Nuclear Theory·nucl-th

Thursday·January 19, 2023

9 papers—7 primary·2 cross-listed

01
The mass of charged pions in neutron star matter
Bryce Fore · Norbert Kaiser · Sanjay Reddy · Neill C. Warrington
We examine the behavior of charged pions in neutron-rich matter using heavy-baryon chiral perturbation theory. This study is motivated by the prospect that pions, or pion-like excitations, may be relevant in neutron-rich matter encountered in core-collapse supernovae and neutron star mergers. We find, as previously expected, that the $π^{-}$ mass increases with density and precludes s-wave condensation at $n_{B} ≲ n_{sat}$ , where $n_{sat} ≃ 0.16 fm^{- 3}$ is the nuclear saturation density, and the mass of the $π^{+}$ mode decreases with density. The uncertainty in these predictions increases rapidly for $n_{B} ≳ n_{sat}$ because low energy constants associated with the two-pion-two-nucleon operators in chiral perturbation theory are poorly constrained. We find that these uncertainties are especially large in symmetric nuclear matter and should be included in the analysis of pion-nucleus interactions at low energy and pionic atoms. In neutron-rich matter, accounting for the self-energy difference between neutrons and protons related to the nuclear symmetry energy has several effects. It alters the power counting of certain higher-order contributions to the pion self-energy. Previously unimportant but attractive diagrams are enhanced and result in a modest reduction of the pion masses. Furthermore, in the low-wavelength limit, a collective mode with the quantum numbers of the $π^{+}$ appears.
nucl-thastro-ph.HEhep-phPRC(2024)·27 citations
02
Systematic study for relation between nuclear structure and reaction in $^{10}$ Be nucleus
T. Furumoto · T. Suhara · N. Itagaki
We systematically investigate the relation between the nuclear structure and reaction in the $^{10}$ Be nucleus using a theoretical framework. The structure of the $^{10}$ Be nucleus is constructed with a cluster model based on a microscopic viewpoint. In this paper, the $^{10}$ Be nucleus with different structures is prepared by manipulating the parameters of an effective nucleon-nucleon interaction. The nuclear structure and expectation values of physical quantities are drastically changed by the modification. We summarize such changes and show the effects on the elastic and inelastic scatterings for the proton and $^{12}$ C targets in the microscopic coupled-channel calculation. Especially, we recently reported the visualization of dineutron correlation in $^{10}$ Be on proton inelastic scattering in [Phys. Rev. C104, 034613 (2021)]. In this preceding work, we found that the changing the degree of dineutron correlation in $^{10}$ Be leads to drastic changes of the inelastic cross section for the 2 $_{2}^{+}$ state. The development (or breaking) of the dineutron correlation is governed by the strength of the spin-orbit interaction of the structure calculation. However, in the previous work, some of the realistic physical points were missing, for example, the binding energy. Therefore, we reconstruct the $^{10}$ Be nucleus by adjusting the effective nucleon-nucleon interaction to obtain the reasonable binding energy of the ground state. With this improvement, we again discuss the dineutron correlation in the $^{10}$ Be nucleus. We reconfirm the way to measure the degree of the development (or breaking) of dineutron cluster structure; the sensitivity to the inelastic cross section of the ground state to the 2 $_{2}^{+}$ state of $^{10}$ Be.
nucl-thnucl-exPTEP(2023)·2 citations
03
Three-body coupled channel framework for two-neutron halo nuclei
Jin-Yi Pang · Li-Tan Li · Feng-Kun Guo · Jia-Jun Wu
We study the Borromean nuclei formed by a core nucleus and two neutrons in a nonrelativistic effective field theory formalism considering both neutron-neutron and neutron-core interactions. We provide formulae of the charge and matter radii, and successfully reproduce the universal relation proposed by Hongo and Son based on the approximation of an infinite neutron-neutron scattering length and neglecting the neutron-core scattering. Once the realistic finite neutron-neutron and neutron-core scattering lengths are used, the charge and matter radii are influenced by the neutron-core channel in a growingly relevant manner. We obtain a relation among the binding energy of the three-body Borromean system, the ratio between charge and matter radii, and the ratio between the neutron-neutron and core-neutron scattering lengths. We find that the two-neutron separation energy for $^{22}$ C needs to be $≲ 2$ keV in order to be consistent with the experimental constraints of the matter radius of $^{22}$ C and the $^{20} C n$ $S$ -wave scattering length.
nucl-thhep-phnucl-ex2 citations
04
The Self-energy of Nucleon for the Photoproduction of Pion in the Low-energy Region
Susumu Kinpara🇯🇵
The scattering amplitude of the photoproduction of $π^{+}$ is calculated using the helicity formalism. The pseudovector coupling $π$ -N interaction with the non-perturbative term is applied to the perturbative expansion. The parameters for the self-energy are taken from the results of the $π$ -N scattering in our previous study.
nucl-th0 citations
05
Three-body calculations of beta decay applied to $^{11}$ Li
E. Garrido · A.S. Jensen · H.O.U. Fynbo · K. Riisager
A novel practical few-body method is formulated to include isospin symmetry for nuclear halo structures. The method is designed to describe beta decay, where the basic concept of isospin symmetry facilitates a proper understanding. Both isobaric analogue and anti-analogue states are treated. We derive general and explicit formulas for three-body systems using hyperspherical coordinates. The example of the beta decaying $^{11}$ Li ( $^{9}$ Li+ $n$ + $n$ ) is chosen as a challenging application for numerical calculations of practical interest. The detailed results are compared to existing experimental data and good agreement is found at high excitation energies, where the isobaric analogue and anti-analogue states are situated in the daughter nucleus. An interpretation of the decay pattern at lower excitation energies is suggested. Decays of the $^{9}$ Li-core and the two halo-neutrons are individually treated and combined to the daughter system with almost unique isospin, which we predict to be broken by about $0.4%$ probability. Properties of decay products are predicted as possible future tests of this model.
nucl-thnucl-exPRC(2023)·1 citation
06
Isoscalar Giant Monopole Resonance in Spherical Nuclei as a Nuclear Matter Incompressibility Indicator
M.K. Gaidarov · M.V. Ivanov · Y.I. Katsarov · A.N. Antonov
The incompressibility of both nuclear matter and finite nuclei is estimated by the monopole compression modes in nuclei in the framework of a nonrelativistic Hartree-Fock-Bogoliyubov method and the coherent density fluctuation model. The monopole states originate from vibrations of the nuclear density. The calculations in the model for the incompressibility in finite nuclei are based on the Brueckner energy-density functional for nuclear matter. Results for the energies of the breathing vibrational states and finite nuclei incompressibilities are obtained for various nuclei and their values are compared with recent experimental data. The evolution of the isoscalar giant monopole resonance (ISGMR) along Ni, Sn, and Pb isotopic chains is discussed. This approach can be applied to analyses of neutron stars properties, such as incompressibility, symmetry energy, slope parameter, and other astrophysical quantities, as well as for modelling dynamical behaviors within stellar environments.
nucl-thAstronomy(2023)·7 citations
07
Revisiting the stability of strange-dwarf stars and strange planets
Victor P. Goncalves · Jose C. Jimenez · Lucas Lazzari
The dynamical stability of strange-dwarf hybrid stars and strange planets, constituted by strange-quark-matter cores and dilute-nuclear-matter crusts, is revisited by analyzing the fundamental mode eigenfrequencies of the radial oscillation equations with boundary conditions for slow (rapid) conversions originating at the density-discontinuous interface characterizing extremely large (small) microscopic timescales compared to the oscillation periods. For the hadronic crust we used an analytic fit of the BPS results matched to the massless MIT bag model. For the rapid case, our calculations indicate that the zero mode is the so-called {\it reaction mode} whose frequency is a complex number, thus ruling out the existence of strange dwarfs (planets) in nature. On the other hand, slow conversions still provide a sizeable stability window which, interestingly, also reproduces the Glendenning-Kettner-Weber results. The robustness of our findings is demonstrated for different transition densities and using an equation of state from perturbative QCD for the ultra-dense core.
nucl-thastro-ph.SRhep-phEPJA(2023)·7 citations

Affiliations

first authorsco-authorsvia INSPIRE

The mass of charged pions in neutron star matter

Systematic study for relation between nuclear structure and reaction in 10Be nucleus

Three-body coupled channel framework for two-neutron halo nuclei

The Self-energy of Nucleon for the Photoproduction of Pion in the Low-energy Region

Three-body calculations of beta decay applied to 11Li

Isoscalar Giant Monopole Resonance in Spherical Nuclei as a Nuclear Matter Incompressibility Indicator

Revisiting the stability of strange-dwarf stars and strange planets

Affiliations

Systematic study for relation between nuclear structure and reaction in $^{10}$ Be nucleus

Three-body calculations of beta decay applied to $^{11}$ Li