Nuclear Theory·nucl-th

Friday·December 6, 2024

10 papers—5 primary·5 cross-listed

01
[Submitted on 4 Dec 2024]
Robustness of the proxy-SU(3) symmetry in atomic nuclei and the role of the next highest weight irreducible representation
Dennis Bonatsos · Andriana Martinou · S.K. Peroulis · D. Petrellis · P. Vasileiou · T.J. Mertzimekis · N. Minkov
The proxy-SU(3) symmetry predicts, in a parameter-free way, the collective deformation variables beta and gamma in even-even atomic nuclei away from closed shells based on the highest weight irreducible representations (irreps) of SU(3) in the relevant proton and neutron shells, which are the most symmetric irreps allowed by the Pauli principle and the short-range nature of the nucleon-nucleon interactions. The special cases in which the use of the next highest weight irrep of SU(3) becomes necessary are pointed out and numerical results are given for several regions of the nuclear chart, which can be used as input for irrep-mixing calculations.
Comments:
31 pages, 14 figures, 6 tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2412.03692 [pdf]
Symmetry(2024)·7 citations
02
[Submitted on 4 Dec 2024]
A simple model to investigate jet quenching and correlated errors for centrality-dependent nuclear-modification factors in relativistic heavy-ion collisions
Ron A Soltz🇺🇸 · Dhanush A Hangal🇺🇸 · Aaron Angerami🇺🇸
We apply Bayesian techniques to compare a simple, empirical model for jet-quenching in heavy-ion collisions to centrality-dependent jet- $R_{AA}$ measured by ATLAS for Pb+Pb collisions at $s_{N N} = 5.02$ ~TeV. We find that the $R_{AA}$ values for central collisions are adequately described with a model for the mean $p_{T}$ -dependent jet energy-loss using only 2-parameters. This model is extended by incorporating 2D initial geometry information from TRENTO and compared to centrality-dependent $R_{AA}$ values. We find that the results are sensitive to value of the jet-quenching formation time, $τ_{f}$ , and that the optimal value of $τ_{f}$ varies with the assumed path-length dependence of the energy-loss. We construct a covariance error matrix for the data from the $p_{T}$ dependent contributions to the ATLAS systematic errors and perform Bayesian calibrations for several different assumptions for the systematic error correlations. We show that most-probable functions and $χ^{2}$ values are sensitive to assumptions made when fitting to correlated errors.
Comments:
13 pages, 16 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2412.03724 [pdf]
PRC(2025)·7 citations
03
[Submitted on 5 Dec 2024]
Radial Oscillations in Hybrid Stars with Slow Quark Phase Transition
Ishfaq Ahmad Rather🇩🇪 · Kauan D. Marquez🇵🇹 · Betânia C. Backes🇬🇧 · Grigoris Panotopoulos🇨🇱 · Ilídio Lopes🇵🇹
This study investigates the radial oscillations of hybrid neutron stars, characterized by a composition of hadronic external layers and a quark matter core. Utilizing a density-dependent relativistic mean-field model that incorporates hyperons and baryons for describing hadronic matter, and a density-dependent quark model for quark matter, we analyze the ten lowest eigenfrequencies and their corresponding oscillation functions. Our focus lies on neutron stars with equations-of-state involving N, N + $Δ$ , N + H, and N + H + $Δ$ , featuring a phase transition to quark matter. Emphasizing the effects of a slow phase transition at the hadron-quark interface, we observe that the maximum mass is attained before the fundamental mode's frequency decreases for slow phase transitions. This observation implies the stability of stellar configurations with higher central densities than the maximum mass, called Slow Stable Hybrid Stars (SSHSs), even under small radial perturbations. The length of these SSHS branch depends upon the energy density jump between two phases and the stiffness of the quark EoS.
Comments:
Contribution for the conference proceedings of the "10th International Conference on Quarks and Nuclear Physics (QNP 2024)"
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
arXiv:
2412.04007 [pdf]
PoS(2025)·0 citations
04
[Submitted on 5 Dec 2024]
Spin distribution of fission fragments involving bending and wriggling modes
D.E. Lyubashevsky · A.A. Pisklyukov · Yu.D. Shcherbina · T.Yu. Shashkina · P.V. Kostryukov
We present a closed analytical description of the spin distributions of the fragments produced in low-energy induced and spontaneous fission. In our model the high fragment spins and the relative orbital angular momentum arise from the zero-point transverse wriggling and bending oscillations of the two pre-fragments, under the postulate that the fissioning system remains ``cold'' up to scission -- its available energy being stored as non-equilibrium deformation rather than as heat. From the probability distributions of the two modes we derive a closed expression for the spin distribution of each fragment and for its mean value. The decisive quantities are the fragment moments of inertia, which we evaluate in the hydrodynamic model from the non-equilibrium scission deformations reconstructed from the measured prompt-neutron multiplicities. Confronted with the recent data on $^{232} Th (n, f)$ , $^{238} U (n, f)$ , and $^{252} Cf (sf)$ , the model reproduces both the magnitude of the mean spins and their characteristic sawtooth dependence on the fragment mass. Comparison with the statistical and microscopic approaches indicates that the differences for individual fragments can be traced largely to the deformation dependence of the moments of inertia.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2412.04410 [pdf]
Phys.Atom.Nucl.(2024)·3 citations
05
[Submitted on 5 Dec 2024]
Estimation of correlation coefficients and spin angular distributions of fission fragments
D.E. Lyubashevsky · A.A. Pisklyukov · S.V. Klyuchnikov · P.V. Kostryukov
This study proposes a theoretical model for studying the spin characteristics and angular correlations of fission fragments of heavy nuclei. The mechanisms of spin formation, including the influence of transverse vibrations, are considered and the relationship between the anisotropy of the angular distribution and the correlation coefficient is revealed. The theoretical predictions are compared with experimental data and various models developed by other research groups.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2412.04411 [pdf]
PRC(2025)·1 citation
06
[Submitted on 4 Dec 2024] (cross-list from hep-ph)
Giving wake to energy-energy correlators: Hydrodynamic response on the celestial sphere
João Barata🇨🇭 · Matvey V. Kuzmin🇷🇺 · José Guilherme Milhano🇵🇹 · Andrey V. Sadofyev🇵🇹
The observation of the medium response generated by the propagation of high energy partons in the quark gluon plasma produced in heavy-ion collisions would provide a clear and unmistakable evidence for the hydrodynamic behavior of the bulk. Recently, it has been argued that the features of the medium's back-reaction to the jet could be cleanly imprinted in the correlations of asymptotic energy flows, in principle allowing to isolate this signal from other uncorrelated physical processes. Nonetheless, the current limited theoretical understanding of these jet observables in heavy-ion collisions constrains their applicability as probes of the medium (hydro)dynamics. In this work, we provide an analytic picture for the medium back-reaction's effect on the energy flux and two point energy correlator. We show that the medium response leads to the emergence of an universal classical scaling law, competing with the perturbative QCD contribution at large angles. Comparing the associated correlator to recent experimental measurements, we find that the observed large angle features can be qualitatively described by a purely hydrodynamically driven response and its interplay with the hard jet component.
Comments:
9 pages, 3 figures; v3: updated DOI
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2412.03616 [pdf]
PRD(2025)·27 citations
07
[Submitted on 5 Dec 2024] (cross-list from nucl-ex)
Beta delayed neutron emission of $N = 84$ $^{132}$ Cd
M. Madurga🇺🇸 · Z.Y. Xu🇺🇸 · 1 R. Grzywacz🇺🇸 · M.R. Mumpower · A. Andreyev🇬🇧 · G. Benzoni🇮🇹 · M.J.G. Borge🇨🇭 · C. Costache🇷🇴 · I. Cox🇺🇸 · S. Cupp · B. Dimitrov🇧🇬 · P. Van Duppen🇧🇪 and 45 other authors
Using the time-of-flight technique, we measured the beta-delayed neutron emission of $^{132}$ Cd. From our large-scale shell model (LSSM) calculation using the N $^{3}$ LO interaction [Z.Y. Xu et al., Phys. Rev. Lett. 131, 022501 (2023)], we suggest the decay is dominated by the transformation of a neutron in the $g_{7/2}$ orbital, deep below the Fermi surface, into a proton in the $g_{9/2}$ orbital. We compare the beta-decay half-lives and neutron branching ratios of nuclei with $Z < 50$ and $N \geq 82$ obtained with our LSSM with those of leading "global" models such as Finite-Range Droplet Model (FRDM). Our calculations match known half-lives and neutron branching ratios well and suggest that current leading models overestimate the yet-to-be-measured half-lives. Our model, backed by the $^{132}$ Cd decay data presented here, offers robust predictive power for nuclei of astrophysical interest such as $r$ -process waiting points.
Comments:
8 pages, 6 figures
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2412.04333 [pdf]
PRL(2026)·0 citations
08
[Submitted on 5 Dec 2024] (cross-list from nucl-ex)
Disentangling the influence of excitation energy and compound nucleus angular momentum on fission fragment angular momentum
Simone Cannarozzo · Stephan Pomp · Andreas Solders · Ali Al-Adili · Zhihao Gao · Mattias Lantz · Heikki Penttilä · Anu Kankainen · Iain Moore · Tommi Eronen · Jouni Ruotsalainen · Zhuang Ge and 5 other authors
The origin of the large angular momenta observed for fission fragments is still a question under discussion. To address this, we study isomeric yield ratios (IYR), i.e. the relative population of two or more long-lived metastable states with different spins, of fission products. We report on IYR of 17 isotopes produced in the 28 MeV $α$ -induced fission of $^{232}$ Th at the IGISOL facility of the University of Jyväskylä. The fissioning nuclei in this reaction are $^{233, 234, 235}$ U*. We compare our data to IYR from thermal neutron-induced fission of $^{233}$ U and $^{235}$ U, and we observe statistically significant larger IYR in the $^{232}$ Th( $α$ ,f) reaction, where the average compound nucleus (CN) spin is 7.5 $ℏ$ , than in $^{233, 235}$ U(n $_{t h}$ ,f), with average spins 2.5 and 3.5 $ℏ$ , respectively. To assess the influence of the excitation energy, we study literature data of IYR from photon-induced fission reactions, and find that the IYR are independent of the CN excitation energy. We conclude that the different IYR must be explained by the different CN spin alone. This implies that the FF angular momentum only partly comes from the fission process itself, and is in addition influenced by the angular momentum present in the CN.
Comments:
Accepted for publication as a Letter in Physical Review C
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2412.04340 [pdf]
PRC(2025)·5 citations
09
[Submitted on 5 Dec 2024] (cross-list from astro-ph.HE)
Investigating the role of nuclear parameters in Neutron Star oscillations: a model comparison
Rajesh Maiti🇮🇳 · Debarati Chatterjee🇮🇳
Recent studies based on the relativistic mean field (RMF) model found certain nuclear empirical parameters, in particular the nucleon effective mass, to be strongly correlated with observable properties of Neutron Stars (NSs), such as the frequencies of $f -$ mode oscillations. This shows the potential to constrain the values of effective mass from future observations of $f -$ modes. One of our primary goals of this work is to investigate whether such correlations are physical or an artifact of the underlying nuclear model. To test this, we perform a comparative study of the correlations between NS astrophysical observables and nuclear physics parameters using two different equation of state models based on RMF theory and non-relativistic Meta-Modelling (MM) scheme. The nuclear meta-model does not assume any underlying nuclear model and therefore allows us to test the model dependence of the results. The calculations of the $f -$ mode characteristics are performed within the relativistic Cowling approximation. We use state-of-the-art nuclear microscopic calculations at low density and multi-messenger astrophysical data at high-density within a Bayesian-inspired scheme to constrain the parameter space of the nuclear models. From the posterior distribution, we probe the underlying correlations among nuclear parameters and with NS observables. We find that the correlation between the symmetry energy and its slope is physical, while that of the nucleon effective mass with NS observables is model-dependent. The study shows that the effective mass governs the high density behaviour in RMF models, while in the MM it is controlled by the higher order saturation parameters, and hence probes the possibility of constraining them from future $f$ -mode observations. The findings of this investigation are interesting both for astrophysics as well as nuclear physics communities.
Comments:
23 pages, 15 figures
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2412.04373 [pdf]
NPA(2026)·8 citations
10
[Submitted on 5 Dec 2024] (cross-list from hep-lat)
Block Lanczos algorithm for lattice QCD spectroscopy and matrix elements
Daniel C. Hackett🇺🇸 · Michael L. Wagman🇺🇸
Recent work introduced a new framework for analyzing correlation functions with improved convergence and signal-to-noise properties, as well as rigorous quantification of excited-state effects, based on the Lanczos algorithm and spurious eigenvalue filtering with the Cullum-Willoughby test. Here, we extend this framework to the analysis of correlation-function matrices built from multiple interpolating operators in lattice quantum chromodynamics (QCD) by constructing an oblique generalization of the block Lanczos algorithm, as well as a new physically motivated reformulation of the Cullum-Willoughby test that generalizes to block Lanczos straightforwardly. The resulting block Lanczos method directly extends generalized eigenvalue problem (GEVP) methods, which can be viewed as applying a single iteration of block Lanczos. Block Lanczos provides qualitative and quantitative advantages over GEVP methods analogous to the benefits of Lanczos over the standard effective mass, including faster convergence to ground- and excited-state energies, explicitly computable two-sided error bounds, straightforward extraction of matrix elements of external currents, and asymptotically constant signal-to-noise. No fits or statistical inference are required. Proof-of-principle calculations are performed for noiseless mock-data examples as well as two-by-two proton correlation-function matrices in lattice QCD.
Comments:
39+13 pages, 36 figures, 7 tables. v3: as published in PRD
Subjects:
High Energy Physics — Lattice (hep-lat); cs.NA (cs.NA); High Energy Physics — Phenomenology (hep-ph); math.NA (math.NA); Nuclear Theory (nucl-th)
arXiv:
2412.04444 [pdf]
PRD(2025)·33 citations

Affiliations

first authorsco-authorsvia INSPIRE