Nuclear Theory·nucl-th

Tuesday·March 19, 2019

10 papers—9 primary·1 cross-listed

01
Vortices in low-density neutron matter and cold Fermi gases
Lucas Madeira · Stefano Gandolfi · Kevin E. Schmidt · Vanderlei S. Bagnato
Cold gas experiments can be tuned to achieve strongly-interacting regimes such as that of low-density neutron matter found in neutron-stars' crusts. We report $T$ =0 diffusion Monte Carlo results (i) for the ground state of both spin-1/2 fermions with short-range interactions and low-density neutron matter in a cylindrical container, and (ii) properties of these systems with a vortex line excitation. We calculate the equation of state for cold atoms and low-density neutron matter in the bulk systems, and we contrast it to our results in the cylindrical container. We compute the vortex line excitation energy for different interaction strengths, and we find agreement between cold gases and neutron matter for very low densities. We also calculate density profiles, which allow us to determine the density depletion at the vortex core, which depends strongly on the short-ranged interaction in cold atomic gases, but it is of $\approx$ 25% for neutron matter in the density regimes studied in this work. Our results can be used to constrain neutron matter properties by using measurements from cold Fermi gases experiments.
nucl-thcond-mat.quant-gasPRC(2019)·9 citations
02
From the microscopic to the macroscopic world: from nucleons to neutron stars
S. Gandolfi🇺🇸 · J. Lippuner🇺🇸 · A.W. Steiner🇺🇸 · I. Tews🇺🇸 · X. Du🇺🇸 · M. Al-Mamun🇺🇸
Recent observations of neutron-star properties, in particular the recent detection of gravitational waves emitted from binary neutron stars, GW 170817, open the way to put strong constraints on nuclear interactions. In this paper, we review the state of the art in calculating the equation of state of strongly interacting matter from first principle calculations starting from microscopic interactions among nucleons. We then review selected properties of neutron stars that can be directly compared with present and future observations.
nucl-thastro-ph.HEastro-ph.SRJ.Phys.G(2019)·40 citations
03
Massive Neutron Stars with a Color Superconducting Quark Matter Core
Takehiro Tanimoto🇯🇵 · Wolfgang Bentz🇯🇵 · Ian C. Cloët🇺🇸
We construct the equation of state for high density neutron star matter at zero temperature using the two-flavor Nambu--Jona-Lasinio (NJL) model as an effective theory of QCD. We build nuclear matter, quark matter, and the mixed phases from the same NJL Lagrangian, which has been used to model free and in-medium hadrons as well as nuclear systems. A focus here is to determine if the same coupling constants in the scalar diquark and vector meson channels, which give a good description of nucleon structure and nuclear matter, can also be used for the color superconducting high density quark matter phase. We find that this is possible for the scalar diquark (pairing) interaction, but the vector meson interaction has to be reduced so that superconducting quark matter becomes the stable phase at high densities. We compare our equation of state with recent phenomenological parametrizations based on generic stability conditions for neutron stars. We find that the maximum mass of a neutron star, with a color superconducting quark matter core, exceeds $2.01 \pm 0.04 M_{⊙}$ which is the value of the recently observed massive neutron star PSR J0348+0432. The mass-radius relation is also consistent with gravitational wave observations (GW170817).
nucl-thPRC(2020)·21 citations
04
A new analytical expression for calculation of the Coulomb potential in spherical nuclei
Hüseyin Koç · Erhan Eser · Cevad Selam
A lot of problems of atomic and nuclear physics depend on with high accuracy to the Coulomb potential. Therefore, it is very important to carefully and accurately calculate the Coulomb potential. In this study, a new analytical expression was obtained for calculating the Coulomb potential by choosing the Fermi distribution function, which is suitable for charge distribution in nuclei. The proposed formula guarantees an accurate and simple calculation of the Coulomb potential of nuclei. Using the analytical expression obtained, the Coulomb potentials for several spherical nuclei were calculated for all values of the parameters. It is shown that the results obtained for arbitrary values of the radius are consistent with the literature data. In this study, the accepted values in literature of the two parameters (Coulomb radius R_c and diffuseness parameter a_c) which are important for the coulomb potential are also discussed.
nucl-th0 citations
05
Toroidal states in $^{28}$ Si with covariant density functional theory in 3D lattice space
Z. X. Ren🇨🇳 · P. W. Zhao · S. Q. Zhang · J. Meng
The toroidal states in $^{28}$ Si with spin extending to extremely high are investigated with the cranking covariant density functional theory on a 3D lattice. Thirteen toroidal states with spin $I$ ranging from 0 to 56 $ℏ$ are obtained, and their stabilities against particle emissions are studied by analyzing the density distributions and potentials. The excitation energies of the toroidal states at $I = 28$ , 36, 44 $ℏ$ reasonably reproduce the observed three resonances extracted from the 7- $α$ de-excitation of $^{28}$ Si. The $α$ clustering of these toroidal states is supported by the $α$ -localization function.
nucl-thnucl-exNPA(2020)·32 citations
06
Systematic study of $α$ decay for odd- $A$ nuclei within a two-potential approach
Xiao-Dong Sun · Chao Duan · Jun-Gang Deng · Ping Guo · Xiao-Hua Li
$α$ decay is usually associated with both ground and low-lying isomeric states of heavy and superheavy nuclei, and the unpaired nucleon plays a key role on $α$ decay. In this work, we systematically studied the $α$ decay half-lives of odd- $A$ nuclei, including both favored and unfavored $α$ decay within the two-potential approach based on the isospin dependent nuclear potential. The $α$ preformation probabilities are estimated by using an analytic formula taking into account the shell structure and proton-neutron correlation, and the parameters are obtained through the $α$ decay half-lives data. The results indicate that in general the $α$ preformation probabilities of even- $Z$ , odd- $N$ nuclei are slightly smaller than the odd- $Z$ , even- $N$ ones. We found that the odd-even staggering effect may play a more important role on spontaneous fission than $α$ decay. The calculated half-lives can well reproduce the experimental data.
nucl-thPRC(2017)·51 citations
07
Structure, formation and decay of $K ˉ N N$ system by Faddeev-AGS calculations
Sajjad Marri🇮🇷 · S. Z. Kalantari🇮🇷 · J. Esmaili🇮🇷
The Faddeev AGS equations are solved for coupled-channels $K ˉ N N - π Σ N$ system with quantum numbers $I = 1/2$ and $S = 0$ . Using separable potentials for $K ˉ N - π Σ$ interaction, we have calculated the transition probability for the $(Y_{K})_{I = 0} + N \to π Σ N$ reaction. The possibility to observe the trace of $K^{-} pp$ quasi-bound state in the $π Σ N$ mass spectra was studied. Various types of chiral based and phenomenological potentials are used to describe the $K ˉ N - π Σ$ interaction. It was shown that not only we can see the signature of the $K^{-} pp$ quasi-bound state in the mass spectra, but also, one can see the trace of branch points in the observables.
nucl-thCPC(2019)·6 citations
08
Proof by characters of the orthogonal-orthogonal duality and relations of Casimir invariants
K. Neergård
The theorem of orthogonal-orthogonal duality of Rowe, Repka, and Carvalho is proven by a method based on characters that is very different from theirs and akin to Helmers's half a century earlier proof of the analogous sympletic-symplectic duality. I demonstrate how three duality theorems listed by Rowe, Repka, and Carvalho allow very brief derivations of linear relations between the Casimir invariants of the connected representations based on the geometry of their Young diagrams, and discuss for which physical systems other than such already considered in the literature an analysis in terms of the orthogonal-orthogonal duality might be useful.
nucl-thJ.Math.Phys.(2019)·5 citations
09
Naive versus mirror assignment at finite density: correlator mixing and chiral symmetry restoration
Boris Krippa🇬🇧
Chiral symmetry imposes some constrains on hadron correlation functions in dense medium. These constraints imply a certain general structure of the two- and three-point correlation functions of chiral partners and lead to the effect of mixing arising from the interaction of the long-ranged nuclear pions with corresponding interpolating currents. It reflects the phenomena of partial restoration of chiral symmetry. We consider soft pion corrections for quark condensates and several possible pairs of chiral partners for both mesons and nucleons and analyse their mixing patterns. We explored both naive and mirror assignments for the chiral partner of nucleon and discussed possible phenomenological consequence.
nucl-thhep-phJ.Phys.G(2020)·0 citations

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first authorsco-authorsvia INSPIRE