Nuclear Theory·nucl-th

Tuesday·August 4, 2020

17 papers—8 primary·9 cross-listed

01
The nuclear symmetry energy from neutron skins and pure neutron matter in a Bayesian framework
William G. Newton · Gabriel Crocombe
We present an inference of the nuclear symmetry energy magnitude $J$ , the slope $L$ and the curvature $K_{sym}$ by combining neutron skin data on Ca, Pb and Sn isotopes and our best theoretical information about pure neutron matter (PNM). A Bayesian framework is used to consistently incorporate prior knowledge of the PNM equation of state from chiral effective field theory calculations. Neutron skins are modeled in a Hartree-Fock approach using an extended Skyrme energy-density functional which allows for independent variation of $J$ , $L$ and $K_{sym}$ without affecting the symmetric nuclear matter equation of state. We discuss the choice of neutron skin data sets, and combining errors in quadrature we obtain 95\% credible values of $J = 31.3 + 4.2 - 5.9$ MeV, $L = 40 + 34 - 26$ MeV and $K_{τ} = L - 6 K_{sym} = - 444 + 100 - 84$ MeV using uninformative priors in $J$ , $L$ and $K_{sym}$ , and $J = 31.9 + 1.3 - 1.3$ MeV, $L = 37 + 9 - 8$ MeV and $K_{τ} = - 480 + 25 - 26$ MeV using PNM priors. The correlations between symmetry energy parameters induced by neutron skin data is discussed and compared with the droplet model. Neutron skin data alone is shown to place limits on the symmetry energy parameters as stringent as those obtained from chiral effective field theory alone, and when combined the 95\% credible intervals are reduced by a factor of 4-5. Ahead of new measurements of lead and calcium neutron skins from parity-violating electron scattering experiments at Jefferson Lab and Mainz Superconducting Accelerator, we make predictions based on existing data on neutron skins of tin for the neutron skins of calcium and lead of 0.166 $\pm$ 0.008 fm and $0.169 \pm 0.014$ fm respectively, using uninformative priors, and 0.167 $\pm$ 0.008 fm and $0.172 \pm 0.015$ fm respectively, using PNM priors.
nucl-thastro-ph.HEPRC(2021)·40 citations
02
Three-body model for $K (1460)$ resonance
I. Filikhin🇺🇸 · R. Ya. Kezerashvili🇺🇸 · V. M. Suslov🇺🇸 · Sh. M. Tsiklauri🇺🇸 · B. Vlahovic🇺🇸
The three-body $K K K ˉ$ model for the $K (1460)$ resonance is developed on the basis of the Faddeev equations in configuration space. A single-channel approach is using with taking into account the difference of masses of neutral and charged kaons. It is demonstrated that a splitting the mass of the $K (1460)$ resonance takes a place around 1460 MeV according to $K^{0} K^{0} K ˉ^{0}$ , $K^{0} K^{+} K^{-}$ and $K^{+} K^{0} K ˉ^{0}$ , $K^{+} K^{+} K^{-}$ neutral and charged particle configurations, respectively. The calculations are performed with two sets of $K K$ and $K K ˉ$ phenomenological potentials, where the latter interaction is considered the same for the isospin singlet and triplet states. The effect of repulsion of the $K K$ interaction on the mass of the $K K K ˉ$ system is studied and the effect of the mass polarization is evaluated. The first time the Coulomb interaction for description of the $K (1460)$ resonance is considered. The mass splitting in the $K$ (1460) resonances is evaluated to be in range of 10 MeV with taking into account the Coulomb force. The three-body model with the $K K ˉ$ potential, which has the different strength of the isospin singlet and triplet parts that are related by the condition of obtaining a quasi-bound three-body state is also considered. Our results are in reasonable agreement with the experimental mass of the $K (1460)$ resonance.
nucl-thhep-phPRD(2020)·20 citations
03
Proto-neutron stars with heavy baryons and universal relations
Adriana R. Raduta🇷🇴 · Micaela Oertel🇫🇷 · Armen Sedrakian🇩🇪
We use covariant density functional theory to obtain the equation of state (EoS) of matter in compact stars at non-zero temperature, including the full baryon octet as well as the $Δ (1232)$ resonance states. Global properties of hot $Δ$ -admixed hypernuclear stars are computed for fixed values of entropy per baryon ( $S / A$ ) and lepton fraction ( $Y_{L}$ ). Universal relations between the moment of inertia, quadrupole moment, tidal deformability, and compactness of compact stars are established for fixed values of $S / A$ and $Y_{L}$ that are analogous to those known for cold catalyzed compact stars. We also verify that the $I$ -Love- $Q$ relations hold at finite temperature for constant values of $S / A$ and $Y_{L}$ .
nucl-thastro-ph.HEastro-ph.SRMNRAS(2020)·88 citations
04
Comment on "Breakdown of the tensor component in the Skyrme energy density functional''
H. Sagawa · G. Colò · Ligang Cao
In a recent paper [Phys. Rev. C 101, 014305 (2020)], Dong and Shang claim that the Skyrme original tensor interaction is invalid. Their conclusion is based on the misconception that the Fourier transform of tensor interaction is difficult or even impossible, so that the Skrme-type tensor interaction was introduced in an unreasonable way. We disagree on their claim. In this note, we show that one can easily get the Skyrme force in momentum space by Fourier transformation if one starts from a general central, spin-orbit or tensor interaction with a radial dependence.
nucl-thPRC(2021)·0 citations
05
Chiral three-nucleon force and continuum for dripline nuclei and beyond
Y. Z. Ma · F. R. Xu · L. Coraggio · B. S. Hu · J. G. Li · T. Fukui · L. De Angelis · N. Itaco · A. Gargano
Three-nucleon force and continuum play important roles in reproducing the properties of atomic nuclei around driplines. Therefore it is valuable to build up a theoretical framework where both effects can be taken into account to solve the nuclear Schrödinger equation. To this end, in this letter, we have expressed the chiral three-nucleon force within the continuum Berggren representation, so that bound, resonant and continuum states can be treated on an equal footing in the complex-momentum space. To reduce the model dimension and computational cost, the three-nucleon force is truncated at the normal-ordered two-body level and limited in the $s d$ -shell model space, with the residual three-body term being neglected. We choose neutron-rich oxygen isotopes as the test ground because they have been well studied experimentally, with the neutron dripline determined. The calculations have been carried out within the Gamow shell model. The quality of our results in reproducing the properties of oxygen isotopes around the neutron dripline shows the relevance of the interplay between three-nucleon force and the coupling to continuum states. We also analyze the role played by the chiral three-nucleon force, by dissecting the contributions of the $2 π$ exchange, $1 π$ exchange and contact terms.
nucl-thPLB(2020)·31 citations
06
The complete experiment problem of pseudoscalar meson photoproduction in a truncated partial wave analysis
Yannick Wunderlich🇩🇪
This dissertation treats the problem of complete experiments for pseudoscalar meson photoproduction, in the context of a truncated partial-wave analysis (TPWA). The work contains algebraic and numerical considerations. The influence of measurement uncertainties is examined using bootstrap methods. The thesis was originally published online by the University of Bonn in the 1st quarter of 2019 (links are given in the comments).
nucl-thhep-ph13 citations
07
Nuclear Currents in Chiral Effective Field Theory
Hermann Krebs🇩🇪
In this article, we review the status of the calculation of nuclear currents within chiral effective field theory. After formal discussion of the unitary transformation technique and its application to nuclear currents we will give all available expressions for vector, axial-vector currents. Vector and axial-vector currents will be discussed up to order $Q$ with leading-order contribution starting at order $Q^{- 3}$ . Pseudoscalar and scalar currents will be discussed up to order $Q^{0}$ with leading-order contribution starting at order $Q^{- 4}$ . This is a complete set of expressions in next-to-next-to-next-to-leading-order (N $^{3}$ LO) analysis for nuclear scalar, pseudoscalar, vector and axial-vector current operators. Differences between vector and axial-vector currents calculated via transfer-matrix inversion and unitary transformation techniques are discussed. The importance of consistent regularization is an additional point which is emphasized: lack of consistent regularization of axial-vector current operators is shown to lead to a violation of the chiral symmetry in the chiral limit at order $Q$ . For this reason, a hybrid approach at order $Q$ , discussed in various publications, is non-applicable. To respect the chiral symmetry the same regularization procedure needs to be used in the construction of nuclear forces and current operators. Although full expressions of consistently regularized current operators are not yet available an isoscalar part of the electromagnetic charge operator up to order $Q$ has a very simple form and can be easily regularized in a consistent way. As an application, we review our recent high accuracy calculation of the deuteron charge form factor with a quantified error estimate.
nucl-thhep-phEPJA(2020)·71 citations
08
The Core of $^{25}$ F in the Rotational Model
A.O.Macchiavelli · R.M.Clark · H.L.Crawford · P.Fallon · I.Y.Lee · C.Morse · C.M.Campbell · M.Cromaz · C.Santamaria
In a recent experiment, carried out at RIBF/RIKEN, the $^{25}$ F $(p, 2 p)$ $^{24}$ O reaction was studied at 270 MeV/A in inverse kinematics. Derived spectroscopic factors suggest that the effective core of $^{25}$ F significantly differs from a free $^{24}$ O nucleus. We interpret these results within the Particle-Rotor Model and show that the experimental level scheme of $^{25}$ F can be understood in the rotation-aligned coupling scheme, with its $5/ 2_{1}^{+}$ ground state as the band-head of a decoupled band. The excitation energies of the observed $1/ 2_{1}^{+}$ and $9/ 2_{1}^{+}$ states correlate strongly with the rotational energy of the effective core, seen by the odd proton, and allow us to estimate its $2^{+}$ energy at $\approx$ 3.2 MeV and a moderate quadrupole deformation, $ϵ_{2} \approx 0.15$ . The measured fragmentation of the $π d_{5/2}$ single-particle strength is discussed and some further experiments suggested.
nucl-thnucl-exPRC(2020)·4 citations

Affiliations

first authorsco-authorsvia INSPIRE