Nuclear Theory·nucl-th

Tuesday·October 1, 2019

19 papers—11 primary·8 cross-listed

01
[Submitted on 26 Sept 2019]
Insights into the Origin of Mass
Craig D. Roberts🇨🇳
Atomic nuclei are the core of everything we can see. At the first level of approximation, their atomic weights are simply the sum of the masses of all the nucleons they contain. Each nucleon has a mass $m_{N} \approx 1$ GeV, i.e. approximately 2000-times the electron mass. The Higgs boson produces the latter, but what produces the nucleon mass? This is the crux: the vast bulk of the mass of a nucleon is lodged with the energy needed to hold quarks together inside it; and that is supposed to be explained by quantum chromodynamics (QCD), the strong-interaction piece within the Standard Model. This contribution canvasses the potential for a coherent effort in QCD phenomenology and theory, coupled with experiments at existing and planned facilities, to reveal the origin and distribution of mass by focusing on the properties of the strong-interaction Nambu-Goldstone modes. Key experiments are approved at JLab 12; planned with COMPASS++/AMBER at CERN; and could deliver far-reaching insights by exploiting the unique capabilities foreseen at an electron ion collider.
Comments:
9 pages, 4 figures. Summary of a plenary presentation at "INPC 2019 - 27th International Nuclear Physics Conference", Glasgow, UK, 29 July to 2 August, 2019. arXiv admin note: substantial text overlap with arXiv:1909.11102
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1909.12832 [pdf]
J.Phys.Conf.Ser.(2020)·11 citations
02
[Submitted on 27 Sept 2019]
Regularized pseudopotential for mean-field calculations
K. Bennaceur🇫🇷 · J. Dobaczewski🇬🇧 · T. Haverinen🇫🇮 · M. Kortelainen🇫🇮
We present preliminary results obtained with a finite-range two-body pseudopotential complemented with zero-range spin-orbit and density-dependent terms. After discussing the penalty function used to adjust parameters, we discuss predictions for binding energies of spherical nuclei calculated at the mean-field level, and we compare them with those obtained using the standard Gogny D1S finite-range effective interaction.
Comments:
6 pages, 2 figures, contribution to the conference proceedings for INPC 2019 (Glasgow)
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1909.12879 [pdf]
J.Phys.Conf.Ser.(2020)·1 citation
03
[Submitted on 28 Sept 2019]
Finite-range separable pairing interaction in Cartesian coordinates
A.M. Romero · J. Dobaczewski · A. Pastore
Within a simple SO(8) algebraic model, the coexistence between isoscalar and isovector pairing modes can be successfully described using a mean-field method plus restoration of broken symmetries. In order to port this methodology to real nuclei, we need to employ realistic density functionals in the pairing channel. In this article, we present an analytical derivation of matrix elements of a separable pairing interaction in Cartesian coordinates and we correct errors of derivations available in the literature. After implementing this interaction in the code hfodd, we study evolution of pairing gaps in the chain of deformed Erbium isotopes, and we compare the results with a standard density-dependent contact pairing interaction.
Comments:
Contribution to the proceedings of the 27th International Nuclear Physics Conference (INPC), 29th July - 2nd August (2019), Glasgow, United Kingdom
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1909.13041 [pdf]
J.Phys.Conf.Ser.(2020)·2 citations
04
[Submitted on 30 Sept 2019]
Robust ab initio predictions for nuclear rotational structure in the Be isotopes
M. A. Caprio · P. J. Fasano · J. P. Vary · P. Maris · J. Hartley
No-core configuration interaction (NCCI) calculations for p-shell nuclei give rise to rotational bands, identified by strong intraband E2 transitions and by rotational patterns for excitation energies, electromagnetic moments, and electromagnetic transitions. However, convergence rates differ significantly for different rotational observables and for different rotational bands. The choice of internucleon interaction may also substantially impact the convergence rates. Consequently, there is a substantial gap between simply observing the qualitative emergence of rotation in ab initio calculations and actually carrying out detailed quantitative comparisons. In this contribution, we illustrate the convergence properties of rotational band energy parameters extracted from NCCI calculations, and compare these predictions with experiment, for the isotopes 7-11Be, and for the JISP16 and Daejeon16 interactions.
Comments:
14 pages, 6 figures; presented at the International Conference on Nuclear Theory in the Supercomputing Era, Daejeon, Republic of Korea, November 2018
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1909.13417 [pdf]
Proceedings of the International Conferen…·2 citations
05
[Submitted on 30 Sept 2019]
To reach neutron-rich heavy and superheavy nuclei by multinucleon transfer reactions with radioactive isotopes
Peng-Hui Chen🇨🇳 · Fei Niu🇨🇳 · Wei Zuo🇨🇳 · Zhao-Qing Feng🇨🇳
The dynamical mechanism of multinucleon transfer (MNT) reactions has been investigated within the dinuclear system (DNS) model, in which the sequential nucleon transfer is described by solving a set of microscopically derived master equations. Production cross sections, total kinetic energy spectra, angular distribution of formed fragments in the reactions of $^{124, 132}$ Sn+ $^{238}$ U/ $^{248}$ Cm near Coulomb barrier energies are thoroughly analyzed. It is found that the total kinetic energies of primary fragments are dissipated from the relative motion energy and rotational energy of the two colliding nuclei. The fragments are formed in the forward angle domain. The energy dependence of the angular spectra is different between projectile-like and target-like fragments. Isospin equilibrium is governed under the potential energy surface. The production cross sections of neutron-rich isotopes are enhanced around the shell closure.
Comments:
10 pages, 8 figures, 1 table
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1909.13431 [pdf]
PRC(2020)·22 citations
06
[Submitted on 30 Sept 2019]
Effects of curvature of the symmetry energy in Sn+Sn reactions at 270 MeV/nucleon
Ya-Fei Guo · Gao-Chan Yong
Based on the Isospin-dependent Boltzmann-Uehling-Uhlenbeck (IBUU) transport model, the isotope Sn+Sn reactions at 270 MeV/nucleon are investigated. It is shown that nucleon and meson observables in the Sn+Sn reactions at 270 MeV/nucleon cannot effectively probe the high-density symmetry energy. These observables, however, are sensitive to the curvature of the symmetry energy. It thus sheds light on the study of the high-density behavior of the nuclear symmetry energy by extracting the curvature of the symmetry energy through the interpretation of forthcoming RIBF/RIKEN related data.
Comments:
5 pages, 8 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1909.13566 [pdf]
2 citations
07
[Submitted on 30 Sept 2019]
Transition densities and form factors in the triangular $α$ -cluster model of $^{12}$ C with application to $^{12}$ C+ $α$ scattering
A. Vitturi · J. Casal · L. Fortunato · E.G. Lanza
Densities and transition densities are computed in an equilateral triangular alpha-cluster model for $^{12}$ C, in which each $α$ particle is taken as a gaussian density distribution. The ground-state, the symmetric vibration (Hoyle state) and the asymmetric bend vibration are analyzed in a molecular approach and dissected into their components in a series of harmonic functions, revealing their intrinsic structures. The transition densities in the laboratory frame are then used to construct form-factors and to compute DWBA inelastic cross-sections for the $^{12}$ C $(α, α^{'})$ reaction. The comparison with experimental data indicates that the simple geometrical model with rotations and vibrations gives a reliable description of reactions where $α$ -cluster degrees of freedom are involved.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1909.13571 [pdf]
PRC(2020)·13 citations
08
[Submitted on 27 Sept 2019]
Combining nuclear reactions and structure with the dispersive optical model
W. H. Dickhoff · M. C. Atkinson
A review of recent applications of the nonlocal dispersive optical model (DOM) is presented that allows a simultaneous description of nuclear structure and nuclear reactions. An assessment of the quality of the resulting potentials for $^{40}$ Ca and $^{48}$ Ca is discussed for the description of the $(e, e^{'} p)$ reaction to valence hole states and the possibility of interpreting the data in terms of absolute spectroscopic factors. The relevance of these results in the context of conflicting interpretations between transfer and knockout reactions is pointed out as well as the importance of proton reaction cross sections for isotopes with neutron excess. Application of the nonlocal DOM to $^{48}$ Ca incorporates the effect of the 8 additional neutrons and allows for an excellent description of elastic scattering data of both protons and neutrons. The corresponding neutron distribution constrained by all available data generates a prediction for the neutron skin that is larger than most mean-field and available \textit{ab initio} results. Results are presented for the most recent nonlocal DOM analysis of $^{208}$ Pb.
Comments:
7 pages, 3 figures, INPC2019 invited talk. arXiv admin note: substantial text overlap with arXiv:1812.07622
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1909.13750 [pdf]
J.Phys.Conf.Ser.(2020)·1 citation
09
[Submitted on 30 Sept 2019]
Comment on the recent article "Fission dynamics of from saddle to scission and beyond" by Bulgac et al., published in Phys. Rev. {\bf C 100}, 034615 (2019)
Sakir Ayik🇺🇸 · Denis Lacroix🇫🇷
In this note we provide answers to criticisms made the appendix D of the article [Phys. Rev. C100, 034615 (2019)] against to the theory developed recently and known a "Stochastic Mean-Field" (SMF) approach and its applications. Briefly, we list our replies and leave the judgment to the readers.
Comments:
3 pages, no figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1909.13761 [pdf]
1 citation
10
[Submitted on 30 Sept 2019]
Long-range azimuthal correlations for partially coherent pion emission in proton-proton collisions
Peng Ru🇨🇳 · Wei-Ning Zhang🇨🇳
In this paper, we investigate the influence of coherent pion emission on long-range azimuthal correlations in relativistic proton-proton collisions. We study the pion momentum distribution for a coherent source with both transverse and Bjorken longitudinal expansions, and calculate the two-particle correlation function $C (Δ η, Δ ϕ)$ . A "ridge" structure is observed in the correlation function $C (Δ η, Δ ϕ)$ of the coherent pion emission, whether the coherent source is expanding or static. The onset of this long-range azimuthal correlation can be traced back to the asymmetric initial transverse profile of the coherent source, owing to the interference in coherent emission. We further construct a partially coherent pion-emitting source by incorporating a chaotic emission component. From the experimental data of the two-pion Hanbury-Brown-Twiss correlations in pp collisions at $s = 7$ TeV, we extract a coherent fraction of pion emission, which increases with increasing charged-particle multiplicity, as an input of the partially coherent source model. The ridge structure is observed in the correlation function $C (Δ η, Δ ϕ)$ for the partially coherent source. The correlation becomes stronger at higher multiplicities because of the larger degrees of coherence. The results in this work are meaningful for fully understanding the collectivity in the small system of pp collisions.
Comments:
9 pages, 8 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1909.13785 [pdf]
PLB(2020)·1 citation
11
[Submitted on 30 Sept 2019]
Form factors for the Nucleon-to-Roper electromagnetic transition at large- $Q^{2}$
José Rodríguez-Quintero🇪🇸 · Daniele Binosi🇮🇹 · Chen Chen🇩🇪 · Ya Lu🇨🇳 · Craig D. Roberts🇨🇳 · Jorge Segovia🇪🇸
We report on a recent calculation of all Roper-related electromagnetic transtions form factors, covering the range of energies that next-to-come planned experiments are expected to map. Direct reliable calculations were performed, within a Poincaré covariant approach of the three-body bound-state problem, up to $Q^{2} / m_{N}^{2}$ =6; approximated then by applying the Schlessinger point method and the results eventually extended up to $Q^{2} / m_{N}^{2} ≃$ 12 via analytic continuation.
Comments:
NStar 2019 proceedings
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1909.13793 [pdf]
EPJ Web Conf.(2020)·8 citations

Affiliations

first authorsco-authorsvia INSPIRE