Nuclear Theory·nucl-th

Wednesday·September 7, 2022

21 papers—12 primary·9 cross-listed

01
[Submitted on 3 Sept 2022]
Effects of a phase transition on two-pion interferometry in heavy-ion collisions at $s_{NN} = 2.4 - 7.7$ GeV
Pengcheng Li🇩🇪 · Jan Steinheimer🇩🇪 · Tom Reichert🇩🇪 · Apiwit Kittiratpattana🇩🇪 · Marcus Bleicher🇩🇪 · Qingfeng Li🇨🇳
Hanbury-Brown-Twiss (HBT) correlations for charged pions in central Au+Au collisions at $s_{NN} = 2.4 - 7.7 GeV$ (corresponding to beam kinetic energies in the fixed target frame from $E_{lab} = 1.23 to 30 GeV/nucleon$ ) are calculated using the UrQMD model with different equations of state. The effects of a phase transition at high baryon densities are clearly observed in the HBT parameters that are explored. It is found that the available data on the HBT radii, $R_{O} / R_{S}$ and $R_{O}^{2} - R_{S}^{2}$ , in the investigated energy region favors a relatively stiff equation of state at low beam energies which then turns into a soft equation of state at high collision energies consistent with astrophysical constraints on the high density equation of state of QCD. The specific effects of two different phase transition scenarios on the $R_{O} / R_{S}$ and $R_{O}^{2} - R_{S}^{2}$ are investigated. It is found that a phase transition with a significant softening of the equation of state below 4 times nuclear saturation density can be excluded using HBT data. Our results highlight that the pion's $R_{O} / R_{S}$ and $R_{O}^{2} - R_{S}^{2}$ are sensitive to the stiffness of the equation of state, and can be used to constrain and understand the QCD equation of state in the high baryon density region.
Comments:
9 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2209.01413 [pdf]
SCPMA(2023)·45 citations
02
[Submitted on 4 Sept 2022]
Nuclear masses and the equation of state of nuclear matter
Kazuhiro Oyamatsu
The incompressible liquid-drop (ILD) model reproduces masses of stable nuclei rather well. Here we show how the ILD volume, surface, symmetry, and Coulomb energies are related to the equation of state of nuclear matter using the Oyamatsu-Iida (OI) macroscopic nuclear model, which has reasonable many-body energy and isoscalar inhomogeneity gradient energy. We use 304 update interactions, covering wide ranges of the incompressibility $K_{0}$ of symmetric matter and the density slope of symmetry energy $L$ , which fit almost equally empirical mass and radius data of stable nuclei. Thus, the $K_{0}$ and $L$ dependences are nearly frozen in stable nuclei as in the ILD model, leading to clear correlations among interaction and saturation parameters. Furthermore, we assume that the surface energy of the OI model is twice as large as the gradient energy using the size equilibrium conditions of the ILD and OI models. Then, the four energies of the ILD and OI models agree well for stable nuclei with $A ≳ 40$ . Meanwhile, the OI model with $L ≲ 100$ MeV predicts the latest mass data better than those of stable nuclei, and we suggest $20 ≲ L ≲ 90$ MeV, although the lower boundary is not constrained well.
Comments:
Typos in Eqs. (20), (21), and (D2) are corrected
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2209.01571 [pdf]
PTEP(2023)·4 citations
03
[Submitted on 4 Sept 2022]
Has J-PARC E07 observed a $Ξ_{1 s}^{-}$ nuclear state?
E. Friedman🇮🇱 · A. Gal🇮🇱
The Strangeness $S = - 2$ J-PARC E07 emulsion experiment published recently two new $Ξ^{-}$ -- $^{14}$ N capture events, IRRAWADDY and IBUKI, identified by observing weak-decay sequences of pairs of single- $Λ$ hypernuclei and interpreted as $Ξ_{1 s}^{-}$ and $Ξ_{1 p}^{-}$ nuclear bound states, respectively, with binding energies $B_{Ξ^{-}}^{1 s}$ =6.27 $\pm$ 0.27 MeV and $B_{Ξ^{-}}^{1 p}$ =1.27 $\pm$ 0.21 MeV. $Ξ^{-}$ capture events in emulsion play a major role in determining the $Ξ$ -nuclear and the $ΛΛ$ potential strengths. Here we question the assignment of a $Ξ_{1 s}^{-}$ nuclear bound state to IRRAWADDY and offer an alternative assignment as a near-threshold $Ξ_{1 p}^{0}$ -- $^{14}$ C nuclear bound state, slightly admixed with a $Ξ_{1 p}^{-}$ -- $^{14}$ N nuclear bound state component corresponding to IBUKI. We also question using IBUKI's $B_{Ξ^{-}}^{1 p}$ value as is to determine the $Ξ$ -nuclear potential depth. Altogether, $Ξ^{-}$ capture events in $^{12}$ C and $^{16}$ O should prove less ambiguous than in $^{14}$ N.
Comments:
11 pages, 2 figures, 4 tables, v1: as submitted for publication, v2: slightly extended to match PLB published version
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2209.01606 [pdf]
PLB(2023)·16 citations
04
[Submitted on 5 Sept 2022]
Mass splitting and spin alignment for $ϕ$ mesons in a magnetic field in NJL model
Xin-Li Sheng🇨🇳 · Shu-Yun Yang🇨🇳 · Yao-Lin Zou🇨🇳 · Defu Hou🇨🇳
Based on the Nambu-Jona-Lasinio (NJL) model, we develop a framework for calculating the spin alignment of vector mesons and applied it to study $ϕ$ mesons in a magnetic field. We calculate mass spectra for $ϕ$ mesons and observe mass splitting between the longitudinally polarized state and transversely polarized states. The $ϕ$ meson in a thermal equilibrium system is preferred to occupy the state with spin $λ = 0$ than those with spin $λ = \pm 1$ , because the former state has a smaller energy. As a consequence, we conclude that the spin alignment will be larger than 1/3 if one measures along the direction of the magnetic field, which is qualitatively consistent with the recent STAR data. Around the critical temperature $T_{C} = 150$ MeV, the positive deviation from 1/3 is proportional to the square of the magnetic field strength, which agrees with the result from the non-relativistic coalescence model. Including the anomalous magnetic moments for quarks will modify the dynamical masses of quarks and thus affect the mass spectra and spin alignment of $ϕ$ mesons. The discussion of spin alignment in the NJL model may help us better understand the formation of hadron's spin structure during the chiral phase transition.
Comments:
12 pages, 15 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2209.01872 [pdf]
EPJC(2024)·29 citations
05
[Submitted on 5 Sept 2022]
Recovering the conformal limit of color superconducting quark matter within a confining density functional approach
Oleksii Ivanytskyi🇵🇱 · David Blaschke🇵🇱
We generalize a recently proposed confining relativistic density-functional approach to the case of density dependent vector and diquark couplings. The particular behavior of these couplings is motivated by the non-perturbative gluon exchange in dense quark matter and provides the conformal limit at asymptotically high densities. We demonstrate that this feature of the quark matter EoS is consistent with a significant stiffness in the density range typical for the interiors of neutron stars. In order to model these astrophysical objects we construct a family of hybrid quark-hadron EoSs of cold stellar matter. We also confront our approach with the observational constraints on the mass-radius relation of neutron stars and their tidal deformabilities and argue in favor of a quark matter onset at masses below $1.0 M_{⊙}$
Comments:
17 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2209.02050 [pdf]
Particles(2022)·35 citations
06
[Submitted on 5 Sept 2022]
Trimmed Sampling Algorithm for the Noisy Generalized Eigenvalue Problem
Caleb Hicks🇺🇸 · Dean Lee🇺🇸
Solving the generalized eigenvalue problem is a useful method for finding energy eigenstates of large quantum systems. It uses projection onto a set of basis states which are typically not orthogonal. One needs to invert a matrix whose entries are inner products of the basis states, and the process is unfortunately susceptible to even small errors. The problem is especially bad when matrix elements are evaluated using stochastic methods and have significant error bars. In this work, we introduce the trimmed sampling algorithm in order to solve this problem. Using the framework of Bayesian inference, we sample prior probability distributions determined by uncertainty estimates of the various matrix elements and likelihood functions composed of physics-informed constraints. The result is a probability distribution for the eigenvectors and observables which automatically comes with a reliable estimate of the error and performs far better than standard regularization methods. The method should have immediate use for a wide range of applications involving classical and quantum computing calculations of large quantum systems.
Comments:
Final version to appear in Physical Review Research. 6 pages and 3 figures (main), 5 pages and 8 pages (supplemental)
Subjects:
Nuclear Theory (nucl-th); Quantum Gases (cond-mat.quant-gas); High Energy Physics — Lattice (hep-lat); Quantum Physics (quant-ph)
arXiv:
2209.02083 [pdf]
PRResearch(2023)·11 citations
07
[Submitted on 6 Sept 2022]
Simultaneous description of $β$ decay and low-lying structure of neutron-rich even- and odd-mass Rh and Pd nuclei
K. Nomura · L. Lotina · R. Rodríguez-Guzmán · L. M. Robledo
The low-energy structure and $β$ decay properties of neutron-rich even- and odd-mass Pd and Rh nuclei are studied using a mapping framework based on the nuclear density functional theory and the particle-boson coupling scheme. Constrained Hartree-Fock-Bogoliubov calculations using the Gogny-D1M energy density functional are performed to obtain microscopic inputs to determine the interacting-boson Hamiltonian employed to describe the even-even core Pd nuclei. The mean-field calculations also provide single-particle energies for the odd systems, which are used to determine essential ingredients of the particle-boson interactions for the odd-nucleon systems, and of the Gamow-Teller and Fermi transition operators. The potential energy surfaces obtained for even-even Pd isotopes as well as the spectroscopic properties for the even- and odd-mass systems suggest a transition from prolate deformed to $γ$ -unstable and to nearly-spherical shapes. The predicted $β$ decay $lo g f t$ values are shown to be sensitive to the details of the wave functions for the parent and daughter nuclei, and therefore serve as a stringent test of the employed theoretical approach.
Comments:
19 pages, 15 figures, 6 tables
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2209.02232 [pdf]
PRC(2022)·9 citations
08
[Submitted on 6 Sept 2022]
Pion absorption from the lowest atomic orbital in 2H, 3H and 3He
J. Golak🇵🇱 · V. Urbanevych🇵🇱 · R. Skibinski🇵🇱 · H. Witala🇵🇱 · K. Topolnicki🇵🇱 · V. Baru🇩🇪 · A. A. Filin🇩🇪 · E. Epelbaum🇩🇪 · H. Kamada🇯🇵 · A. Nogga🇩🇪
The pi- + 2H -> n + n, pi- + 3H -> n + n + n, pi- + 3He -> n + d and pi- + 3He -> p + n + n capture reactions from the lowest atomic orbitals are studied under full inclusion of final state interactions. Our results are obtained with the single-nucleon and two-nucleon transition operators derived at leading order in chiral effective field theory. The initial and final three-nucleon states are calculated with the chiral nucleon-nucleon SMS potential up to N4LO+ augmented by the consistently regularized chiral N2LO three-nucleon potential. We found that absorption rates depend strongly on the nuclear pion absorption operator used, and its two-body parts change the rates by a few orders of magnitude. The final state interactions between nucleons generated by the two-nucleon forces are also important, while the three-nucleon interaction plays a visible role only in the pi- + 3He -> n + d reaction. Our absorption rate for the pi- + 2H -> n + n process is in good agreement with the experimental data from the hadronic ground-state broadening in pionic deuterium. The capture rates on 3He are also generally consistent with the spectroscopic data within error bars, though our central values are found to be systematically below the data. We show that for the three-body breakup processes the dominant contributions to the absorption rates arise from the quasi-free scattering and final-state interaction kinematical configurations.
Comments:
30 pages, 11 figures; authors' list corrected
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2209.02274 [pdf]
PRC(2022)·2 citations
09
[Submitted on 6 Sept 2022]
"Pseudo-Conformal" Sound Speed in the Core of Compact Stars
Mannque Rho🇫🇷
We present the argument that "pseudo-conformal" symmetry permeates from low density near nuclear matter to high density in the core of massive neutron stars. As a support of this argument, we describe how the quenched $g_{A} \approx 1$ in nuclei and the sound speed $v_{s}^{2} / c^{2} \approx 1/3$ in compact stars are controlled by emerging scale invariance in nuclear interactions. In our description, quasi-baryons could "masquerade" de-confined quarks in the interior of compact stars.
Comments:
Version to be published with a "Note Added"
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2209.02327 [pdf]
Symmetry(2022)·13 citations
10
[Submitted on 27 Aug 2022]
On the influence of Maxwell--Chern--Simons electrodynamics in nuclear fusion involving electronic and muonic molecules
Francisco Caruso · Vitor Oguri · Felipe Silveira · Amos Troper
New results recently obtained (\textit{Annals of Physics} (New York) a.n.~168943) established some non-relativistic ground state solutions for three-body molecules interacting through a Chern--Simons model. Within this model, it was argued that Chern--Simons potential should not help improve the fusion rates by replacing electrons with muons, in the case of particular muonic molecules. This achievement motivated us to investigate quantitatively whether or not the Maxwell--Chern--Simons electrodynamics could influence positively, for example, the probability of having a muon-catalyzed fusion; its contribution to electronic molecules is also considered in this letter. The principal factors related to the probability of elementary nuclear fusion are therefore numerically calculated and compared with their analogs admitting other forms of interaction like $- 1/ ρ$ and $ln (ρ)$ . The analysis carried on here confirms that one should not expect a significant improvement in nuclear fusion rates in the case of muonic molecules, although, surprisingly, the same is not true for electronic molecules, compared with other theoretical predictions. Numerical predictions for the fusion rates for $pp e$ , $pp μ$ , $dd e$ and $dd μ$ molecules are given as well as the predicted value for the tunneling rate for these molecules.
Subjects:
Nuclear Theory (nucl-th); Atomic Physics (physics.atom-ph)
arXiv:
2209.02376 [pdf]
EPL(2022)·0 citations
11
[Submitted on 6 Sept 2022]
Fission dynamics, dissipation and clustering at finite temperature
B. Li · D. Vretenar · Z. X. Ren · T. Nikšić · J. Zhao · P. W. Zhao · J. Meng
The saddle-to-scission dynamics of the induced fission process is explored using a microscopic finite-temperature model based on time-dependent nuclear density functional theory (TDDFT), that allows to follow the evolution of local temperature along fission trajectories. Starting from a temperature that corresponds to the experimental excitation energy of the compound system, the model propagates the nucleons along isentropic paths toward scission. For the four illustrative cases of induced fission of $^{240}$ Pu, $^{234}$ U, $^{244}$ Cm, and $^{250}$ Cf, characteristic fission trajectories are considered, and the partition of the total energy into various kinetic and potential energy contributions at scission is analyzed, with special emphasis on the energy dissipated along the fission path and the prescission kinetic energy. The model is also applied to the dynamics of neck formation and rupture, characterized by the formation of few-nucleon clusters in the low-density region between the nascent fragments.
Comments:
31 pages, 10 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2209.02419 [pdf]
PRC(2023)·20 citations
12
[Submitted on 6 Sept 2022]
Building Surrogate Models of Nuclear Density Functional Theory with Gaussian Processesand Autoencoders
Marc Verriere · Nicolas Schunck · Irene Kim · Petar Marević · Kevin Quinlan · Michelle N. NGo · David Regnier · Raphael David Lasseri
From the lightest Hydrogen isotopes up to the recently synthesized Oganesson (Z=118), it is estimated that as many as about 3000 atomic nuclei could exist in nature. Most of these nuclei are too short-lived to be occurring on Earth, but they play an essential role in astrophysical events such as supernova explosions or neutron star mergers that are presumed to be at the origin of most heavy elements in the Universe. Understanding the structure, reactions, and decays of nuclei across the entire chart of nuclides is an enormous challenge because of the experimental difficulties in measuring properties of interest in such fleeting objects and the theoretical and computational issues of simulating strongly-interacting quantum many-body systems. Nuclear density functional theory (DFT) is a fully microscopic theoretical framework which has the potential of providing such a quantitatively accurate description of nuclear properties for every nucleus in the chart of nuclides. Thanks to high-performance computing facilities, it has already been successfully applied to predict nuclear masses, global patterns of radioactive decay like $β$ or $γ$ decay, and several aspects of the nuclear fission process such as, e.g., spontaneous fission half-lives. Yet, predictive simulations of nuclear spectroscopy or of nuclear fission, or the quantification of theoretical uncertainties and their propagation to applications, would require several orders of magnitude more calculations than currently possible. However, most of this computational effort would be spent into generating a suitable basis of DFT wavefunctions. Such a task could potentially be considerably accelerated by borrowing tools from the field of machine learning and artificial intelligence. In this paper, we review different approaches to applying supervised and unsupervised learning techniques to nuclear DFT.
Comments:
Submitted to Research Topic "Uncertainty Quantification in Nuclear Physics" of Frontiers in Physics
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2209.02467 [pdf]
Front.Phys.(2022)·8 citations

Affiliations

first authorsco-authorsvia INSPIRE