Most of the calculation involves treating the "pasta phases" of the lattice via dimensional continuation, and we give a general method for computing dimensionally continued lattice sums including the Debye model of charge screening. We compute all the shear components of the elastic modulus tensor and angle average them to obtain the effective (scalar) shear modulus for the case where the mixed phase is a polycrystal. We include the contributions from changing the cell size, which are necessary for the stability of the lower-dimensional portions of the lattice. Stability also requires a minimum surface tension, generally tens of MeV fm −2 depending on the equation of state. We find that the shear modulus can be a few times 10 33 erg cm −3 , two orders of magnitude higher than the first estimate, over a significant fraction of the maximum mass stable star for certain parameter choices.

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Imprints of Nuclear Symmetry Energy on Properties of Neutron Stars

Cited by 17 publications

References 108 publications

Nuclear symmetry energy from QCD sum rules

Nuclear symmetry energy from QCD sum rules

Relativistic mean-field hadronic models under nuclear matter constraints

Shear modulus of the hadron-quark mixed phase

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