Nuclear Theory·nucl-th

Wednesday·November 1, 2023

8 papers—4 primary·4 cross-listed

01
[Submitted on 31 Oct 2023]
Asymptotic normalization coefficients for $α +^{12} C$ synthesis and the $S$ -factor for $^{12} C (α, γ)^{16} O$ radiative capture
A. M. Mukhamedzhanov · R. J. deBoer · B. F. Irgaziev · L. D. Blokhintsev · A. S. Kadyrov · D. A. Savin
The $^{12} C (α, γ)^{16}$ O reaction, determining the survival of carbon in red giants, is of interest for nuclear reaction theory and nuclear astrophysics. A specific feature of the $^{16}$ O nuclear structure is the presence of two subthreshold bound states, (6.92 MeV, 2 $^{+}$ ) and (7.12 MeV, 1 $^{-}$ ), that dominate the behavior of the low-energy $S$ -factor. The strength of these subthreshold states is determined by their asymptotic normalization coefficients (ANCs), which need to be known with high accuracy. Recently, using a model-independent extrapolation method, Blokhintsev {\it et al.} [Eur. Phys. J. A {\bf 59} (2023) 162] determined the ANCs for the $α$ -particle removal taking into account three subthreshold states in $^{16}$ O. The goal of this paper is to address four main problems elucidating the impact of the subthreshold ANCs on the low-energy $S$ -factor. Firstly, we analyse the connection between variations of the subthreshold ANCs and the low-energy $S$ -factor, in particular, at the most effective energy of $300$ keV. Secondly, we calculate contributions to the $S (300 keV)$ -factor from the subthreshold $1^{-}$ and $2^{+}$ resonances, that are controlled by the subthreshold ANCs. We also evaluate the contribution of the uncertainties of the subthreshold ANCs to the budget of the low-energy $S$ -factor uncertainty, especially, the $S (300 keV)$ -factor. Thirdly, we analyse interference of the subthreshold resonances (SRs) with higher resonances and with the $E 1$ and $E 2$ direct captures to the ground state. Finally, we investigate a correlated effect of the subthreshold and ground-state ANCs on the low-energy $S$ -factor and, in particular, on the $S (300 keV)$ -factor.
Subjects:
Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR)
arXiv:
2310.20255 [pdf]
PRC(2024)·6 citations
02
[Submitted on 31 Oct 2023]
Taweret: a Python package for Bayesian model mixing
Kevin Ingles · Dananjaya Liyanage · Alexandra C. Semposki · John C. Yannotty
Uncertainty quantification using Bayesian methods is a growing area of research. Bayesian model mixing (BMM) is a recent development which combines the predictions from multiple models such that each model's best qualities are preserved in the final result. Practical tools and analysis suites that facilitate such methods are therefore needed. Taweret introduces BMM to existing Bayesian uncertainty quantification efforts. Currently Taweret contains three individual Bayesian model mixing techniques, each pertaining to a different type of problem structure; we encourage the future inclusion of user-developed mixing methods. Taweret's first use case is in nuclear physics, but the package has been structured such that it should be adaptable to any research engaged in model comparison or model mixing.
Comments:
7 pages, 2 figures, submitted to JOSS (Journal of Open Source Software) on 31 October 2023. Comments are welcome!
Subjects:
Nuclear Theory (nucl-th); Data Analysis, Statistics and Probability (physics.data-an); stat.CO (stat.CO)
arXiv:
2310.20549 [pdf]
J.Open Source Softw.(2024)·4 citations
03
[Submitted on 31 Oct 2023]
Multiconfigurational time-dependent density functional theory for atomic nuclei: Technical and numerical aspects
Petar Marević🇫🇷 · David Regnier🇫🇷 · Denis Lacroix🇫🇷
The nuclear time-dependent density functional theory (TDDFT) is a tool of choice for describing various dynamical phenomena in atomic nuclei. In a recent study, we reported an extension of the framework - the multiconfigurational TDDFT (MC-TDDFT) model - that takes into account quantum fluctuations in the collective space by mixing several TDDFT trajectories. In this article, we focus on technical and numerical aspects of the model. We outline the properties of the time-dependent variational principle that is employed to obtain the equation of motion for the mixing function. Furthermore, we discuss evaluation of various ingredients of the equation of motion, including the Hamiltonian kernel, norm kernel, and kernels with explicit time derivatives. We detail the numerical methods for resolving the equation of motion and outline the major assumptions underpinning the model. A technical discussion is supplemented with numerical examples that consider collective quadrupole vibrations in $^{40}$ Ca, particularly focusing on the issues of convergence, treatment of linearly dependent bases, energy conservation, and prescriptions for the density-dependent part of an interaction.
Comments:
23 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex); Quantum Physics (quant-ph)
arXiv:
2310.20557 [pdf]
EPJA(2024)·7 citations
04
[Submitted on 31 Oct 2023]
Reaction Theory
Brady J. Martin · Wayne N. Polyzou
Background: Nuclear reactions are complex, with a large number of possible channels. Understanding how different channels contribute to a given reaction is investigated by perturbing the continuous spectrum. Purpose: To develop tools to investigate reaction mechanisms by identifying the contributions from each reaction channel. Method: Cluster decomposition methods, along with the spectral theory of proper subsystem problems, is used to identify the part of the nuclear Hamiltonian responsible for scattering into each channel. Results: The result is an expression of the nuclear Hamiltonian as a sum over all scattering channels of channel Hamiltonians. Each channel Hamiltonian is constructed from solutions of proper subsystem problems. Retaining any subset of channel Hamiltonians results in a truncated Hamiltonian where the scattering wave functions for the retained channels differ from the wave functions of the full Hamiltonian by $N$ -body correlations. The scattering operator for the truncated Hamiltonian satisfies an optical theorem in the retained channels. Because different channel Hamiltonians do not commute, how they interact determines their contribution to the full dynamics.
Comments:
48 pages, new title, revised introduction and results sections
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2310.20646 [pdf]
1 citation
05
[Submitted on 30 Oct 2023] (cross-list from hep-ph)
Soft modes in hot QCD matter
Jens Braun🇩🇪 · Yong-rui Chen🇨🇳 · Wei-jie Fu🇨🇳 · Fei Gao🇨🇳 · Chuang Huang🇨🇳 · Friederike Ihssen🇩🇪 · Jan M. Pawlowski🇩🇪 · Fabian Rennecke🇩🇪 · Franz R. Sattler🇩🇪 · Yang-yang Tan🇨🇳 · Rui Wen🇨🇳 · Shi Yin🇨🇳
The chiral crossover of QCD at finite temperature and vanishing baryon density turns into a second order phase transition if lighter than physical quark masses are considered. If this transition occurs sufficiently close to the physical point, its universal critical behaviour would largely control the physics of the QCD phase transition. We quantify the size of this region in QCD using functional approaches, both Dyson-Schwinger equations and the functional renormalisation group. The latter allows us to study both critical and non-critical effects on equal footing, facilitating a precise determination of the scaling regime. We find that the physical point is far away from the critical region. Importantly, we show that the physics of the chiral crossover is dominated by soft modes even far beyond the critical region. While scaling functions determine all thermodynamic properties of the system in the critical region, the order parameter potential is the relevant quantity away from it. We compute this potential in QCD using the functional renormalisation group and Dyson-Schwinger equations and provide a simple parametrisation for phenomenological applications.
Comments:
14 pages, 10 figures; v2: version accepted for publication
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2310.19853 [pdf]
PRD(2025)·53 citations
06
[Submitted on 31 Oct 2023] (cross-list from hep-ph)
Evolution of topological charge through chiral anomaly transport
Zilin Yuan🇨🇳 · Anping Huang🇨🇳 · Wen-Hao Zhou🇨🇳 · Guo-Liang Ma🇨🇳 · Mei Huang🇨🇳
Built upon the state-of-the-art model a multiphase transport (AMPT), we develop a new module of chiral anomaly transport (CAT), which can trace the evolution of the initial topological charge of gauge field created through sphaleron transition at finite temperature and external magnetic field in heavy ion collisions. The eventual experimental signals of chiral magnetic effect(CME) can be measured. The CAT explicitly shows the generation and evolution of the charge separation, and the signals of CME through the CAT are quantitatively in agreement with the experimental measurements in Au+Au collision at $s = 200 GeV$ , and the centrality dependence of the CME fraction follows that of the fireball temperature.
Comments:
7 pages, 6 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2310.20194 [pdf]
PRC(2024)·10 citations
07
[Submitted on 31 Oct 2023] (cross-list from hep-ph)
Hybrid Hadronization of Jet Showers from $e^{+} + e^{-}$ to $A + A$ with JETSCAPE
Cameron Parker🇺🇸 · Aaron Angerami🇺🇸 · Ritu Arora🇺🇸 · Steffen Bass🇨🇳 · Shanshan Cao🇺🇸 · Yi Chen🇺🇸 · Raymond Ehlers🇩🇪 · Hannah Elfner🇺🇸 · Wenkai Fan🇺🇸 · Rainer J. Fries🇨🇦 · Charles Gale🇨🇳 · Yayun He🇺🇸 and 39 other authors
In this talk we review jet production in a large variety of collision systems using the JETSCAPE event generator and Hybrid Hadronization. Hybrid Hadronization combines quark recombination, applicable when distances between partons in phase space are small, and string fragmentation appropriate for dilute parton systems. It can therefore smoothly describe the transition from very dilute parton systems like $e^{+} + e^{-}$ to full $A + A$ collisions. We test this picture by using JETSCAPE to generate jets in various systems. Comparison to experimental data in $e^{+} + e^{-}$ and $p + p$ collisions allows for a precise tuning of vacuum baseline parameters in JETSCAPE and Hybrid Hadronization. Proceeding to systems with jets embedded in a medium, we study in-medium hadronization for jet showers. We quantify the effects of an ambient medium, focusing in particular on the dependence on the collective flow and size of the medium. Our results clarify the effects we expect from in-medium hadronization of jets on observables like fragmentation functions, hadron chemistry and jet shape.
Comments:
6 pages, 4 figures, Hard Probes 2023 conference, accepted for publication in Proceedings of Science: version 2, references added, typos fixed
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2310.20631 [pdf]
PoS(2024)·2 citations
08
[Submitted on 31 Oct 2023] (cross-list from hep-ph)
Harmonics of Lepton-Jet Correlations in inclusive and diffractive scatterings
Xuan-Bo Tong🇫🇮 · Bo-Wen Xiao🇨🇳 · Yuan-Yuan Zhang🇨🇳
Based on our previous work, we study the harmonic coefficient of both inclusive and diffractive azimuthal angle dependent lepton-jet correlations in Hadron-Electron Ring Accelerator and the future electron-ion collider. Numerical calculations for inclusive and diffractive harmonics and the ratio of harmonics in $e + Au$ ~and $e + p$ indicate their strong discriminating power for non-saturation model and saturation model. Additionally, we demonstrate that the t-dependent diffractive harmonics can serve as novel observables for nuclear density profile.
Comments:
17 pages, 17 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2310.20662 [pdf]
PRD(2024)·15 citations

Affiliations

first authorsco-authorsvia INSPIRE