Nuclear Theory·nucl-th

Thursday·July 11, 2024

10 papers—3 primary·7 cross-listed

01
[Submitted on 22 Jun 2024]
Mean-field derived IBM-1 Hamiltonian with intrinsic triaxial deformation
Polytimos Vasileiou (1) · Dennis Bonatsos (2) · Theo J. Mertzimekis (1) ((1) Department of Physics, National & Kapodistrian University of Athens, Zografou Campus, Greece, (2) Institute of Nuclear and Particle Physics, National Center for Scientific Research "Demokritos'', Aghia Paraskevi, Greece)
An interacting-boson-model-1 (IBM-1) Hamiltonian, derived from self-consistent mean-field calculations using a Skyrme energy density functional is employed for the study of energy spectra and $B (E 2)$ transition strengths in the even-even $^{162 - 184} Hf$ and $^{168 - 186} W$ . An intrinsic triaxial deformation, derived from fermionic proxy-SU(3) irreps, is incorporated into the IBM-1 potential energy curve, which is subsequently mapped to the fermionic one, in order to derive the parameters of the IBM-1 Hamiltonian. It is shown that the inclusion of the intrinsic triaxial deformation derived from the proxy-SU(3) irreps leads to a significantly improved agreement between the theoretical predictions and experimental data for the low-lying quadrupole bands in the examined isotopes, without the need of higher-order terms in the IBM-1 Hamiltonian. The calculated $B (E 2)$ transition strengths are also improved, compared to the axially symmetric case. The recently suggested preponderance of triaxial deformation over extended regions of the nuclear chart is obtained as a by-product. Future potential improvements and extensions to this mapping approach are also discussed.
Comments:
20 pages, 9 figures. Accepted for publication to Phys. Rev. C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2407.07101 [pdf]
PRC(2024)·6 citations
02
[Submitted on 9 Jul 2024]
Triply-heavy/strange baryons with Cornell potential on a quantum computer
Nicolás Martínez de Arenaza🇪🇸 · Juan J. Gálvez-Viruet🇪🇸 · Felipe J. Llanes-Estrada (Univ. Complutense de Madrid)🇪🇸
We present a computation of triply-heavy baryons on a quantum computer, employing the Cornell quark model in line with the earlier quarkonium work of Gallimore and Liao. These baryons are some of the most interesting Standard Model particles which have not yet been detected, as they bear on the short range (colour) behaviour of the nuclear force. The spectrum here obtained is compatible with predictions from earlier works, with our uncertainty dominated by traditional few-body approximations (size of the variational basis, center of mass recoil, parameter estimation...) and not by the statistical error from the quantum computer (deployed here as a small diagonalizer), which turns out to be negligible respect to the other sources of uncertainty, at least in the present unsophisticated few-body approximation. We have also substituted one or more heavy quarks for strange quarks.
Comments:
16 pages, 7 plots, uses quantikz2
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2407.07232 [pdf]
EPJA(2024)·11 citations
03
[Submitted on 8 Jul 2024]
Angular anisotropy of secondary neutron spectra in $^{232}$ Th+n
V.M. Maslov
Neutron emission spectra (NES) of $^{232}$ Th+n interaction provide strong evidence of angular anisotropy of secondary neutron emission, another evidence might be predicted in $^{232}$ Th%(n,F)% prompt fission neutron spectra (PFNS). In case of NES observed angular anisotropy is presumably due to angular dependence of elastic scattering, direct excitation of collective levels and preequilibrium emission of (n,nX) neutrons. In $^{232}$ Th+n direct excitation data analysis, ground state band levels are coupled within rigid rotator model, while those of beta bands, gamma bands and octupole band theta are coupled within soft deformable rotator model. NES of $^{232}$ Th+n at En of 6, 12, 14, 18 MeV exhaustively described. The net effect of these procedures for En up to 20 MeV is the adequate approximation of angular distributions of $^{232}$ Th $(n, n X)$ first neutron inelastic scattering in continuum, which corresponds to U of 1.2-6 MeV excitations of $^{232}$ Th. The contribution of $^{232}$ Th $(n, F)$ PFNS to the NES is exceptionally low. PFNS anisotropy occurs because some portion of $(n, n X)$ neutrons might be involved in exclusive prefission neutron spectra. In $^{232}$ Th $(n, x n f)$ reactions PFNS demonstrate different response to forward and backward (n,xnf) neutron emission relative to the incident neutron momentum, when compared with $^{235}$ U $(n, x n f)$ or 239Pu(n,xnf) reactions. Average energy of (n,xnf) neutrons depends on the neutron emission angle theta, i.e. fission cross section, prompt neutron number and total kinetic energy are shown to vary with the angle theta as well. Exclusive neutron spectra ( $n, x n f)$ at theta equal to 90 degrees are consistent with observed $^{232}$ Th $(n, F)$ and $^{232}$ Th $(n, x n)$ reaction cross sections within En from 1 to 20 MeV energy range.
Comments:
16 pages, 8 figures. arXiv admin note: text overlap with arXiv:2407.06242
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2407.07274 [pdf]
0 citations
04
[Submitted on 2 Jul 2024] (cross-list from hep-ph)
Coherent photo- and electroproduction of charmonia on nuclear targets revisited: Green function formalism
J. Nemchik🇨🇿 · J. Óbertová🇨🇿
We study for the first time the production of charmonia in nuclear ultra-peripheral and electron-ion collisions based on a rigorous Green function formalism. Such formalism allows to incorporate properly formation effects (color transparency), as well as the quantum coherence inherent in higher twist shadowing corrections related to the $∣ Q Q ˉ ⟩$ Fock component of the photon. The leading twist gluon shadowing associated with multi-gluon photon fluctuations is also included within the same formalism. The later effect represents the dominant source of shadowing at mid rapidities in the LHC kinematic region, while the reduced effect of quark shadowing leads to a significant modification of differential cross sections $d σ / d y$ at forward and/or backwards rapidities. Model calculations for $d σ / d y$ are in a good agreement with available UPC data on coherent charmonium production at RHIC and the LHC. In addition, we also perform predictions for nuclear effects in the electroproduction of charmonia, which can be verified by new data from electron-ion colliders.
Comments:
16 pages, 6 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2407.02219 [pdf]
PRD(2024)·3 citations
05
[Submitted on 9 Jul 2024] (cross-list from astro-ph.HE)
The neutron star mass, distance, and inclination from precision timing of the brilliant millisecond pulsar J0437 $-$ 4715
Daniel J. Reardon · Matthew Bailes · Ryan M. Shannon · Chris Flynn · Jacob Askew · N. D. Ramesh Bhat · Zu-Cheng Chen · Małgorzata Curyło · Yi Feng · George B. Hobbs · Agastya Kapur · Matthew Kerr and 8 other authors
The observation of neutron stars enables the otherwise impossible study of fundamental physical processes. The timing of binary radio pulsars is particularly powerful, as it enables precise characterization of their (three-dimensional) positions and orbits. PSR~J0437 $-$ 4715 is an important millisecond pulsar for timing array experiments and is also a primary target for the Neutron Star Interior Composition Explorer (NICER). The main aim of the NICER mission is to constrain the neutron star equation of state by inferring the compactness ( $M_{p} / R$ ) of the star. Direct measurements of the mass $M_{p}$ from pulsar timing therefore substantially improve constraints on the radius $R$ and the equation of state. Here we use observations spanning 26 years from Murriyang, the 64-m Parkes radio telescope, to improve the timing model for this pulsar. Among the new precise measurements are the pulsar mass $M_{p} = 1.418 \pm 0.044$ $M_{⊙}$ , distance $D = 156.96 \pm 0.11$ pc, and orbital inclination angle $i = 137.506 \pm 0.01 6^{\circ}$ , which can be used to inform the X-ray pulse profile models inferred from NICER observations. We demonstrate that these results are consistent between multiple data sets from the Parkes Pulsar Timing Array (PPTA), each modeled with different noise assumptions. Using the longest available PPTA data set, we measure an apparent second derivative of the pulsar spin frequency and discuss how this can be explained either by kinematic effects due to the proper motion and radial velocity of the pulsar or excess low-frequency noise such as a gravitational-wave background.
Comments:
13 pages, 3 figures, accepted for publication in Astrophysical Journal Letters
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th)
arXiv:
2407.07132 [pdf]
ApJL(2024)·86 citations
06
[Submitted on 9 Jul 2024] (cross-list from hep-ph)
Estimating centrality in heavy-ion collisions using Transfer Learning technique
Dipankar Basak🇮🇳 · Kalyan Dey🇮🇳
In this study, we explore the applicability of Transfer Learning techniques for estimating collision centrality in terms of the number of participants ( $N_{part}$ ) in high-energy heavy-ion collisions. In the present work, we leverage popular pre-trained CNN models such as VGG16, ResNet50, and DenseNet121 to determine $N_{part}$ in Au+Au collisions at $s = 200$ GeV on an event-by-event basis. Remarkably, all three models achieved good performance despite the pre-trained models being trained for databases of other domains. Particularly noteworthy is the superior performance of the VGG16 model, showcasing the potential of transfer learning techniques for extracting diverse observables from heavy-ion collision data.
Comments:
14 pages, 10 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2407.07210 [pdf]
NPA(2025)·1 citation
07
[Submitted on 10 Jul 2024] (cross-list from nucl-ex)
The Proton Electromagnetic Generalized Polarizabilities
Nikos Sparveris🇺🇸
The electromagnetic polarizabilities are fundamental properties of the proton that characterize its response to an external EM field. The generalization of the EM polarizabilities to non-zero four-momentum transfer opens up a powerful path to study the internal structure of the proton. They map out the spatial distribution of the polarization densities in the proton, provide access to key dynamical mechanisms that contribute to the electric and the magnetic polarizability effects, and allow to determine fundamental characteristics of the system, such as the electric and the magnetic polarizability radii. This article reviews the knowledge of the proton EM generalized polarizabilities. An introduction is given to the basic concepts and to the theoretical framework, that is then followed by a discussion that emphasizes the recent developments and findings of the Virtual Compton scattering experiments and future perspectives on the topic.
Comments:
Review Article, Frontiers in Physics
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2407.07597 [pdf]
Front.Phys.(2024)·2 citations
08
[Submitted on 10 Jul 2024] (cross-list from astro-ph.HE)
Bayesian Inference of Fine-Features of Nuclear Equation of State from Future Neutron Star Radius Measurements to 0.1km Accuracy
Bao-An Li🇺🇸 · Xavier Grundler🇺🇸 · Wen-Jie Xie🇺🇸 · Nai-Bo Zhang🇺🇸
To more precisely constrain the Equation of State (EOS) of supradense neutron-rich nuclear matter, future high-precision X-ray and gravitational wave observatories are proposed to measure the radii of neutron stars (NSs) with an accuracy better than about 0.1 km. However, it remains unclear what particular aspects (other than the stiffness generally spoken of in the literature) of the EOS and to what precision they will be better constrained. In this work, within a Bayesian framework using a meta-model EOS for NSs, we infer the posterior probability distribution functions (PDFs) of incompressibility $K_{0}$ and skewness $J_{0}$ of symmetric nuclear matter (SNM) as well as the slope $L$ , curvature $K_{sym}$ , and skewness $J_{sym}$ characterizing the density dependence of nuclear symmetry energy $E_{sym} (ρ)$ , respectively, from mean values of NS radii consistent with existing observations and an expected accuracy $Δ R$ ranging from about 1.0 km to 0.1 km. We found that (1) the $Δ R$ has little effect on inferring the stiffness of SNM at suprasaturation densities, (2) smaller $Δ R$ reveals more accurately not only the PDFs but also pairwise correlations among parameters characterizing high-density $E_{sym} (ρ)$ , (3) a double-peak feature of the PDF( $K_{sym}$ ) corresponding to the strong $K_{sym} - J_{sym}$ and $K_{sym} - L$ anti-correlations is revealed when $Δ R$ is less than about 0.2 km, and the locations of the two peaks are sensitive to the maximum value of $J_{sym}$ reflecting the stiffness of $E_{sym} (ρ)$ above about 3 times the saturation density $ρ_{0}$ of SNM, (4) the high-precision radius measurement for canonical NSs is more useful than that for massive ones for constraining the EOS of nucleonic matter around $(2 - 3) ρ_{0}$ .
Comments:
34 pages with additional results, discussions and appendices. Phys. Rev. D in press
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2407.07823 [pdf]
PRD(2024)·28 citations
09
[Submitted on 10 Jul 2024] (cross-list from hep-ph)
Inhibition of splitting of the chiral and deconfinement transition due to rotation in QCD: the phase diagram of linear sigma model coupled to Polyakov loop
Pracheta Singha🇷🇴 · Victor E. Ambrus🇷🇴 · Maxim N. Chernodub🇷🇴
We discuss the effect of rigid rotation on the critical temperatures of deconfinement and chiral transitions in the linear sigma model coupled to quarks and the Polyakov loop. We point out the essential role of the causality condition, which requires that any point of the system should rotate slower than the velocity of light. We show that imposing this physical requirement leads to inhibition of the splitting between the chiral and confining transitions, which becomes negligibly small ({\Delta}T ~ 1 MeV or less) for experimentally relevant, slow angular velocities {\Omega} ~ 10 MeV of a 5-10 fm-sized systems. Moreover, the boundedness of the system has a much bigger effect on temperature splitting than the rotation itself: the splitting reaches 10 MeV in a small, one-fermi-sized non-rotating system. The temperature splitting may, however, become enhanced in an academic limit of ultra-relativistic regimes when the boundary of the system rotates at near-to-light velocities.
Comments:
18 pages, 8 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2407.07828 [pdf]
PRD(2024)·21 citations
10
[Submitted on 10 Jul 2024] (cross-list from astro-ph.HE)
Probe and Prejudice: Classification of compact objects and model comparison using EOS knowledge
Hauke Koehn🇩🇪 · Thibeau Wouters🇳🇱 · Henrik Rose🇩🇪 · Peter T. H. Pang🇳🇱 · Rahul Somasundaram🇺🇸 · Ingo Tews🇺🇸 · Tim Dietrich🇩🇪
Nuclear theory and experiments, alongside astrophysical observations, constrain the equation of state (EOS) of supranuclear-dense matter. Conversely, knowledge of the EOS allows an improved interpretation of nuclear or astrophysical data. In this article, we use several established constraints on the EOS and the new NICER measurement of PSR J0437-4715 to comment on the nature of the primary companion in GW230529 and the companion of PSR J0514-4002E. We find that, with a probability of $≳ 84%$ and $≳ 68%$ , respectively, both objects are black holes. These likelihoods increase to above $95%$ when one uses GW170817's remnant as an upper limit on the TOV mass. We also demonstrate that the current knowledge of the EOS substantially disfavors high masses and radii for PSR J0030+0451, inferred recently when combining NICER with XMM-Newton background data and using particular hot-spot models. Finally, we also use our obtained EOS knowledge to comment on measurements of the nuclear symmetry energy, finding that the large value predicted by the PREX-II measurement displays some mild tension with other constraints on the EOS.
Comments:
14 pages, 5 figures, published in PRD, v3 contains minor correction for the Pb-208 dipole
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2407.07837 [pdf]
PRD(2024)·16 citations

Affiliations

first authorsco-authorsvia INSPIRE