Nuclear Theory·nucl-th

Monday·July 31, 2017

9 papers—5 primary·4 cross-listed

01
[Submitted on 27 Jul 2017]
Delta isobars and nuclear saturation
A. Ekström🇸🇪 · G. Hagen🇺🇸 · T. D. Morris🇺🇸 · T. Papenbrock🇺🇸 · P. D. Schwartz🇺🇸
We construct a nuclear interaction in chiral effective field theory with explicit inclusion of the $Δ$ -isobar $Δ (1232)$ degree of freedom at all orders up to next-to-next-to-leading order (NNLO). We use pion-nucleon ( $π N$ ) low-energy constants (LECs) from a Roy-Steiner analysis of $π N$ scattering data, optimize the LECs in the contact potentials up to NNLO to reproduce low-energy nucleon-nucleon scattering phase shifts, and constrain the three-nucleon interaction at NNLO to reproduce the binding energy and point-proton radius of $^{4}$ He. For heavier nuclei we use the coupled-cluster method to compute binding energies, radii, and neutron skins. We find that radii and binding energies are much improved for interactions with explicit inclusion of $Δ (1232)$ , while $Δ$ -less interactions produce nuclei that are not bound with respect to breakup into $α$ particles. The saturation of nuclear matter is significantly improved, and its symmetry energy is consistent with empirical estimates.
Comments:
13 pages, 8 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1707.09028 [pdf]
PRC(2018)·132 citations
02
[Submitted on 28 Jul 2017]
Maris polarization in neutron-rich nuclei
Shubhchintak🇺🇸 · C.A. Bertulani🇺🇸 · T. Aumann🇩🇪
We present a theoretical study of the Maris polarization effect and its application in quasi-free reactions to assess information on the structure of exotic nuclei. We discuss the uncertainties in the calculations of triple differential cross sections and of analyzing powers due the choices of various nucleon-nucleon interactions the optical potentials and limitations of the method. Our calculations explore a large number of choices for the nucleon-nucleon (NN) interactions and the optical potential for nucleon-nucleus scattering. Our study implies that polarization variables in (p,2p) reactions in inverse kinematics can be an effective probe of single-particle structure of nuclei in radioactive-beam facilities.
Comments:
6 pages, 6 figures, amended version following referee suggestions, Phys. Lett. B, to be published
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1707.09149 [pdf]
PLB(2018)·7 citations
03
[Submitted on 28 Jul 2017]
Multicomponent van der Waals equation of state: Applications in nuclear and hadronic physics
Volodymyr Vovchenko🇩🇪 · Anton Motornenko🇩🇪 · Paolo Alba🇩🇪 · Mark I. Gorenstein🇺🇦 · Leonid M. Satarov🇩🇪 · Horst Stoecker🇩🇪
A generalization of the quantum van der Waals equation of state for a multi-component system in the grand canonical ensemble is proposed. The model includes quantum statistical effects and allows to specify the parameters characterizing repulsive and attractive forces for each pair of particle species. The model can be straightforwardly applied to the description of asymmetric nuclear matter and also for mixtures of interacting nucleons and nuclei. Applications of the model to the equation of state of an interacting hadron resonance gas are discussed.
Comments:
20 pages, 5 figures, presentation improved, misprints corrected, version accepted for publication in Physical Review C
Subjects:
Nuclear Theory (nucl-th); Statistical Mechanics (cond-mat.stat-mech); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1707.09215 [pdf]
PRC(2017)·72 citations
04
[Submitted on 28 Jul 2017]
Isospin-Asymmetry Dependence of the Thermodynamic Nuclear Equation of State in Many-Body Perturbation Theory
Corbinian Wellenhofer🇩🇪
The computation of the thermodynamic properties of nuclear matter is a central task of theoretical nuclear physics. The nuclear equation of state is an essential quantity in nuclear astrophysics and governs the properties of neutron stars and core-collapse supernovæ. The framework of chiral effective field theory provides the basis for the description of nuclear interactions in terms of a systematic low-energy expansion. In this thesis, we apply chiral two- and three-nucleon interactions in perturbative many-body calculations of the thermodynamic equation of state of infinite homogeneous nuclear matter. The conceptual issues that arise concerning the consistent generalization of the standard zero-temperature form of many-body perturbation theory to finite temperatures are investigated in detail. The structure of many-body perturbation theory at higher orders is examined, in particular concerning the role of the so-called anomalous contributions. The first-order nuclear liquid-gas phase transition is analyzed with respect to its dependence on temperature and the neutron-to-proton ratio. Furthermore, the convergence behavior of the expansion of the equation of state in terms of the isospin asymmetry is examined. It is shown that the expansion coefficients beyond the quadratic order diverge in the zero-temperature limit, implying a nonanalytic form of the isospin-asymmetry dependence at low temperatures. This behavior is associated with logarithmic terms in the isospin-asymmetry dependence at zero temperature.
Comments:
PhD Thesis, Technical University Munich, Supervisors: Norbert Kaiser, Jeremy W. Holt
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1707.09222 [pdf]
5 citations
05
[Submitted on 28 Jul 2017]
The $α + d \to^{6} Li + γ$ astrophysical $S$ -factor and its implications for Big Bang Nucleosynthesis
A. Grassi · G. Mangano · L.E. Marcucci · O. Pisanti
The $α + d \to^{6} Li + γ$ radiative capture is studied in order to predict the $^{6}$ Li primordial abundance. Within a two-body framework, the $α$ particle and the deuteron are considered the structureless constituents of $^{6}$ Li. Five $α + d$ potentials are used to solve the two-body problem: four of them are taken from the literature, only one having also a tensor component. A fifth model is here constructed in order to reproduce, besides the $^{6}$ Li static properties as binding energy, magnetic dipole and electric quadrupole moments, also the $S$ -state asymptotic normalization coefficient (ANC). The two-body bound and scattering problem is solved with different techniques, in order to minimize the numerical uncertainty of the present results. The long-wavelength approximation is used, and therefore only the electric dipole and quadrupole operators are retained. The astrophysical $S$ -factor is found to be significantly sensitive to the ANC, but in all the cases in good agreement with the available experimental data. The theoretical uncertainty has been estimated of the order of few % when the potentials which reproduce the ANC are considered, but increases up to $≃ 20$ % when all the five potential models are retained. The effect of this $S$ -factor prediction on the $^{6}$ Li primordial abundance is studied, using the public code PArthENoPE. For the five models considered here we find $^{6} Li /$ H $= (0.9 - 1.8) \times 1 0^{- 14}$ , with the baryon density parameter in the 3- $σ$ range of Planck 2015 analysis, $Ω_{b} h^{2} = 0.02226 \pm 0.00023$ .
Comments:
26 pages, 9 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1707.09232 [pdf]
PRC(2017)·21 citations

Affiliations

first authorsco-authorsvia INSPIRE

Delta isobars and nuclear saturation

Maris polarization in neutron-rich nuclei

Multicomponent van der Waals equation of state: Applications in nuclear and hadronic physics

Isospin-Asymmetry Dependence of the Thermodynamic Nuclear Equation of State in Many-Body Perturbation Theory

The α+d→ 6Li+γ astrophysical S-factor and its implications for Big Bang Nucleosynthesis

Affiliations

The $α + d \to^{6} Li + γ$ astrophysical $S$ -factor and its implications for Big Bang Nucleosynthesis