Nuclear Theory·nucl-th

Tuesday·December 24, 2019

20 papers—10 primary·10 cross-listed

01
[Submitted on 20 Dec 2019]
Neutron elastic scattering on calcium isotopes from chiral nuclear optical potentials
T.R. Whitehead · Y. Lim · J.W. Holt
We formulate microscopic neutron-nucleus optical potentials from many-body perturbation theory based on chiral two- and three-body forces. The neutron self energy is first calculated in homogeneous matter to second order in perturbation theory, which gives the central real and imaginary terms of the optical potential. The real spin-orbit term is calculated separately from the density matrix expansion using the same chiral interaction as in the self energy. Finally, the full neutron-nucleus optical potential is derived within the improved local density approximation utilizing mean field models consistent with the chiral nuclear force employed. We compare the results of the microscopic calculations to phenomenological models and experimental data up to projectile energies of $E = 200$ MeV. Experimental elastic differential scattering cross sections and vector analyzing powers are generally well reproduced by the chiral optical potential, but we find that total cross sections are overestimated at high energies.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1912.10043 [pdf]
PRC(2020)·20 citations
02
[Submitted on 21 Dec 2019]
Rapidity dependence of global polarization in heavy ion collisions
Zuo-Tang Liang🇨🇳 · Jun Song🇨🇳 · Isaac Upsal🇨🇳 · Qun Wang🇨🇳 · Zhang-Bu Xu🇨🇳
We use a geometric model for the hadron polarization with an emphasis on the rapidity dependence. It is based on the model of Brodsky, Gunion, and Kuhn and that of the Bjorken scaling. We make predictions for the rapidity dependence of the hadron polarization in the collision energy range 7.7-200 GeV by taking a few assumed forms of the parameters. The predictions can be tested by future experiments.
Comments:
RevTex 4, 16 pages, 11 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1912.10223 [pdf]
CPC(2021)·27 citations
03
[Submitted on 21 Dec 2019]
High-momentum components in the $^{4}$ He nucleus caused by inter-nucleon correlations
Mengjiao Lyu · Takayuki Myo · Hiroshi Toki · Hisashi Horiuchi · Chang Xu · Niu Wan
High-momentum components of nuclei are essential for understanding the underlying inter-nucleon correlations in nuclei. We perform the comprehensive analysis for the origin of the high-momentum components of $^{4}$ He in the framework of Tensor-optimized High-momentum Antisymmetrized Molecular Dynamics (TO-HMAMD), which is a completely variational approach as an $ab$ $ini t i o$ theory starting from the bare nucleon-nucleon ( $N N$ ) interaction. The analytical derivations are provided for the nucleon momentum distribution of the Antisymmetrized Momentum Dynamics (AMD) wave functions, with subtraction of center-of-mass motion. The nucleon momentum distribution for $^{4}$ He is calculated by applying a new expansion technique to our $ab$ $ini t i o$ wave function, and agrees with the values extracted from experimental data up to the high-momentum region. Fine-grained analysis is performed for the high-momentum components in $^{4}$ He with respect to different nucleon correlations. Contributions from tensor, central with short-range, and many-body correlations are extracted from the nucleon momentum distributions. The manifestation of tensor correlation around 2 fm $^{- 1}$ region is explicitly confirmed by comparing the momentum distributions predicted using different types of $N N$ interactions with and without the tensor force.
Comments:
7 pages, 6 figures, under review in Phys. Lett. B
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1912.10288 [pdf]
PLB(2020)·24 citations
04
[Submitted on 22 Dec 2019]
Beyond mean-field boson-fermion description of odd nuclei
Kosuke Nomura
We develop a novel theoretical method for calculating spectroscopic properties of those nuclei with odd number of nucleons, that is based on the nuclear density functional theory and the particle-boson coupling scheme. Self-consistent mean-field calculation based on the DFT is performed to provide microscopic inputs to build the Hamiltonian of the interacting boson-fermion systems, which gives excitation spectra and transition rates of odd-mass nuclei. The method is successfully applied to identify the quantum shape phase transitions and the role of octupole correlations in odd-mass nuclei, and is extended further to odd-odd nuclear systems.
Comments:
8 pages, 6 figures; Proceedings XXVI Nuclear Physics Workshop, Kazimierz Dolny, Poland, 24-29 September 2019
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1912.10392 [pdf]
Acta Phys.Polon.Supp.(2020)·0 citations
05
[Submitted on 22 Dec 2019]
A Survey of Nuclear Pasta in the Intermediate Density Regime: Structure Functions for Neutrino Scattering
B. Schuetrumpf🇩🇪 · G. Martínez-Pinedo🇩🇪 · P.-G. Reinhard🇩🇪
Background: Nuclear pasta matter, emerging due to the competition between the long-range Coulomb force and the short-range strong force, is believed to be present in astrophysical scenarios, such as neutron stars and core-collapse supernovae. Its structure can have a high impact e.g. on neutrino transport or the tidal deformability of neutron stars. Purpose: We investigate the impact of nuclear pasta on neutrino interactions and compare the results to uniform matter. Method: We calculate the elastic and inelastic static structure factors for nuclear pasta matter using density functional theory (DFT), which contain the main nuclear input for neutrino scattering. Results: Each pasta structure leaves a unique imprint in the elastic structure factor and it is largely enhanced. The inelastic structure factors are very similar for all configurations. Conclusion: Nuclear pasta has a noticeable impact on neutrino neutral-current scattering opacities. While for inelastic reactions the cross section is reduced, the elastic coherent scattering increases dramatically. The effect can be of importance for the cooling of neutron stars as well as for core-collapse supernova models.
Comments:
10 pages, 10 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
1912.10510 [pdf]
PRC(2020)·18 citations
06
[Submitted on 22 Dec 2019]
Corrections to the Bethe formula for average ionization energy loss of relativistic charged particles in solids. I. Mott's corrections
O. Voskresenskaya🇷🇺
Based on the proposed representation of the Mott corrections to the Bethe stopping formula in the form of rapidly convergent series of quantities bilinear in the Mott partial amplitudes, the numerical calculations were performed for these corrections over a wide range of nuclear charge number of the incident particles at various values of their relative velocity.
Comments:
PDFLaTeX, 7 pages; v2: some typos corrected
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1912.10547 [pdf]
0 citations
07
[Submitted on 22 Dec 2019]
Dissipative type theories for Bjorken and Gubser flows
Esteban Calzetta🇦🇷 · Lucas Cantarutti🇦🇷
We use the dissipative type theory (DTT) framework to solve for the evolution of conformal fluids in Bjorken and Gubser flows from isotropic initial conditions. The results compare well with both exact and other hydrodynamic solutions in the literature. At the same time, DTTs enforce the Second Law of thermodynamics as an exact property of the formalism, at any order in deviations from equilibrium, and are easily generalizable to more complex situations.
Comments:
40 pages, 13 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1912.10562 [pdf]
Int.J.Mod.Phys.A(2020)·20 citations
08
[Submitted on 23 Dec 2019]
Electron- versus neutrino-nucleus scattering
J.E. Amaro🇪🇸 · M.B. Barbaro🇮🇹 · J.A. Caballero🇪🇸 · R. González-Jiménez🇪🇸 · G.D. Megias🇯🇵 · I. Ruiz Simo🇪🇸
We illustrate the connection between electron and neutrino scattering off nuclei and show how the former process can be used to constrain the description of the latter. After reviewing some of the nuclear models commonly used to study lepton-nucleus reactions, we describe in detail the SuSAv2 model and show how its predictions compare with the available electron- and neutrino-scattering data over the kinematical range going from the quasi-elastic peak to pion-production and highly inelastic scattering.
Comments:
Shortened version, 71 pages, review article, 52 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1912.10612 [pdf]
J.Phys.G(2020)·70 citations
09
[Submitted on 23 Dec 2019]
Lepton kinematics in low energy neutrino-Argon interactions
Nils Van Dessel🇧🇪 · Alexis Nikolakopoulos🇧🇪 · Natalie Jachowicz🇧🇪
Background: Neutrinos in the low-energy regime provide a gateway to a wealth of interesting physics. While plenty of literature exists on detailing the calculation and measurement of total reaction strengths, relatively little attention is paid to the measurement and modeling of the final lepton through differential cross sections at low energies, despite the experimental importance. Purpose: We calculate differential cross sections for low-energy neutrino-nucleus scattering. We examine the role played by forbidden transitions in these distributions and how this differs across different energies and nuclear target masses. Attention is also paid to predictions for typical experimental neutrino spectra. Method: The differential cross sections are calculated within a Continuum Random Phase Approximation framework, which allows us to include collective excitations induced by long-range correlations. The Coulomb interaction of the final lepton in charged current events is treated in an effective way. Results: Kinematic distributions are calculated for $^{16}$ O, $^{40}$ Ar and $^{208}$ Pb. $^{40}$ Ar model results are compared for CC ( $ν_{e}, e^{-}$ ) reactions to events generated by the MARLEY event generator, with noticeable discrepancies. Conclusion: Forbidden transitions have a marked effect on the kinematic distributions of the final lepton at low-energy kinematics, such as for DAR neutrinos or for a Fermi-Dirac spectrum at low temperature. This could introduce biases in experimental analyses. Backwards scattering is noticeably more prominent than with MARLEY.
Comments:
11 pages, 17 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1912.10714 [pdf]
PRC(2020)·19 citations
10
[Submitted on 23 Dec 2019]
Excitation of monopole pairing vibrations in two-neutron transfer reaction: a semiclassical approach
V.I. Abrosimov · A.I. Levon
For studying the collective pairing excitations of nuclei, the two-nucleon transfer reactions in superfluid nuclei (the pairing gap of the ground state is not zero), in particular, the (p,t) reaction, are of the greatest interest. A simple model of monopole pairing excitations in superfluid nuclei on the basis of the semiclassical time-dependent Hartree-Fock-Bogolyubov theory in the limit of small amplitudes is considered. Using the anomalous density response function, the monopole pairing mode in the energy region of double pairing gap and the variation of the pairing gap associated with this mode are found. The ratio of the spectroscopic factor for the excitation of monopole pairing vibrations in the (p,t) reaction in even superfluid nuclei to the spectroscopic factor for the transfer of two neutrons to the ground state of the daughter nucleus (the relative spectroscopic factor) is estimated. For this, it is assumed that the relative spectroscopic factor is proportional to the pairing gap variation associated with the monopole pairing vibrations in agreement with the corresponding quantum expression. Numerical estimate of the relative spectroscopic factors for superfluid nuclei of the rare-earth and actinide regions shows that the spectroscopic factor for the two-neutron transfer, leading to the excitation of the monopole pairing vibrations, does not exceed several percent of the spectroscopic factor for the transfer of two neutrons to the ground state. This semiclassical estimate is in agreement with the experimental rations of the cross sections for the excitation of 0+states in the energy region of double pairing gap to the cross sections for the excitation of the ground states for superfluid nuclei of the rare-earth and actinide regions.
Comments:
10 pages, 2 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1912.10963 [pdf]
0 citations

Affiliations

first authorsco-authorsvia INSPIRE