PaperPanorama
FAQ

Nuclear Theory·nucl-th

Friday·January 16, 2026

10 papers—7 primary·3 cross-listed

All10Primary7Cross-lists3
  1. 01

    The collectivity of transverse momentum fluctuations

    Tribhuban Parida🇮🇳 · Rupam Samanta🇵🇱 · Jean-Yves Ollitrault🇫🇷

    We study the observable , which quantifies the relative change of spectra induced by event-by-event density fluctuations in the medium created in heavy-ion collisions. This quantity provides a direct measure of radial flow and serves as a probe of collectivity, complementing anisotropic flow coefficients. Using hydrodynamic model calculations, we predict the behavior of and show that the scaled quantity exhibits very little dependence on centrality and transport coefficients. We further find that the apparent influence of transport coefficientsparticularly bulk viscosity on largely originates from modifications of the event-averaged mean transverse momentum, . By expressing as a function of , the genuine sensitivity of to transport coefficients can be isolated. Moreover, since is the -differential measure of event-by-event fluctuations, it naturally explains the observed -cut dependence of measured by ATLAS collaboration.

    nucl-thhep-phnucl-exEPJ Web Conf.(2026)·0 citations
  2. 02

    Average pairing correlation properties and effective pairing residual interactions

    Meng-Hock Koh🇲🇾 · P. Quentin🇫🇷 · L. Bonneau🇫🇷

    This paper describes a method to determine the intensities of effective pairing residual interactions, extending what has been done for the seniority force model [Phys. Rev. C 110, 024311 (2024)]. It has been tested in Hartree-Fock plus BCS calculations using residual pairing zero-range interactions. The average pair condensation energy is the key quantity connecting the determination of constant pairing matrix elements to the estimation of delta interaction intensities. From individually fitted delta pairing strengths of well and rigidly deformed nuclei whose proton number ranges from to evaluated at the ground-state, we have determined average interaction intensities. They reproduce equally well the data on MoI as what is obtained within the seniority force ansatz with a r.m.s. deviation of about . This approach provides a non-ambiguous way to determine reasonably well the strengths of pairing interactions at the ground-state of well deformed nuclei. It allows to perform, with some reasonable level of confidence, calculations for other nuclei in the corresponding nuclear region as well as beyond their ground states in particular to assess deformation properties as, e.g., to evaluate fission barriers or spectral properties of quasi-particle states.

    nucl-th0 citations
  3. 03

    Revisiting the nuclear island of negative hexadecapole deformations in A180 mass region: focusing on moments of inertia and quadrupole-hexadecapole coupling

    Ran Li · Hua-Lei Wang · Kui Xiao · Zhen-Zhen Zhang · Min-Liang Liu

    For even-even nuclei Yb, Hf and W located on an island of hexadecapole-deformation archipelago, the structure properties, especially under rotation, are reinvestigated by using the Hartree-Fock-Bogliubov-Cranking (HFBC) calculation with a fixed shape (e.g., the ground-state equilibrium shape). The equilibrium deformations, extracted from the potential energy surface, are calculated based on the phenomenological Woods-Saxon mean-field Hamiltonian within the framework of macroscopic-microscopic (MM) model. The impact of different deformation degrees of freedom on, e.g., single-particle levels, total energy, and moment of inertia, is revealed, especially concentrating on the hexadecapole-deformation effects and the quadrupole-hexadecapole coupling. Considering the axially hexadecapole deformation, the present calculations can well reproduce available experimental data, including the quadrupole deformations and moments of inertia. Interestingly, it is found that the impact of different deformation degrees of freedom on moment of inertia exhibits a similar trend in the HFBC and rigid-body calculations though the latter ignores the pairing effects. Before starting or constructing a complex theory-model, to some extent, such a similarity can provide an alternative way of understanding the effect of, e.g., exotic deformations, on moment of inertia by the calculation of a simple rigid-body approximation. The present findings could offer insights into the static and dynamic effects of hexadecapole deformations, contributing valuable information for the corresponding research in nuclear structure and reaction.

    nucl-thCommun.Theor.Phys.(2026)·0 citations
  4. 04

    Quadrupole transitions of C and their isospin symmetry with Be

    Takayuki Myo · Mengjiao Lyu · Qing Zhao · Masahiro Isaka · Niu Wan · Hiroki Takemoto · Hisashi Horiuchi · Hiroshi Toki · Akinobu Doté

    We investigate the structures of C focusing on the quadrupole properties in comparison with the mirror nucleus Be. We describe C and Be in the variation of the multiple bases of the antisymmetrized molecular dynamics (AMD), in which the multiple AMD bases are optimized simultaneously in the total-energy variation. In the monopole transitions, we confirm the isospin symmetry between C and Be by exchanging protons and neutrons. In the quadrupole transitions, most cases show larger values in C than those of Be, except for the transition of . The transition of shows similar values in the two nuclei in spite of the different proton numbers, which agrees with the experimental situation as an anomaly. This relation comes from the small proton deformation in C due to its subclosed nature and the large proton deformation in Be due to two- clustering. This property can also be seen in the quadrupole moments of the two nuclei. In the neutron deformations of C and Be, the opposite tendency of protons is confirmed and these results ensure the isospin symmetry between the two nuclei. We also confirm the large quadrupole transitions between the elongated linear-chain states. It would be desirable for future experiments to investigate the present characteristics of the transitions in the two nuclei.

    nucl-thnucl-exPRC(2026)·1 citation
  5. 05

    Updated Results for Kinematic Factors in Double Beta Decays

    S. Ghinescu🇷🇴 · S. Stoica🇷🇴

    Accurate calculations of phase space factors (PSFs), electron energy spectra and angular correlations are essential for designing and interpreting double-beta decay (DBD) experiments. These quantities help maximize sensitivity to potential signals, distinguish between different decay modes and interpret the data. In this work we provide updated results for these kinematic factors for two-neutrino () and neutrinoless () decay modes, including electron-emission, positron-emission and electron capture transitions. The calculations are performed with an adapted Dirac-Hartree-Fock-Slater method which allows for orthogonality of the wave functions of electrons and positrons in bound and continuum states and incorporates relevant atomic features such us screening, finite nuclear size, exchange corrections and phase shift effects. We provide tables with updated PSFs calculated both in the closure approximation and using the Taylor expansion method, for a large number of DBD isotopes. We discuss the impact of individual atomic corrections and find that our results are in line with predictions reported in recent literature. In some specific cases we find differences between our PSF values and those previously reported which are worth considering for better prediction and interpretation of DBD data. Then, we provide numerical values for , , and , which are most investigated in current DBD experiments. Similar data for other isotopes are available upon request.

    nucl-thEPJC(2026)·1 citation
  6. 06

    Islands of shape coexistence for Z=38-84 in a non-relativistic mean-field approach using Hartree-Fock-Bogoliubov theory

    Malik A. Hasan · Dennis Bonatsos

    Based on the microscopic mechanism of the particle-hole (p-h) excitations in the proton and neutron single-particle energy levels relative to the Fermi energy, a search for islands of shape coexistence (SC) is performed over a wide range of even-even nuclei from Z=38 to 84 using non-relativistic self-consistent mean-field with the Hartree-Fock-Bogoliubov (HFB) theory using the Skyrme-SKI3 functional. The results of the present study show that neutron-induced islands of SC, corresponding to proton p-h excitations, are found around the magic numbers Z=82 and Z=50, centered at the relevant neutron midshells of N=104 and N=66 respectively, while proton-induced islands of SC, corresponding to neutron p-h excitations, are found around the neutron numbers N=90 and N=60, centered at the relevant proton midshells Z=66 and Z=38 respectively. In addition, islands of SC due to both neutron and proton particle-hole excitations are found around N=40, Z=40. The results of the present study are compared with the results of covariant density functional theory using the DDME2 functional, using the same p-h mechanism. The islands of SC that appeared in the CDFT work with the DDME2 functional are corroborated by the present study with the Skyrme-SKI3 functional, thus confirming the robustness of the particle-hole excitations mechanism in searching for islands of SC. In addition, the current study revealed new regions of SC, adjacent to the earlier islands and expanding their shores.

    nucl-thPRC(2026)·1 citation
  7. 07

    The Effective Theory of Muon-to-Electron Conversion

    W. C. Haxton🇺🇸 · Evan Rule🇺🇸

    We summarize recent work to develop an effective theory of muon-to-electron conversion, based on a complete set of low-energy effective operators that are developed from a systematic expansion in velocities and momenta. The expansion effectively factors rates into sums of particle physics and nuclear physics terms, where the former are expressed as bilinears in the LECs (the low-energy constants of the effective theory) and the latter are the associated nuclear responses. One can view the nuclear responses as ``dials" that can be adjusted -- for example, by selection of targets with specific properties -- in order to isolate the former. We show that an important dial, in the case of Mu2e and COMET, will be inelastic transitions to certain low-energy nuclear states that are resolvable in 27Al. If these transitions are exploited, the experiments have the potential not only to discover charged lepton flavor violation (CLFV), but to determine the operators responsible for the CLFV. We also discuss how such low-energy results can be ``ported" to higher energies through a tower of matched EFTs, so they can be combined with other experimental limits to further constrain CLFV

    nucl-thhep-exhep-phnucl-ex0 citations

Affiliations

first authorsco-authorsvia INSPIRE