The Nuclear Matter Density Functional under the Nucleonic Hypothesis

A Bayesian analysis of the possible behaviors of the dense matter equation of state informed by recent LIGO-Virgo as well as NICER measurements reveals that all the present observations are compatible with a fully nucleonic hypothesis for the composition of dense matter, even in the core of the most massive pulsar PSR J0740+6620. Under the hypothesis of a nucleonic composition, we extract the most general behavior of the energy per particle of symmetric matter and density dependence of the symmetry energy, compatible with the astrophysical observations as well as our present knowledge of low-energy nuclear physics from effective field theory predictions and experimental nuclear mass data. These results can be used as a null hypothesis to be confronted with future constraints on dense matter to search for possible exotic degrees of freedom.

Manifestation of hidden symmetries in baryonic matter: From finite nuclei to neutron stars

When hadron-quark continuity is formulated in terms of a topology change at a density higher than twice the nuclear matter density [Formula: see text], the core of massive compact stars can be described in terms of quasiparticles of fractional baryon charges, behaving neither like pure baryons nor like deconfined quarks. Hidden symmetries, both local gauge and pseudo-conformal (or broken scale), emerge and give rise both to the long-standing “effective [Formula: see text]” in nuclear Gamow–Teller (GT) transitions at [Formula: see text] and to the pseudo-conformal sound velocity [Formula: see text] at [Formula: see text]. It is suggested that what has been referred to, since a long time, as “quenched [Formula: see text]” in light nuclei reflects what leads to the dilaton-limit [Formula: see text] at near the (putative) infrared fixed point of scale invariance. These properties are confronted with the recent observations in GT transitions and in astrophysical observations.

A bridge between finite and infinite Nuclear matter

The bridge between finite and infinite nuclear system is analyzed for the fundamental quantities such as binding energy, incompressibility and giant monopole excitation energy using relativistic mean-field formalism. The well known Thomas-Fermi, extended Thomas-Fermi and Hartree approximations are used to evaluate the observables. A parametric form of the density is used to convert the infinite nuclear matter density to the mean density of a finite nucleus. The present analysis shows an estimation of finite nucleus properties from information of the corresponding infinite nuclear matter quantities only approximately. In other words, it is not quite obvious to get the observables of finite nuclei by converting the corresponding entities of the nuclear matter system or vice versa. If at all one can achieved, it can be done only approximately.

A nuclear matter calculation with the tensor-optimized Fermi sphere method with central interaction

The tensor-optimized Fermi sphere (TOFS) theory is applied first for the study of the property of nuclear matter using the Argonne V4$^\prime$$NN$ potential. In the TOFS theory, the correlated nuclear matter wave function is taken to be a power-series type of the correlation function $F$, where $F$ can induce central, spin–isospin, tensor, etc. correlations. This expression has been ensured by a linked cluster expansion theorem established in the TOFS theory. We take into account the contributions from all the many-body terms arising from the product of the nuclear matter Hamiltonian $\mathcal{H}$ and $F$. The correlation function is optimally determined in the variation of the total energy of nuclear matter. It is found that the density dependence of the energy per particle in nuclear matter is reasonably reproduced up to the nuclear matter density $\rho \simeq 0.20$ fm$^{-3}$ in the present numerical calculation, in comparison with other methods such as the Brueckner–Hartree–Fock approach.

Puzzle of the folding potential on the nuclear halo reactions

Folding potentials of the elastic scattering drip-line nuclei at various incident energies is one method to study nuclear matter density distributions and nuclear radii. The nuclei with density distributions consisting of a bulk (core) and an outer layer (halo), dilute and spatially extended are called the halo nuclei caused for the weak particle binding. Several halo nuclei are studied and many potential candidates are identified. All the cross-sections of the elastic scattering for the drip-line nuclei 11 Be and 6 He , are calculated to understand the exotic properties of these nuclei starting from its structure, extended radius, nuclear size till the large total reaction cross-sections for these nuclei when it interact with a stable target 12 C .

Thermal conductivity of the quark matter for the SU(2) light-flavor sector

We investigate the thermal conductivity (κ) of the quark matter at finite quark chemical potential (μ) and temperature (T), employing the Green–Kubo formula, for the SU(2) light-flavor sector with the finite current-quark mass m = 5 MeV . As a theoretical framework, we construct an effective thermodynamic potential from the (μ, T)-modified liquid-instanton model (mLIM). Note that all the relevant model parameters are designated as functions of T, using the trivial-holonomy caloron solution. By solving the self-consistent equation of mLIM, we acquire the constituent-quark mass M0 as a function of T and μ, satisfying the universal-class patterns of the chiral phase transition. From the numerical results for κ, we observe that there emerges a peak at μ≈200 MeV for the low-T region, i.e. T≲100 MeV . As T increase over T≈100 MeV , the curve for κ is almost saturated as a function of T in the order of ~ 10-1 GeV 2, and grows with respect to μ smoothly. At the normal nuclear-matter density ρ0 = 0.17 fm -3, κ shows its maximum 6.22 GeV 2 at T≈10 MeV , then decreases exponentially down to κ≈0.2 GeV 2. We also compute the ratio of κ and the entropy density, i.e. κ/s as a function of (μ, T) which is a monotonically decreasing function for a wide range of T, then approaches a lower bound at very high T: κ/s min ≳0.3 GeV -1 in the vicinity of μ = 0.

SPIN POLARIZATION IN HIGH DENSITY QUARK MATTER

We investigate the occurrence of a ferromagnetic phase transition in high density hadronic matter (e.g., in the interior of a neutron star). This could be induced by a four-fermion interaction analogous to the one which is responsible for chiral symmetry breaking in the Nambu–Jona-Lasinio model, to which it is related through a Fierz transformation. Flavor SU(2) and flavor SU(3) quark matter are considered. A second-order phase transition is predicted at densities about 5 times the normal nuclear matter density. It is also found that in flavor SU(3) quark matter, a first-order transition from the so-called 2 flavor super-conducting phase to the ferromagnetic phase arises. The color-flavor-locked phase may be completely hidden by the FP.