Nuclear Theory·nucl-th

Tuesday·February 5, 2019

19 papers—9 primary·10 cross-listed

01
Impact of the nuclear mass uncertainties on the r process
Z. Y. Wang · Q. G. Wen · T. H. Heng
Based on a simple site-independent approach, we attempt to reproduce the solar $r$ -process abundance with four nuclear mass models, and investigate the impact of the nuclear mass uncertainties on the $r$ process. In this paper, we first analyze the reliability of an adopted empirical formula for $β$ -decay half-lives which is a key ingredient for the $r$ process. Then we apply four different mass tables to study the $r$ -process nucleosynthesis together with the calculated $β$ -decay half-lives, and the existing $β$ -decay data from FRDM+QRPA is also considered for comparison. The numerical results show that the main features of the solar $r$ -process pattern and the locations of the abundance peaks can be reproduced well via the $r$ -process simulations. Moreover, we also find that the mass uncertainties can significantly affect the derived astrophysical conditions for the $r$ -process site, and resulting in a remarkable impact on the $r$ process.
nucl-thIJMPE(2019)·0 citations
02
Effects of strong magnetic fields on neutron $^{3} P_{2}$ superfluidity with spin-orbit interactions
Shigehiro Yasui🇯🇵 · Chandrasekhar Chatterjee🇯🇵 · Muneto Nitta🇯🇵
We discuss neutron $^{3} P_{2}$ phases in the core of neutron stars in strong magnetic field (magnetars). The neutron $^{3} P_{2}$ pairing provides a wide variety of condensates, such as the uniaxial nematic and (D $_{2}$ and D $_{4}$ ) biaxial nematic, with different symmetries stemming from the combinations of spin and momentum. Based on the spin-orbital angular momentum coupling and the spin-magnetic field coupling of the neutrons, we derive the Ginzburg-Landau equation containing higher order terms of the magnetic field. We investigate the phase diagram of the neutron $^{3} P_{2}$ superfluidity, and find that the D $_{2}$ biaxial nematic phase is extended by the higher order terms of the magnetic field. We also discuss the thermodynamic properties, the heat capacity and the spin susceptibility.
nucl-thastro-ph.HEcond-mat.supr-conhep-phJPS Conf.Proc.(2019)·11 citations
03
Nuclear electric dipole moment as a good probe of CP violation
Nodoka Yamanaka🇫🇷
The electric dipole moment (EDM) is an excellent probe of new physics beyond the standard model of particle physics. The EDM of light nuclei is particularly interesting due to the high sensitivity to the hadron level CP violation. In this proceedings contribution, we investigate the mechanism of the generation of the EDM for several light nuclei and the prospect for the discovery of new physics.
nucl-thhep-exhep-phnucl-exJPS Conf.Proc.(2019)·0 citations
04
Jost function based on the Hartree-Fock-Bogoliubov formalism
K. Mizuyama · N. Nhu Le · T. Dieu Thuy · T. V. Nhan Hao
We formulate the Jost function formalism based on the Hartree-Fock-Bogoliubov (HFB) theory which has been used to represent the nature of the superfluidity of nucleus. The Jost function based on the HFB can give the analytic representation of the S-matrix for the nucleon elastic scattering targeting on the open-shell nucleus taking into account the pairing effect. By adopting the Woods-Saxon potential, we show the numerical results of S-matrix poles and their trajectories with varying the pairing strength in two cases of Fermi energies. The total cross sections in each cases for neutron elastic scattering are also analyzed, and we confirmed some staggering shapes or sharp resonances originated from the effect of pairing can be seen in the cross section.
nucl-thPRC(2019)·12 citations
05
Three- and four-body kaonic nuclear states: Binding energies and widths
Sajjad Marri🇮🇷 · Jafar Esmaili🇮🇷
Using separable potentials for $K ˉ N - π Σ$ interaction, we investigated four-body kaonic nuclear systems such as $K^{-} pp n$ and $K^{-} K^{-} pp$ , with the Faddeev AGS method in the momentum representation. The Faddeev calculations are based on the quasi-particle method and the method of the energy dependent pole expansion was used to obtain the separable representation for the integral kernels in the three- and four-body equations. Different types of $K ˉ N - π Σ$ potentials based on phenomenological and chiral SU(3) approach are used and it was shown that the kaonic nuclear systems under consideration are tightly bound.
nucl-thEPJA(2019)·18 citations
06
GW170817 constraints on the properties of a neutron star in the presence of WIMP dark matter
Abdul Quddus🇮🇳 · Grigorios Panotopoulos🇵🇹 · Bharat Kumar🇮🇳 · Shakeb Ahmad🇮🇳 · S. K. Patra🇮🇳
The properties of a neutron star are studied in the presence of dark matter. We have considered a relatively light Weakly Interacting Massive Particle (WIMP) as a dark matter candidate with properties suggested by the results of the DAMA/LIBRA collaboration, realized for instance within the framework of the Next-to-Minimal Supersymmetric Standard Model. The dark matter particle interacts with the baryonic matter of a neutron star through Higgs bosons. The dark matter variables are essentially fixed using the results of the DAMA/LIBRA experiment, which are then used to build the Lagrangian density for the WIMP-nucleon interaction inside a neutron star. We have used the effective field theory motivated relativistic mean field model to study the equations-of-state in the presence of dark matter. The predicted equations-of-state are used in the Tolman-Oppenheimer-Volkoff equations to obtain the mass-radius relations, the moment of inertia, and effects of the tidal field on a neutron star. The calculated properties are compared with the corresponding data of the GW170817 event.
nucl-thJ.Phys.G(2020)·62 citations
07
Bayesian optimization in ab initio nuclear physics
A. Ekström🇸🇪 · C. Forssén🇸🇪 · C. Dimitrakakis🇸🇪 · D. Dubhashi🇸🇪 · H. T. Johansson🇸🇪 · A. S. Muhammad🇸🇪 · H. Salomonsson🇸🇪 · A. Schliep🇸🇪
Theoretical models of the strong nuclear interaction contain unknown coupling constants (parameters) that must be determined using a pool of calibration data. In cases where the models are complex, leading to time consuming calculations, it is particularly challenging to systematically search the corresponding parameter domain for the best fit to the data. In this paper, we explore the prospect of applying Bayesian optimization to constrain the coupling constants in chiral effective field theory descriptions of the nuclear interaction. We find that Bayesian optimization performs rather well with low-dimensional parameter domains and foresee that it can be particularly useful for optimization of a smaller set of coupling constants. A specific example could be the determination of leading three-nucleon forces using data from finite nuclei or three-nucleon scattering experiments.
nucl-thcs.LGstat.MLJ.Phys.G(2019)·23 citations
08
Nuclear collective dynamics in the lattice Hamiltonian Vlasov method
Rui Wang🇨🇳 · Lie-Wen Chen🇨🇳 · Zhen Zhang🇨🇳
The lattice Hamiltonian method is developed for solving the Vlasov equation with nuclear mean-field based on the Skyrme pseudopotential up to next-to-next-to-next-to leading order. The ground states of nuclei are obtained through varying the total energy with respect to the density distribution of nucleons. Owing to the self-consistent treatment of initial nuclear ground state and the exact energy conservation in the lattice Hamiltonian method, the present framework of solving the Vlasov equation exhibits very stable nuclear ground state evolution. As a first application of the new lattice Hamiltonian Vlasov method, we explore the iso-scalar giant monopole and iso-vector giant dipole modes of finite nuclei. The obtained results are shown to be comparable to that from random-phase approximation and consistent with the experimental data, indicating the capability of the present method in dealing with the long-time near-equilibrium nuclear dynamics.
nucl-thastro-ph.SRnucl-exPRC(2019)·24 citations
09
Galilean invariance restoration on the lattice
Ning Li🇺🇸 · Serdar Elhatisari🇩🇪 · Evgeny Epelbaum🇩🇪 · Dean Lee🇺🇸 · Bing-Nan Lu🇺🇸 · Ulf-G. Meißner🇩🇪
We consider the breaking of Galilean invariance due to different lattice cutoff effects in moving frames and a nonlocal smearing parameter which is used in the construction of the nuclear lattice interaction. The dispersion relation and neutron-proton scattering phase shifts are used to investigate the Galilean invariance breaking effects and ways to restore it. For $S$ -wave channels, $^{1} S_{0}$ and $^{3} S_{1}$ , we present the neutron-proton scattering phase shifts in moving frames calculated using both Lüscher's formula and the spherical wall method, as well as the dispersion relation. For the $P$ and $D$ waves, we present the neutron-proton scattering phase shifts in moving frames calculated using the spherical wall method. We find that the Galilean invariance breaking effects stemming from the lattice artifacts partially cancel those caused by the nonlocal smearing parameter. Due to this cancellation, the Galilean invariance breaking effect is small, and the Galilean invariance can be restored by introducing Galilean invariance restoration operators.
nucl-thhep-latPRC(2019)·19 citations

Affiliations

first authorsco-authorsvia INSPIRE