PaperPanorama
FAQ

Nuclear Theory·nucl-th

Monday·September 25, 2023

8 papers—6 primary·2 cross-listed

All8Primary6Cross-lists2
  1. 01

    Constraints for the X17 boson from compacts objects observations

    A. Kanakis-Pegios🇬🇷 · V. Petousis🇨🇿 · M. Veselsky🇨🇿 · Jozef Leja🇸🇰 · Ch.C. Moustakidis🇬🇷

    We investigate the hypothetical X17 boson on neutron stars and Quark Stars (QSs) using various hadronic Equation of States (EoSs) with phenomenological or microscopic origin. Our aim is to set realistic constraints on its coupling constant and the mass scaling, with respect to causality and various possible upper mass limits and the dimensionless tidal deformability . In particular, we pay special attention on two main phenomenological parameters of the X17, the one is related to the coupling constant that it has with hadrons or quarks and the other with the in-medium effects through the regulator . Both are very crucial concerning the contribution on the total energy density and pressure. In the case of considering the X17 as a carrier of nuclear force in Relativistic Mean Field (RMF) theory, an admixture into vector boson segment was constrained by 20\% and 30\%. In our investigation, we came to the general conclusion that the effect of the hypothetical X17 both on neutron and QSs constrained mainly by the causality limit, which is a specific property of each EoS. Moreover, it depends on the interplay between the main two parameters that is the interaction coupling and the in-medium effects regulator . These effects are more pronounced in the case of QSs concerning all the bulk properties.

    nucl-thastro-ph.HEnucl-exPRD(2024)·13 citations
  2. 02

    Some Approaches to the Energy-Loss Straggling Calculation

    P. B. Kats (1) · A. V. Kudravets (1) · A. S. Rymasheuskaya (1) · O. O. Voskresenskaya (2) ((1) Brest State University · (2) Joint Institute for Nuclear Research)

    Some exact and approximate methods commonly used to calculate corrections to the Bethe stopping formula are modified and adapted by the authors to the calculation of the energy loss straggling. An intercomparison is carried out for results of approaches developed in the present work. An excellent agreement obtained between the results for ELS, calculated with an exact method previously proposed by one of the authors and the results of the Lindhard-Sorensen method for moderate relativistic energies. It is shown that some modified by authors approximate methods for the ELS calculating have the higher accuracy than the conventional approximate method of Lijian-Qing-Zhengming. So, in all the cases considered, the accuracy of the twice modified LQZ method in the ELS calculations is higher than the accuracy of the usual LQZ method. A thrice modified LQZ method was also suggested in this work. A number of shortened LQZ methods for the ELS calculating have been proposed and developed too.

    nucl-thphysics.comp-ph0 citations
  3. 03

    Generalized time-dependent generator coordinate method for induced fission dynamics

    B. Li · D. Vretenar · T. Nikšić · J. Zhao · P. W. Zhao · J. Meng

    The generalized time-dependent generator coordinate method (TD-GCM) is extended to include pairing correlations. The correlated GCM nuclear wave function is expressed in terms of time-dependent generator states and weight functions. The particle-hole channel of the effective interaction is determined by a Hamiltonian derived from an energy density functional, while pairing is treated dynamically in the standard BCS approximation with time-dependent pairing tensor and single-particle occupation probabilities. With the inclusion of pairing correlations, various time-dependent phenomena in open-shell nuclei can be described more realistically. The model is applied to the description of saddle-to-scission dynamics of induced fission. The generalized TDGCM charge yields and total kinetic energy distribution for the fission of 240Pu, are compared to those obtained using the standard time-dependent density functional theory (TD-DFT) approach, and with available data.

    nucl-thFront.Phys.(2024)·23 citations
  4. 04

    Connection of four-dimensional Langevin model and Hauser-Feshbach theory to describe statistical decay of fission fragments

    Kazuki Fujio · Shin Okumura · Chikako Ishizuka · Satoshi Chiba · Tatsuya Katabuchi

    We developed a method superposing two different fission modes calculated in a four-dimensional Langevin model to obtain more accurate fission fragment yield and total kinetic energy (TKE). The two fission modes correspond to the standard I and standard II modes reported by Brosa et al., and parameters in the Langevin model and the superposing ratio were determined to reproduce the fission fragment yield of Pu of spontaneous fission. We also investigated the fission fragment yields and the TKEs of other Pu isotopes by using the same Langevin parameters and different superposing ratios, such as spontaneous fission of Pu and neutron-induced fission of Pu. The prompt fission observables, such as the neutron multiplicity, the prompt fission neutron spectrum, and the independent fission product yield were calculated in the Hauser-Feshbach statistical decay model implemented in a nuclear reaction code TALYS with Pu(n,f) in the incident energies ranging from thermal energy up to 5 MeV. The calculated fission observables qualitatively reproduce several known trends while calculated results have quantitative discrepancies between reported data. Although more improvements are needed for the most important nuclides, it turned out that our approach has the capability to provide prompt fission observables for difficult-to-measure nuclides.

    nucl-thJ.Nucl.Sci.Tech.(2024)·8 citations
  5. 05

    Pionic Final State Interactions and the Hypertriton Lifetime

    Fabian Hildenbrand🇩🇪 · Hans-Werner Hammer🇩🇪

    We analyze the contribution of pionic final state interactions (FSI) in the weak decay of the hypertriton. Focusing on the He channel, we find a contribution of the pionic FSI of the order of . Assuming a fixed value for the branching ratio for the decay width into He over the decay width into He and final states, we find values for the hypertriton lifetime that are consistent with the world average as well as recent measurements by the ALICE Collaboration.

    nucl-thhep-phEPJA(2023)·5 citations
  6. 06

    Study of neutron density fluctuation and neutron-proton correlation in Au+Au collisions using PYTHIA8/Angantyr

    Zhang Zuman🇨🇳 · Li Sha🇨🇳 · Yu Ning🇨🇳 · Lin Jianping🇨🇳 · Li Shuang🇨🇳 · Tang Siyu🇨🇳 · Zhou Daicui🇨🇳

    Utilizing the PYTHIA8 Angantyr model, which incorporates the multiple-parton interactions (MPI) based color reconnection (CR) mechanism, we study the relative neutron density fluctuation and neutron-proton correlation in Au+Au collisions at = 7.7, 11.5, 14.5, 19.6, 27, 39, 62.4, and 200 GeV. In this study, we have not only delved into the dependence of these two remarkable observations on rapidity, centrality, and energy, but also presented an analysis of their interplay with the MPI and CR. Our results have shown that the light nuclei yield ratio of proton, deuteron, and triton, expressed by the elegant expression , remains unchanged even as the rapidity coverage and collision centrality increase. Interestingly, we have also revealed that the effect of CR is entirely dependent on the presence of MPI; CR has no impact on the yield ratio if MPI is off. Our findings further demonstrate that the light nuclei yield ratio experiences a slight increase with increasing collision energy as predicted by the PYTHIA8 Angantyr model, but it cannot describe the non-monotonic trend observed by the STAR experiment. Based on the Angantyr model simulation results, it is essential not to overlook the correlation between neutron and proton fluctuations. The Angantyr model is a good baseline for studying collisions in the absence of a Quark-Gluon Plasma (QGP) system, given its lack of flow and jet quenching.

    nucl-thhep-phCPC(2023)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE