Nuclear Theory·nucl-th

Tuesday·May 11, 2021

19 papers—13 primary·6 cross-listed

01
[Submitted on 7 May 2021]
Application of efficient generator-coordinate subspace-selection algorithm to neutrinoless double- $β$ decay
A.M Romero🇺🇸 · J.M. Yao🇨🇳 · B. Bally🇪🇸 · T.R. Rodríguez🇪🇸 · J. Engel🇺🇸
The generator coordinate method begins with the variational construction of a set of non-orthogonal mean-field states that span a subspace of the full many-body Hilbert space. These states are then often projected onto states with good quantum numbers to restore symmetries, leading to a set with members that can be similar to one another, and it is sometimes possible to reduce this set without greatly affecting results. Here we propose a greedy algorithm that we call the energy-transition-orthogonality procedure (ENTROP) to select subsets of important states. As applied here, the approach selects on the basis of diagonal energy, orthogonality, and contribution to the matrix element that governs neutrinoless double- $β$ decay. We present both shell-model and preliminary ab initio calculations of this matrix element for the decay of $^{76}$ Ge, with quadrupole deformation parameters and the isoscalar pairing strength as generator coordinates. ENTROP converges quickly, reducing significantly the number of basis states needed for an accurate calculation.
Comments:
7 pages, 9 figures, authors added, some details clarified
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2105.03471 [pdf]
PRC(2021)·11 citations
02
[Submitted on 8 May 2021]
Neutron Stars and the Nuclear Equation of State
G. F. Burgio🇮🇹 · I. Vidana🇮🇹 · H.-J. Schulze🇮🇹 · J.-B. Wei (INFN Sezione di Catania)🇮🇹
We review the current status and recent progress of microscopic many-body approaches and phenomenological models, which are employed to construct the equation of state of neutron stars. The equation of state is relevant for the description of their structure and dynamical properties, and it rules also the dynamics of core-collapse supernovae and binary neutron star mergers. We describe neutron star matter assuming that the main degrees of freedom are nucleons and hyperons, disregarding the appearance of quark matter. We compare the theoretical predictions of the different equation-of-state models with the currently available data coming from both terrestrial laboratory experiments and recent astrophysical observations. We also analyse the importance of the nuclear strong interaction and equation of state for the cooling properties of neutron stars. We discuss the main open challenges in the description of the equation of state, mainly focusing on the limits of the different many-body techniques, the so-called "hyperon puzzle," and the dependence of the direct URCA processes on the equation of state.
Comments:
83 pages, 17 figures, 617 references. Accepted for publication in Progress in Particle and Nuclear Physics
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
2105.03747 [pdf]
PPNP(2021)·354 citations
03
[Submitted on 9 May 2021]
Low-rank matrix decompositions for ab initio nuclear structure
A. Tichai🇩🇪 · P. Arthuis🇩🇪 · K. Hebeler🇩🇪 · M. Heinz🇩🇪 · J. Hoppe🇩🇪 · A. Schwenk🇩🇪
The extension of ab initio quantum many-body theory to higher accuracy and larger systems is intrinsically limited by the handling of large data objects in form of wave-function expansions and/or many-body operators. In this work we present matrix factorization techniques as a systematically improvable and robust tool to significantly reduce the computational cost in many-body applications at the price of introducing a moderate decomposition error. We demonstrate the power of this approach for the nuclear two-body systems, for many-body perturbation theory calculations of symmetric nuclear matter, and for non-perturbative in-medium similarity renormalization group simulations of finite nuclei. Establishing low-rank expansions of chiral nuclear interactions offers possibilities to reformulate many-body methods in ways that take advantage of tensor factorization strategies.
Comments:
7 pages, 5 figures, published in Phys. Lett. B
Subjects:
Nuclear Theory (nucl-th); Strongly Correlated Electrons (cond-mat.str-el)
arXiv:
2105.03935 [pdf]
PLB(2021)·15 citations
04
[Submitted on 9 May 2021]
Measuring neutron skin by grazing isobaric collisions
Hao-jie Xu🇨🇳 · Hanlin Li🇨🇳 · Ying Zhou🇨🇳 · Xiaobao Wang🇨🇳 · Jie Zhao🇺🇸 · Lie-Wen Chen🇨🇳 · Fuqiang Wang🇨🇳
Neutron skin thickness ( $Δ r_{np}$ ) of nuclei and the inferred nuclear symmetry energy are of critical importance to nuclear physics and astrophysics. It is traditionally measured by nuclear processes with significant theoretical uncertainties. We recently proposed an indirect measurement of the $Δ r_{np}$ by charged hadron multiplicities in central isobaric collisions at relativistic energies, which are sensitive to nuclear densities. In this Letter, we propose a direct measurement of the $Δ r_{np}$ by using net-charge multiplicities in ultra-peripheral (grazing) collisions of those isobars, under the assumption that they are simple superimposition of nucleon-nucleon interactions. We illustrate this novel approach by the TRENTO and URQMD models.
Comments:
5 pages, 4 figures, version published in PRC
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2105.04052 [pdf]
PRC(2022)·27 citations
05
[Submitted on 10 May 2021]
Relativistic Viscous Hydrodynamics with Angular Momentum
Duan She🇨🇳 · Anping Huang🇺🇸 · Defu Hou🇨🇳 · Jinfeng Liao🇺🇸
Hydrodynamics is a general theoretical framework for describing the long-time large-distance behaviors of various macroscopic physical systems, with its equations based on conservation laws such as energy-momentum conservation and charge conservation. Recently there has been significant interest in understanding the implications of angular momentum conservation for a corresponding hydrodynamic theory. In this work, we examine the key conceptual issues for such a theory in the relativistic regime where the orbital and spin components get entangled. We derive the equations for relativistic viscous hydrodynamics with angular momentum through Navier-Stokes type of gradient expansion analysis and find five new transport coefficients for angular momentum diffusion modes.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Theory (hep-th)
arXiv:
2105.04060 [pdf]
Sci.Bull.(2022)·99 citations
06
[Submitted on 10 May 2021]
Searching for single-particle resonances with the Green's function method
Ya-Tian Wang🇨🇳 · Ting-Ting Sun🇨🇳
Single-particle resonances in the continuum are crucial for studies of exotic nuclei. In this study, the Green's function approach is employed to search for single-particle resonances based on the relativistic-mean-field model. Taking $^{120}$ Sn as an example, we identify single-particle resonances and determine the energies and widths directly by probing the extrema of the Green's functions. In contrast to the results found by exploring for the extremum of the density of states proposed in our recent study [Chin. Phys. C, 44:084105 (2020)], which has proven to be very successful, the same resonances as well as very close energies and widths are obtained. By comparing the Green's functions plotted in different coordinate space sizes, we also found that the results very slightly depend on the space size. These findings demonstrate that the approach by exploring for the extremum of the Green's function is also very reliable and effective for identifying resonant states, regardless of whether they are wide or narrow.
Comments:
8 pages, 4 figures, and 1 table
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2105.04071 [pdf]
Nucl.Sci.Tech.(2021)·10 citations
07
[Submitted on 10 May 2021]
Macroscopic transports in a rotational system with an electromagnetic field
Gaoqing Cao🇨🇳
In this work, we explore macroscopic transport phenomena associated with a rotational system in the presence of an external orthogonal electromagnetic field. Simply based on the lowest Landau level approximation, we derive nontrivial expressions for chiral density and various currents consistently by adopting small angular velocity expansion or Kubo formula. While the generation of anomalous electric current is due to the pseudo gauge field effect of the spin-rotation coupling, the chiral density and current can be simply explained with the help of Lorentz boosts. Finally, Lorentz covariant forms can be obtained by unifying our results and the magnetovorticity effect.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2105.04122 [pdf]
PRD(2021)·5 citations
08
[Submitted on 10 May 2021]
Three- $α$ configurations in the $0^{+}$ states of $^{12} C$
H. Moriya · W. Horiuchi · J. Casal · L. Fortunato
Geometric configurations of three- $α$ particles in the ground- and first-excited $J^{π} = 0^{+}$ states of $^{12}$ C are discussed within two types of $α$ -cluster models which treat the Pauli principle differently. Though there are some quantitative differences especially in the internal region of the wave functions, equilateral triangle configurations are dominant in the ground state, while in the first excited $0^{+}$ state isosceles triangle configurations dominate, originating from $^{8} Be + α$ configurations.
Comments:
7 pages, 4 figures, contribution to the 8th Asia-Pacific Conference on Few-Body Problems in Physics (APFB2020), 1-5 March 2021, Kanazawa, Japan
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2105.04174 [pdf]
Few Body Syst.(2021)·7 citations
09
[Submitted on 10 May 2021]
Collective model with isovector pair and alpha-particle type correlations
R.V. Jolos · E.A. Kolganova · D.A. Sazonov
The collective Hamiltonian including isovector pairing and $α$ -particle type correlation degrees of freedom is constructed. The Hamiltonian is applied to description of the relative energies of the ground states of even-even nuclei around $^{56}$ Ni. A satisfactory description of the experimental data is obtained. A significant improvement of the agreement with the experimental data compared to our previous calculations is explained by inclusion in the Hamiltonian of the dynamical variables describing $α$ -particle type correlations.
Comments:
14 pages, 2 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2105.04234 [pdf]
IJMPE(2021)·1 citation
10
[Submitted on 10 May 2021]
Nonlocal structure of the leading order \textit{ab initio} effective potentials for proton elastic scattering from light nuclei
Ch. Elster · M. Burrows · R.B. Baker · S.P. Weppner · K.D. Launey · P. Maris · G. Popa
Based on the spectator expansion of the multiple scattering series we employ a chiral next-to-next-to-leading order (NNLO) nucleon-nucleon interaction on the same footing in the structure as well as in the reaction calculation to obtain an in leading-order consistent effective potential for nucleon-nucleus elastic scattering, which includes the spin of the struck target nucleon. As an example we present proton scattering off $^{12}$ C.
Comments:
6 pages, 4 figures, Contribution to Proceedings of APFB2020
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2105.04474 [pdf]
Few Body Syst.(2022)·0 citations
11
[Submitted on 10 May 2021]
Halo effective field theory analysis of one-neutron knockout reactions of $^{11} Be$ and $^{15} C$
Chloë Hebborn🇺🇸 · Pierre Capel🇧🇪
Background: One-nucleon knockout reactions provide insightful information on the single-particle structure of nuclei. When applied to one-neutron halo nuclei, they are purely peripheral, suggesting that they could be properly modeled by describing the projectile within a Halo Effective Field Theory (Halo-EFT). Purpose: We reanalyze the one-neutron knockout measurements of $^{11}$ Be and $^{15}$ C-both one-neutron halo nuclei-on beryllium at about 60MeV/nucleon. We consider Halo-EFT descriptions of these nuclei which already provide excellent agreement with breakup and transfer data. Method: We include a Halo-EFT description of the projectile within an eikonal-based model of the reaction and compare its outcome to existing data. Results: Excellent agreement with experiment is found for both nuclei. The asymptotic normalization coefficients inferred from this comparison confirm predictions from \emph{ab initio} nuclear-structure calculations and values deduced from transfer data. Conclusions: Halo-EFT can be reliably used to analyze one-neutron knockout reactions measured for halo nuclei and test predictions from state-of-the-art nuclear structure models on these experimental data.
Comments:
7 pages, 1 figures, 2 tables, Accepted in Phys. Rev. C
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2105.04490 [pdf]
PRC(2021)·21 citations
12
[Submitted on 10 May 2021]
Emergence of rotational modes in nuclear fission
Bency John🇮🇳
Dinuclear systems that occur in the post-saddle to scission stage in nuclear fission process are special transient formations. The diabatic evolution at this stage is studied using the methods of non-equilibrium thermodynamics. A novel explanation for the emergence of intrinsic rotational modes that occur in such a dinucleus is developed by identifying these modes together as an open subsystem that exchanges matter and energy with its environment. The environment consists of all remaining degrees of freedom of the dinucleus, and a weak coupling of the subsystem to this environment facilitates a diabatic energy exchange. Under appropriate non-equilibrium conditions, the available energy is coupled to the work needed for the emergence of self organizing rotational modes. This comes at the expense of increasing microscopic disorder in the form of intrinsic excitations in the prefragments. A simple formalism is presented such that the magnitudes of relevant energy flow through the subsystem are obtained in terms of entropy production rate, entropy expulsion rate and net rate of change of entropy in sub-units of $M e V z s^{- 1} K^{- 1}$ .
Comments:
8 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th); nlin.AO (nlin.AO); Nuclear Experiment (nucl-ex)
arXiv:
2105.04499 [pdf]
0 citations
13
[Submitted on 10 May 2021]
Insights on the peak in the speed of sound of ultradense matter
Maurício Hippert🇺🇸 · Eduardo S. Fraga🇧🇷 · Jorge Noronha🇺🇸
In this work we investigate the minimal physical requirements needed for generating a speed of sound that surpasses its asymptotic conformal limit. It is shown that a peak in the speed of sound of homogeneous matter naturally emerges in the transition from a phase with broken chiral symmetry to one with a gapped Fermi surface. We argue that this could be relevant for understanding the peak in the speed of sound displayed by some of the current models for cold ultradense matter. A minimal model implementation of this mechanism is presented, based on the spontaneous breakdown of an approximate particle-antiparticle symmetry, and its thermodynamic properties are determined.
Comments:
12 pages, 2 figures, matches published version
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2105.04535 [pdf]
PRD(2021)·40 citations

Affiliations

first authorsco-authorsvia INSPIRE