Nuclear Theory·nucl-th

Monday·May 29, 2023

8 papers—3 primary·5 cross-listed

01
[Submitted on 26 May 2023]
Machine learning transforms the inference of the nuclear equation of state
Yongjia Wang · Qingfeng Li
Our knowledge of the properties of dense nuclear matter is usually obtained indirectly via nuclear experiments, astrophysical observations, and nuclear theory calculations. Advancing our understanding of the nuclear equation of state (EOS, which is one of the most important properties and of central interest in nuclear physics) has relied on various data produced from experiments and calculations. We review how machine learning is revolutionizing the way we extract EOS from these data, and summarize the challenges and opportunities that come with the use of machine learning.
Comments:
4 pages, 1 figure, To appear in Frontiers of Physics
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2305.16686 [pdf]
Front.Phys.(Beijing)(2023)·21 citations
02
[Submitted on 26 May 2023]
The Fate of excited state of $^{4} He$
Mario Gattobigio🇫🇷 · Alejandro Kievsky🇮🇹
We investigate the properties of the excited state of $^{4} He$ , $^{4} He^{*}$ , within the framework of Efimov physics and its connection to the unitary point of the nuclear interaction. We explore two different approaches to track the trajectory of $^{4} He^{*}$ as it crosses the $^{3} H$ +p threshold and potentially becomes a resonant state. The first approach involves an analytical continuation of the energy with respect to the Coulomb coupling, while the second approach introduces an artificial four-body force that it is gradually released. By utilizing Padé approximants and extrapolation techniques, we estimate the energy and width of the resonance. Our results suggest a central energy value of $E_{R} = 0.060 (3)$ MeV and a width of $Γ/2 = 0.036 (6)$ MeV using the Coulomb analysis, and $E_{R} = 0.068 (1)$ MeV and $Γ/2 = 0.007 (5)$ MeV with the four-body force analysis. Interestingly, these results are consistent with calculations based on {\it ab-initio} nuclear interactions but differ from the accepted values of the $0^{+}$ resonance energy and width. This highlights the challenges in accurately determining the properties of resonant states in light nuclei and calls for further investigations and refinements in theoretical approaches.
Subjects:
Nuclear Theory (nucl-th); physics.atm-clus (physics.atm-clus)
arXiv:
2305.16814 [pdf]
Few Body Syst.(2023)·8 citations
03
[Submitted on 26 May 2023]
Impact of initial fluctuations and nuclear deformations in isobar collisions
Jian-fei Wang🇨🇳 · Hao-jie Xu🇨🇳 · Fuqiang Wang🇨🇳
Relativistic isobar ( $_{44}^{96}$ Ru+ $_{44}^{96}$ Ru and $_{40}^{96}$ Zr+ $_{40}^{96}$ Zr) collisions have revealed intricate differences in their nuclear size and shape, inspiring unconventional studies of nuclear structure using relativistic heavy ion collisions. In this study, we investigate the relative differences in the mean multiplicity ( $R_{⟨ N_{ch} ⟩}$ ) and the second- ( $R_{ϵ_{2}}$ ) and third-order eccentricity ( $R_{ϵ_{3}}$ ) between isobar collisions using initial state models. It is found that initial fluctuations and nuclear deformations have negligible effects on $R_{⟨ N_{ch} ⟩}$ in most central collisions, while both are important for the $R_{ϵ_{2}}$ and $R_{ϵ_{3}}$ , the degree of which is sensitive to the underlying nucleonic or sub-nucleonic degree of freedom. These features, compared to real data, may probe the particle production mechanism and the physics underlying nuclear structure.
Comments:
7 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2305.17114 [pdf]
Nucl.Sci.Tech.(2024)·17 citations
04
[Submitted on 25 May 2023] (cross-list from hep-ph)
Power Counting to Saturation
Iain Stewart🇺🇸 · Varun Vaidya🇺🇸
We present a description of saturation in small $x$ deep inelastic scattering from power counting in a top-down effective theory derived from QCD. A factorization formula isolates the universal physics of the nucleus at leading power in $x$ . The onset of saturation is then understood as a breakdown in the expansion in an emergent power counting parameter, which is defined by the matrix element of a gauge invariant operator. We identify a new radiation mode, which enables us to extend previous literature by distinguishing the appearance of the saturation scale from the transition to non-linear evolution.
Comments:
5 pages, 2 figures, Version to appear in PRD letters
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2305.16393 [pdf]
PRD(2024)·11 citations
05
[Submitted on 25 May 2023] (cross-list from hep-ph)
Model independent analysis of femtoscopic correlation functions: An application to the $D_{s 0}^{*} (2317)$
Natsumi Ikeno🇯🇵 · Genaro Toledo🇲🇽 · Eulogio Oset🇪🇸
We face the inverse problem of obtaining the interaction between coupled channels from the correlation functions of these channels. We apply the method to the interaction of the $D^{0} K^{+}$ , $D^{+} K^{0}$ , and $D_{s}^{+} η$ channels, from where the $D_{s 0}^{*} (2317)$ state emerges. We use synthetic data extracted from an interaction model based on the local hidden gauge approach and find that the inverse problem can determine the existence of a bound state of the system with a precision of about 20 MeV. At the same time, we can determine the isospin nature of the bound state and its compositeness in terms of the channels. Furthermore, we evaluate the scattering length and effective range of all three channels, as well as the couplings of the bound state found to all the components. Lastly, the size parameter of the source function, $R$ , which in principle should be a magnitude provided by the experimental teams, can be obtained from a fit to the data with relatively high accuracy. These findings show the value of the correlation function to learn about the meson-meson interaction for systems which are difficult to access in other present facilities.
Comments:
8 pages, 2 figures, 2 tables: numerical results are updated and table II is added
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2305.16431 [pdf]
PLB(2023)·63 citations
06
[Submitted on 25 May 2023] (cross-list from nucl-ex)
Simultaneous $γ$ -ray and electron spectroscopy of $^{182, 184, 186}$ Hg isotopes
M. Stryjczyk🇧🇪 · B. Andel🇧🇪 · J. G. Cubiss🇨🇭 · K. Rezynkina🇧🇪 · T. R. Rodríguez🇪🇸 · J. E. García-Ramos🇪🇸 · A. N. Andreyev🇬🇧 · J. Pakarinen🇫🇮 · P. Van Duppen🇧🇪 · S. Antalic🇸🇰 · T. Berry🇬🇧 · M. J. G. Borge🇪🇸 and 39 other authors
Background: The mercury isotopes around $N = 104$ are a well-known example of nuclei exhibiting shape coexistence. Mixing of configurations can be studied by measuring the monopole strength $ρ^{2} (E 0)$ , however, currently the experimental information is scarce and lacks precision, especially for the $I^{π} \to I^{π}$ ( $I \neq = 0$ ) transitions. Purpose: The goals of this study were to increase the precision of the known branching ratios and internal conversion coefficients, to increase the amount of available information regarding excited states in $^{182, 184, 186}$ Hg and to interpret the results in the framework of shape coexistence using different models. Method: The low-energy structures in $^{182, 184, 186}$ Hg were populated in the $β$ decay of $^{182, 184, 186}$ Tl, produced at ISOLDE and purified by laser ionization and mass separation. The $γ$ -ray and internal conversion electron events were detected by five germanium clover detectors and a segmented silicon detector, respectively, and correlated in time to build decay schemes. Results: In total, 193, 178 and 156 transitions, including 144, 140 and 108 observed for the first time in a $β$ -decay experiment, were assigned to $^{182, 184, 186}$ Hg, respectively. Internal conversion coefficients were determined for 23 transitions, out of which 12 had an $E 0$ component. Extracted branching ratios allowed the sign of the interference term in $^{182}$ Hg as well as $ρ^{2} (E 0; 0_{2}^{+} \to 0_{1}^{+})$ and $B (E 2; 0_{2}^{+} \to 2_{1}^{+})$ in $^{184}$ Hg to be determined. By means of electron-electron coincidences, the $0_{3}^{+}$ state was identified in $^{184}$ Hg. The experimental results were qualitatively reproduced by five theoretical approaches, the IBM with configuration mixing with two different parametrizations, the General Bohr Hamiltonian, the BMF model and the SCCM model. However, a quantitative description is lacking.
Comments:
21 pages, 30 figures, accepted for publication in Physical Review C
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2305.16442 [pdf]
PRC(2023)·0 citations
07
[Submitted on 26 May 2023] (cross-list from physics.chem-ph)
Connections and performances of Green's function methods for charged and neutral excitations
Enzo Monino · Pierre-François Loos
In recent years, Green's function methods have garnered considerable interest due to their ability to target both charged and neutral excitations. Among them, the well-established $G W$ approximation provides accurate ionization potentials and electron affinities and can be extended to neutral excitations using the Bethe-Salpeter equation (BSE) formalism. Here, we investigate the connections between various Green's function methods and evaluate their performance for charged and neutral excitations. Comparisons with other widely-known second-order wave function methods are also reported. Additionally, we calculate the singlet-triplet gap of cycl[3,3,3]azine, a model molecular emitter for thermally activated delayed fluorescence, which has the particularity of having an inverted gap thanks to a substantial contribution from the double excitations. We demonstrate that, within the $G W$ approximation, a second-order BSE kernel with dynamical correction is required to predict this distinctive characteristic.
Comments:
18 pages, 1 figure
Subjects:
physics.chem-ph (physics.chem-ph); cond-mat.mtrl-sci (cond-mat.mtrl-sci); Strongly Correlated Electrons (cond-mat.str-el); Nuclear Theory (nucl-th); Computational Physics (physics.comp-ph)
arXiv:
2305.16959 [pdf]
J.Chem.Phys.(2023)·11 citations
08
[Submitted on 26 May 2023] (cross-list from hep-ph)
Cabibbo suppressed hyperon production off nuclei induced by antineutrinos
M. Benitez Galan🇪🇸 · L. Alvarez-Ruso🇪🇸 · M. Rafi Alam🇮🇳 · I. Ruiz Simo🇪🇸 · M.J. Vicente Vacas🇪🇸
In this work we study the production of $Σ$ and $Λ$ hyperons in strangeness changing $Δ S = - 1$ charged current interactions of muon antineutrinos on nuclear targets. At the nucleon level, besides quasielastic scattering we consider the inelastic mechanism in which a pion is produced alongside the hyperon. Its relevance for antineutrinos with energies below 2 GeV is conveyed in integrated and differential cross sections. We observe that the distributions on the angle between the hyperon and the final lepton are clearly different for quasielastic and inelastic processes. Hyperon final state interactions, modeled with an intranuclear cascade, lead to a significant transfer from primary produced $Σ$ 's into final $Λ$ 's. They also cause considerable energy loss, which is apparent in hyperon energy distributions. We have investigated $Λ$ production off $^{40}$ Ar in the conditions of the recently reported MicroBooNE measurement. We find that the $Λ π$ contribution, dominated by $Σ^{*} (1385)$ excitation, accounts for about one third of the cross section.
Comments:
13 pages, 5 figures, 1 table, several new references added. Inclusion of Lambda-nucleus potential in the final state interaction. This version matches the accepted version for publication in Physical Review D
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2305.17004 [pdf]
PRD(2024)·4 citations

Affiliations

first authorsco-authorsvia INSPIRE