Nuclear Theory·nucl-th

Thursday·December 14, 2023

13 papers—8 primary·5 cross-listed

01
Quantum Computing for Nuclear Physics
Martin J. Savage🇺🇸
Future quantum computers are anticipated to be able to perform simulations of quantum many-body systems and quantum field theories that lie beyond the capabilities of classical computation. This will lead to new insights and predictions for systems ranging from dense non-equilibrium matter, to low-energy nuclear structure and reactions, to high-energy collisions. I present an overview of digital quantum simulations in nuclear physics, with select examples relevant for studies of quark matter.
nucl-thhep-latnucl-exEPJ Web Conf.(2024)·17 citations
02
Theoretical developments on the initial state in relativistic particle collisions
Heikki Mäntysaari🇫🇮
We discuss recent progress towards developing accurate initial state descriptions for heavy ion collisions focusing on weak coupling based approaches, that enable one to constrain the high-energy structure of nuclei from deep inelastic scattering or proton-nucleus collisions. We review recent developments to determine the event-by-event fluctuating nuclear geometry, to describe gluon saturation phenomena at next-to-leading order accuracy, and to include longitudinal dynamics to the initial state descriptions.
nucl-thhep-phEPJ Web Conf.(2024)·2 citations
03
{\alpha}-decay half-lives for even-even isotopes of W to U
Yong-Beom Choi · Chang-Hwan Lee · Myeong-Hwan Mun · Soonchul Choi · Youngman Kim
We investigate {\alpha}-decay half-lives for 74 {\le} Z {\le} 92 even-even nuclei within the semiclassical WKB approximation in deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc). The {\alpha}-particle preformation factors are estimated from cluster-formation model using both empirical AME2020 binding energies and numerical ones obtained by a deep neural network (DNN) study in which available DRHBc binding energies are used as training set. We find that our estimated {\alpha}-decay half-lives are qualitatively in agree with experimental results. We also compare our results with the empirical formulae, ZZCW and UNIV. Based on these observation, we extend our predictions of {\alpha}-decay half-lives for the isotopes whose experimental data are not available.
nucl-thPRC(2024)·12 citations
04
Shell-Model Description of the Isospin-Symmetry-Breaking Correction to Gamow-Teller $β$ -Decay Rates and Their Mirror Asymmetries
Latsamy Xayavong · Yeunhwan Lim
The isospin-symmetry breaking correction, denoted as $δ_{C}$ , is introduced for the first time within the shell-model framework to the nuclear matrix element of Gamow-Teller transitions. $δ_{C}$ is separated into two components: the isospin mixing term, $δ_{C 1}$ , induced by the Coulomb and nuclear charge-dependent forces in the effective Hamiltonian, and the radial mismatch term, $δ_{C 2}$ , arising from differences between proton and neutron realistic wave functions. Consequently, the refinement strategy developed for superallowed $0^{+} \to 0^{+}$ Fermi transitions is applied to Gamow-Teller transitions as well. It is demonstrated that, to a given precision level, the shell model calculation of $δ_{C}$ converges much faster than the calculation of the transition matrix element. Furthermore, higher-order correction terms are investigated and considered for consistent study of our works. Various interesting properties of the leading correction terms are discovered within the two-level model and parentage expansion of the one-body transition densities in angular momentum and isospin spaces. One such property is the dependence of $δ_{C 1}$ on the isospin admixture amplitude, $α$ , starting from the first order, while the same model yields $δ_{C 1} = α^{2}$ for Fermi transitions. The calculated $δ_{C}$ values are then utilized to evaluate the mirror asymmetry of Gamow-Teller transition strengths, which are compared with available experimental data and other theoretical calculations. Due to the refined fitting procedure of the Woods-Saxon potential parameters and the improved convergence as a function of intermediate state number, our results show better agreement on average compared to those of Smirnova and Volpe [Nucl. Phys. {\bf A 714}, 441 (2003)].
nucl-thnucl-exPRC(2025)·7 citations
05
Neutrinos from pre-supernova in the framework of TQRPA method
A. A. Dzhioev · A. V. Yudin · N. V. Dunina-Barkovskaya · A. I. Vdovin
We propose a new method for calculating spectra and luminosities for (anti)neutrinos produced in the pre-supernova environment by weak processes with hot nuclei. It is based on the thermal quasiparticle random phase approximation (TQRPA), that allows microscopic thermodynamically consistent calculations of the weak-interaction response of nuclei at finite temperatures. For realistic representative pre-supernova conditions from the stellar evolution code MESA, we compute (anti)neutrino luminosities and spectra arising from neutral- and charged-current weak reactions with hot $^{56}$ Fe and compare them with the contribution of thermal processes. We find that the TQRPA approach produces not only a higher total luminosity of electron neutrinos (mainly born in the electron capture reaction), compared to the standard technique based on the large-scale shell model (LSSM) weak-interaction rates, but also a harder neutrino spectrum. Besides, applying the TQRPA and LSSM, we find that in the context of electron antineutrino generation, the neutral-current nuclear de-excitation (ND) process via neutrino-antineutrino pair emission is at least as important as the electron-positron pair annihilation process. We also show that flavor oscillations enhance the high-energy contribution of the ND process to the electron antineutrino flux. This could potentially be important for pre-supernova antineutrino registration by the Earth's detectors.
nucl-thastro-ph.HEMNRAS(2023)·7 citations
06
Non-hydrodynamic response in QCD-like plasma
Weiyao Ke🇨🇳 · Yi Yin🇨🇳
Quark-gluon plasma's (QGP) properties at non-hydrodynamic and non-perturbative regimes remain largely unexplored. Here, we examine the response functions describing how a QGP-like plasma responds to initial energy-momentum disturbance in both static and Bjorken-expanding plasma at non-hydrodynamic gradient using the Boltzmann equation in the relaxation-time approximation (RTA). We show that the resulting response functions are remarkably similar in both static and expanding backgrounds at non-hydrodynamic gradients. While non-hydrodynamic response can not be described by the conventional first-order and second-order theories, its behavior is reasonably captured by the extended version of hydrodynamics proposed by us (arXiv: 2208.01046). The potential sensitivity of the Euclidean correlator to non-hydrodynamic response is also illustrated.
nucl-thhep-phhep-thJHEP(2024)·4 citations
07
How to explain ENDF-6 to computers: A formal ENDF format description language
Georg Schnabel · Daniel Lopez Aldama · Roberto Capote
The ENDF-6 format, widely used worldwide for storing and disseminating nuclear data, is managed by the Cross Sections Evaluation Working Group (CSEWG) and fully documented in the ENDF-6 formats manual. This manual employs a combination of formal and natural language, introducing the possibility of ambiguity in certain parts of the format specification. To eliminate the possibility of ambiguity, this contribution proposes a generalization of the formal language used in the ENDF-6 formats manual, which is precisely defined in extended Backus-Naur form (EBNF). This formalization also offers several other advantages, notably reducing the complexity of creating and updating parsing and validation programs for ENDF-6 formatted files. Moreover, the availability of a formal description enables the automatic mapping of the low-level ENDF-6 representation, provided by a sequence of numbers, to a more human-friendly hierarchical representation with variable names. Demonstrating these advantages, almost the entire ENDF-6 format description has been translated into the proposed formal language, accompanied by a reference implementation of a parser/translator. This implementation leverages the formal format specification to enable reading, writing, and validating ENDF-6 formatted files.
nucl-th0 citations
08
$^{12}$ C and $α$ -clusters, $0^{+}$ spectrum, and Hoyle-state candidates in $^{24}$ Mg
J. Cseh · G. Riczu · D. G. Jenkins
Background: A recent inelastic alpha-scattering experiment [Phys. Rev. Lett. 129, 102701 (2022)] found $0^{+}$ resonances in $^{24}$ Mg on and above the $^{12}$ C+ $^{12}$ C break-up threshold. It has been conjectured that the states have a $^{12}$ C+ $^{12}$ C cluster structure, and play a similar role in accelerating $^{12}$ C+ $^{12}$ C fusion to the manner in which the Hoyle state accelerates production of $^{12}$ C in massive stars. Purpose: We wish to build up a quantitative theoretical basis for the considerations of the Hoyle-state paradigm, by calculating the distribution of the $0^{+}$ states in the shell, as well as in the relevant cluster models. Methods: We determine the spectrum of excited $0^{+}$ states in $^{24}$ Mg nucleus using multiconfigurational dynamical symmetry calculations leading to a unified description of the quartet (or shell), $^{12}$ C+ $^{12}$ C and $^{20}$ Ne+ $^{4}$ He cluster configurations. Results: The density of $0^{+}$ states in the quartet spectrum is comparable to that found in experiment; however, the density of cluster states is considerably less. Conclusions: The recently observed alpha-scattering resonances do not seem to be simple $^{12}$ C+ $^{12}$ C cluster states, but are more plausibly interpreted as fragmented cluster states due to coupling to quartet excitations, as background states.
nucl-th2 citations

Affiliations

first authorsco-authorsvia INSPIRE