Nuclear Theory·nucl-th

Monday·June 24, 2024

11 papers—7 primary·4 cross-listed

01
[Submitted on 20 Jun 2024]
New $^{63}$ Ga(p, $γ$ ) $^{64}$ Ge and $^{64}$ Ge(p, $γ$ ) $^{65}$ As reaction rates corresponding to the temperature regime of thermonuclear X-ray bursts
Ning Lu · Yi Hua Lam · Alexander Heger · Zi Xin Liu · Hidetoshi Yamaguchi
We compute the $^{63}$ Ga(p, $γ$ ) $^{64}$ Ge and $^{64}$ Ge(p, $γ$ ) $^{65}$ As thermonuclear reaction rates using the latest experimental input supplemented with theoretical nuclear spectroscopic information. The experimental input consists of the latest proton thresholds of $^{64}$ Ge and $^{65}$ As, and the nuclear spectroscopic information of $^{65}$ As, whereas the theoretical nuclear spectroscopic information for $^{64}$ Ge and $^{65}$ As are deduced from the full pf-shell space configuration-interaction shell-model calculations with the GXPF1A Hamiltonian. Both thermonuclear reaction rates are determined with known uncertainties at the energies that correspond to the Gamow windows of the temperature regime relevant to Type I X-ray bursts, covering the typical temperature range of the thermonuclear runaway of the GS 1826 $-$ 24 periodic bursts and SAX J1808.4 $-$ 3658 photospheric radius expansion bursts.
Comments:
Accepted by Physical Review C on 7 Nov 2024 with minor correction, finalized version, 40 pages, 7 main figures (colorblind-friendly colors), 8 tables, data availability: https://doi.org/10.5281/zenodo.13901500
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Experiment (nucl-ex)
arXiv:
2406.14624 [pdf]
PRC(2024)·4 citations
02
[Submitted on 20 Jun 2024]
Symplectic symmetry approach to clustering in atomic nuclei: The case of $^{24}$ Mg
H. G. Ganev
Symplectic symmetry approach to clustering (SSAC) in atomic nuclei, recently proposed, is modified and further developed in more detail. It is firstly applied to the light two-cluster $^{20}$ Ne + $α$ system of $^{24}$ Mg, the latter exhibiting well developed low-energy $K^{π} = 0_{1}^{+}$ , $K^{π} = 2_{1}^{+}$ and $K^{π} = 0_{1}^{-}$ rotational bands in its spectrum. A simple algebraic Hamiltonian, consisting of dynamical symmetry, residual and vertical mixing parts is used to describe these three lowest rotational bands of positive and negative parity in $^{24}$ Mg. A good description of the excitation energies is obtain by considering only the $S U (3)$ cluster states restricted to the stretched many-particle Hilbert subspace, built on the leading Pauli allowed $S U (3)$ multiplet for the positive- and negative-parity states, respectively. The coupling to the higher cluster-model configurations allows to describe the known low-lying experimentally observed $B (E 2)$ transition probabilities within and between the cluster states of the three bands under consideration without the use of an effective charge.
Comments:
13 pages, 4 figures, 2 tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2406.14730 [pdf]
Commun.Theor.Phys.(2025)·2 citations
03
[Submitted on 21 Jun 2024]
$^{3}$ He spin-dependent structure functions within the relativistic Light-Front Hamiltonian dynamics
Eleonora Proietti🇮🇹 · Filippo Fornetti🇮🇹 · Emanuele Pace🇮🇹 · Matteo Rinaldi🇮🇹 · Giovanni Salmè🇮🇹 · Sergio Scopetta🇮🇹
$^{3}$ He spin-dependent structure functions, $g_{1}^{3} (x)$ and $g_{2}^{3} (x)$ , which parametrize the hadronic tensor in polarized deep-inelastic scattering, were evaluated within the Poincaré covariant light-front framework. The Bakamjian-Thomas construction of the Poincaré generators allows us to make use of a realistic $^{3}$ He wave function, obtained from refined nuclear phenomenological potentials. The same approach was already successfully applied to the $^{3}$ He and $^{4}$ He unpolarized deep-inelastic scattering. To investigate the neutron polarized structure functions, $g_{1}^{n}$ and $g_{2}^{n}$ , a readily implementable procedure, aimed at extracting the neutron spin structure functions from those of $^{3}$ He, is shown to hold. Moreover, the first moment of $g_{1}^{3} (x)$ was evaluated, aiming at providing a valuable check of the Bjorken sum rule. The present analysis is relevant for experiments nvolving polarized beams planned at the future facilities, like the Electron Ion Colliders.
Comments:
13 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2406.15010 [pdf]
PRC(2024)·1 citation
04
[Submitted on 21 Jun 2024]
Evidence for Three- $α$ Breathing Modes Uncovered by Control Neural Network
Zheng Cheng · Mengjiao Lyu · Takayuki Myo · Hisashi Horiuchi · Hiroshi Toki · Zhongzhou Ren · Masahiro Isaka · Mengyun Mao · Hiroki Takemoto · Niu Wan · Wenlong You · Qing Zhao
This work introduces a new Control Neural Network (Ctrl.NN) method to uncover evidence of exotic quantum state, \textit{i.e.}, the breathing modes in 3- $α$ resonant states of $^{12}$ C nucleus. We provide the most precise microscopic description to date for the $^{12}$ C energy spectrum, identify two new exotic breathing states, and uncover strong evidence that directly connects the recent experimental observations to the breathing modes. The Ctrl.NN method significantly simplifies numerical calculations of quantum systems under multiple constraints and offers a new perspective for solving the nuclear many-body problem.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2406.15060 [pdf]
PLB(2025)·9 citations
05
[Submitted on 21 Jun 2024]
Electromagnetic isovector form factors of the transition from the $N^{*} (1520)$ to the nucleon
Di An🇸🇪 · Stefan Leupold🇸🇪
Dispersion theory is used to provide a model-independent low-energy representation of the three electromagnetic isovector transition form factors $N^{*} (1520) \to N$ . At low energies the virtual photon couples dominantly to a pion pair. Taking the very well understood pion vector form factor and pion re-scattering into consideration, the determination of the transition form factors is traced back to the determination of pion-baryon scattering amplitudes. Their low-energy aspects are parametrized by baryon exchange, accounting for the main decay channels of the $N^{*} (1520)$ . Short-distance physics is encoded in subtraction constants that are fitted to data on space-like form factors and hadronic decays. It is shown that a limitation in the determination of the subtraction constants lies in the fact that isovector form factors require sufficient information about the differences between protons and neutrons. In particular, this calls for improvements in the form factor extraction from the electroproduction of the $N^{*} (1520)$ on the neutron. Via the dispersion relations, space- and time-like regions are naturally connected from first principles. This allows to predict the time-like form factors that enter the Dalitz decays $N^{*} (1520) \to N e^{-} e^{+}$ and $N^{*} (1520) \to N μ^{-} μ^{+}$ . Under the assumption of the dominance of the isovector over the isoscalar channel, the Dalitz decay distributions are predicted.
Comments:
The paper will be submitted to PRD. Figures updated
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2406.15115 [pdf]
6 citations
06
[Submitted on 21 Jun 2024]
Universality of scaled particle spectra in ultrarelativistic heavy-ion collisions
Cicero D. Muncinelli🇧🇷 · Fernando G. Gardim🇧🇷 · David D. Chinellato🇦🇹 · Gabriel S. Denicol🇧🇷 · Andre V. Giannini🇧🇷 · Matthew Luzum🇧🇷 · Jorge Noronha🇺🇸 · Tiago Nunes da Silva🇧🇷 · Jun Takahashi🇧🇷 · Giorgio Torrieri🇧🇷
We study the transverse momentum spectra of identified particles in ultrarelativistic collisions of large and small collision systems. In order to isolate information contained in the momentum dependence, we propose to scale the spectra by the total particle number and mean transverse momentum -- global quantities which are already well studied. We observe an interesting, nearly universal, centrality-independent shape in the scaled spectra, similar to scalings that have been studied previously. This scaling behavior breaks down at large transverse momentum and for very small systems, such as those produced in p-p collisions. We perform hybrid hydrodynamic simulations and show that, in these simulations, a centrality-independent shape is a consequence of an event-by-event independence. Our results motivate further theoretical and experimental investigations of the regime of validity of this scaling phenomenon and their physical interpretation at different collision energies and systems.
Comments:
V2: 7 pages, 3 figures. PRC approved version
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2406.15208 [pdf]
PRC(2025)·7 citations
07
[Submitted on 21 Jun 2024]
Hybrid Star Properties with NJL and MFTQCD Model: A Bayesian Approach
Milena Albino🇵🇹 · Tuhin Malik🇵🇹 · Márcio Ferreira🇵🇹 · Constança Providência🇵🇹
The composition of the core of neutron stars (NS) is still under debate. One possibility is that because of the high densities reached in their cores, matter could be deconfined into quark matter. We investigate the existence of hybrid stars, using microscopic models to describe different phases of matter. Within the adopted microscopic models we calculate properties of NS and properties of matter. We want to probe the pQCD calculations influence and analyze properties that identify a transition to deconfined matter. Bayesian approach is applied to generate 8 sets of equations of state (EOS). A Maxwell construction is adopted to describe the deconfinement transition. For the hadron phase, we consider a stiff and a soft EOS obtained from the Relativistic Mean Field model with nonlinear meson terms. For the quark phase, we use 2 different models: the Nambu-Jona-Lasinio model with multiquark interactions and the Mean Field Theory of QCD, a model similar to the vector MIT bag model. Bayesian inference was applied to determine the model parameters that satisfy the X-ray observations from NICER and have phase transition at densities between 0.15 - 0.40 fm $^{- 3}$ . We also applied restrictions from the pQCD calculations to half of the sets. Hybrid stars are compatible with current observational data. The pQCD restrictions reduce the value of the $M_{ma x}$ . However, even applying this restriction, the models were able to reach values of $2.1 - 2.3 M_{⊙}$ . The conformal limit was still not attained at the center of the most massive stars. The vector interactions are essential to describe hybrid stars with a mass above $2 M_{⊙}$ . The multiquark interactions introduced may affect the limits of some quantities considered as indicators of the presence of a deconfined phase. It is possible to find a set of EOS, that predict that inside NS the renormalized matter trace anomaly is always positive.
Comments:
There are 17 pages, 12 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2406.15337 [pdf]
PRD(2024)·29 citations

Affiliations

first authorsco-authorsvia INSPIRE

New 63Ga(p,γ)64Ge and 64Ge(p,γ)65As reaction rates corresponding to the temperature regime of thermonuclear X-ray bursts

Symplectic symmetry approach to clustering in atomic nuclei: The case of 24Mg

3He spin-dependent structure functions within the relativistic Light-Front Hamiltonian dynamics

Evidence for Three-α Breathing Modes Uncovered by Control Neural Network

Electromagnetic isovector form factors of the transition from the N∗(1520) to the nucleon

Universality of scaled particle spectra in ultrarelativistic heavy-ion collisions

Hybrid Star Properties with NJL and MFTQCD Model: A Bayesian Approach

Affiliations

New $^{63}$ Ga(p, $γ$ ) $^{64}$ Ge and $^{64}$ Ge(p, $γ$ ) $^{65}$ As reaction rates corresponding to the temperature regime of thermonuclear X-ray bursts

Symplectic symmetry approach to clustering in atomic nuclei: The case of $^{24}$ Mg

$^{3}$ He spin-dependent structure functions within the relativistic Light-Front Hamiltonian dynamics

Evidence for Three- $α$ Breathing Modes Uncovered by Control Neural Network

Electromagnetic isovector form factors of the transition from the $N^{*} (1520)$ to the nucleon