Neutron star properties, such as its mass, radius, and moment of inertia, are calculated by solving the Tolman-Oppenheimer-Volkov (TOV) equations using the ring-diagram equation of state (EOS) obtained from realistic low-momentum NN interactions $V_{low-k}$. Several NN potentials (CDBonn, Nijmegen, Argonne V18 and BonnA) have been employed to calculate the ring-diagram EOS where the particle-particle hole-hole ring diagrams are summed to all orders. The proton fractions for different radial regions of a $β$-stable neutron star are determined from the chemical potential conditions $μ_n-μ_p = μ_e = μ_μ$. The neutron star masses, radii and moments of inertia given by the above potentials all tend to be too small compared with the accepted values. Our results are largely improved with the inclusion of medium corrections based on Brown-Rho scaling where the in-medium meson masses, particularly those of $ω$, $ρ$ and $σ$, are slightly decreased compared with their in-vacuum values. Representative results using such medium corrected interactions are neutron star mass $M\sim 1.8 M_{\odot}$, radius $R\sim 9$ km and moment of inertia $\sim 60 M_{\odot}km^2$. The mass-radius trajectories given by the above four realistic NN potentials are by and large overlapping.
Core-polarization (CP) and Brown-Rho (BR) scaling were among Gerry's most favorite topics. In this contribution, we will discuss some of the early history as well as more recent work associated with these two fascinating phenomena. I (TTSK) will begin with some recollections of Princeton, where I met Gerry for the first time in 1964 and worked as his postdoc. Core polarization was in fact the first topic he assigned to me. JWH started working with Gerry at Stony Brook from 2003 and was Gerry's last student in nuclear physics. We three had teamed up well, working closely on both CP and BR scali…
We study the role of density-dependent low-momentum nucleon-nucleon interactions in describing the anomalously long beta decay lifetime of 14C. We approach this problem both from the perspective of chiral effective field theory, in which genuine three-body forces generate an effective density-dependent two-body interaction, as well as from the perspective of Brown-Rho scaling, in which the masses and form factor cutoffs in one-boson-exchange interactions are modified in a dense nuclear medium due to the partial restoration of chiral symmetry. The beta decay transition of 14C to the ground stat…
Sensitivity of neutron radii in the $"" sup 208_Pb nucleus and a neutron star to nucleon-$ sigma_-$ rho_ coupling corrections in relativistic mean field theory
Model-space effective interactions $V_{eff}$ derived from free-space nucleon-nucleon interactions $V_{NN}$ are reviewed. We employ a double decimation approach: first we extract a low-momentum interaction $V_{low-k}$ from $V_{NN}$ using a $T$-matrix equivalence decimation method. Then $V_{eff}$ is obtained from $V_{low-k}$ by way of a folded-diagram effective interaction method. For decimation momentum $Λ\simeq 2 fm^{-1}$, the $V_{low-k}$ interactions derived from different realistic $V_{NN}$ models are nearly model independent, and so are the resulting shell-model effective interactions. For …
We have calculated the nuclear symmetry energy $E_{sym}(ρ)$ up to densities of $4 \sim 5 ρ_0$ with the effects from the Brown-Rho (BR) and Ericson scalings for the in-medium mesons included. Using the $V_{low-k}$ low-momentum interaction with and without such scalings, the equations of state (EOS) of symmetric and asymmetric nuclear matter have been calculated using a ring-diagarm formalism where the particle-particle-hole-hole ring diagrams are included to all orders. The EOS for symmetric nuclear matter and neutron matter obtained with linear BR scaling are both overly stiff compared with th…
The medium modified hadron properties are studied by using the scale-chiral perturbation theory $χ$PT$_σ$ in which the lightest scalar meson $f_0(500)$ is included as an explicit degree of freedom by regarding it as the Nambu-Goldstone boson of scale symmetry both spontaneously broken and explicitly broken by the QCD trace anomaly. We derive Brown-Rho scaling at the leading order of scale symmetry from $χ$PT$_σ$ and formulate how to make higher-order scale-chiral corrections going beyond the leading order of scale symmetry. By taking into account the intrinsic density dependence given by the d…
The possibility of meson condensation in stars and in heavy-ion collisions has been discussed in the past. Here, we study whether rho meson condensation ($ρ^{-}$) can occur in very dense matter and determine the effect of strong magnetic fields on this condensation. We find that rho meson condensates can appear in the core of the neutron star assuming a rho mass which is reduced due to in-medium effects. We find that the magnetic field has a non-negligible effect in triggering condensation.
The explicit density (rho) dependence in the coupling coefficients of the non-relativistic nuclear energy-density functional (EDF) encodes effects of three-nucleon forces and dynamical correlations. The necessity for a coupling coefficient in the form of a small fractional power of rho is empirical and the power often chosen arbitrarily. Consequently, precision-oriented parameterisations risk overfitting and loss of predictive power. Observing that the Fermi momentum kF~rho^1/3 is a key variable in Fermi systems, we examine if a power hierarchy in kF can be inferred from the properties of homo…
Precision mass measurements of neutron-rich rhodium isotopes have been performed at the JYFLTRAP Penning trap mass spectrometer at the Ion Guide Isotope Separator On-Line (IGISOL) facility. We report results on ground- and isomeric-state masses in $^{110,112,114,116,118}$Rh and the very first mass measurement of $^{120}$Rh. The isomeric states were separated and measured for the first time using the phase-imaging ion-cyclotron-resonance (PI-ICR) technique. For $^{112}$Rh, we also report new half-lives for both the ground state and the isomer. The results are compared to theoretical predictions…
University of Wroclaw（弗罗茨瓦夫大学）；Helmholtz-Zentrum Dresden-Rossendorf (HZDR)（德累斯顿-罗斯多夫亥姆霍兹中心）；Center for Advanced Systems Understanding (CASUS)（先进系统理解中心）
The density dependence of the nuclear symmetry energy governs important aspects of very neutron rich systems such as heavy nuclei and their collisions, neutron stars and their mergers. Many analyses of experimental data have generated constraints on the symmetry energy and its first derivative at saturation density, rho_0 ~ 2.7xE14 g/cm3. We show that each analysis does not accurately constrain the symmetry energy at rho_0, but rather at a lower density, rho_s, that is most sensitively probed by that analysis. Using published constraints on the symmetry energy and its first derivative at rho_0…
Neutron-skin thickness of finite nuclei in relativistic mean-field models with chiral limits
利用相对论平均场拉格朗日量，根据高密度下手征对称性恢复的Brown-Rho标度，研究了有限核的几种结构性质.该模型是一致的，与目前的实验约束的对称物质的状态方程在正常和超常密度和非对称物质在亚饱和密度。结果表明，这些模型能成功地描述有限核的结合能和电荷半径。与通常的相对论平均场模型的计算结果相比，这些模型给出的^{208}Pb的中子皮厚度减小了0.17 fm ~ 0.21 fm。中子皮厚度的减小不仅是由于对称能的软化，而且还由于手征对称性的部分恢复所要求的$ρ$介子的标度性质。
We report Green's function Monte Carlo calculations of isospin-mixing (IM) matrix elements for the 2+, 1+, and 3+ T=0,1 pairs of states at 16--19 MeV excitation in 8Be. The realistic Argonne v18 (AV18) two-nucleon and Illinois-7 three-nucleon potentials are used to generate the nuclear wave functions. Contributions from the full electromagnetic interaction and strong class III charge-symmetry-breaking (CSB) components of the AV18 potential are evaluated. We also examine two theoretically more complete CSB potentials based on rho-omega mixing, tuned to give the same neutron-neutron scattering l…
We have studied the effect of free space nucleon radius on the nuclear matter and slowly rotating neutron star properties within a relativistic mean field model with the inclusion of omega-rho mixing nonlinear term. We use the same density dependent radius as in our previous work. However, in the present work we utilize the parameter sets with more proper symmetric nuclear matter (SNM) predictions for a number of different nucleon radii. To this end, the isoscalar parameters in each parameter set and the cutoff parameter $β$ are adjusted by fitting the corresponding SNM properties at sub-satur…
Using excitation energies to isobaric analog states (IAS) and charge invariance, we extract nuclear symmetry coefficients, from a mass formula, on a nucleus-by-nucleus basis. Consistently with charge invariance, the coefficients vary weakly across an isobaric chain. However, they change strongly with nuclear mass and range from a_a~10 MeV at mass A~10 to a_a~22 MeV at A~240. Following the considerations of a Hohenberg-Kohn functional for nuclear systems, we determine how to find in practice the symmetry coefficient using neutron and proton densities, even when those densities are simultaneousl…
At an hadronic scale the effect of CP-violating interactions that typically appear in extensions of the Standard Model may be described by an effective Lagrangian, in which the operators are expressed in terms of lepton and partonic gluon and quark fields, and ordered by their mass dimension, k .geq. 4. Using a global-symmetry-preserving truncation of QCD's Dyson-Schwinger equations, we compute the rho-meson's electric dipole moment (EDM), d_rho, as generated by the leading dimension-four and -five CP-violating operators and an example of a dimension-six four-quark operator. The two dimension-…
Within the Skyrme-Hartree-Fock (SHF) approach, we show that for a fixed mass number A, both the symmetry energy coefficient a_{sym}(A) in the semi-empirical mass formula and the nuclear matter symmetry energy E_{sym}(ρ_A) at a subsaturation reference density rho_A can be determined essentially by the symmetry energy E_{sym}(rho_0) and its density slope L at saturation density rho_0. Meanwhile, we find the dependence of a_{sym}(A) on E_{sym}(rho_0) or L is approximately linear and is very similar to the corresponding linear dependence displayed by E_{sym}(ρ_A), providing an explanation for the …
It is argued that a well measured double neutron star binary in which the two neutron stars are more than 4% different from each other in mass or a massive neutron star with mass M > 2 M_sun would put in serious doubt or simply falsify the following chain of predictions: (1) nearly vanishing vector meson mass at chiral restoration, (2) kaon condensation at a density n ~ 3 n_0, (3) the Brown-Bethe maximum neutron star mass M_max ~ 1.5 M_sun and (4) Smolin's `Cosmological Natural Selection' hypothesis.
