PaperPanorama

Nuclear Theory·nucl-th

Monday·September 15, 2025

6 papers—3 primary·3 cross-listed

All6Primary3Cross-lists3
  1. 01

    SU(3) rigid triaxiality in Sm

    Chunxiao Zhou · Xue Shang · Tao Wang

    The Sm nucleus, which has long been regarded as a typical quantum system exhibiting axial symmetry, has been recently suggested to exhibit a small degree of triaxiality by Otsuka \textit{et al.}. This small triaxiality was recently observed using the decay of the Sm isovector giant dipole resonance. Thus further studying this small triaxiality is very necessary for understanding the nature of the collectivity in nuclei. In this paper, the rigid triaxiality in Sm is investigated using the newly proposed SU3-IBM theory. If the irreducible representation (irrep) of the ground state is (18,2) in the SU(3) symmetry limit, the new model can effectively reproduce the experimental data of Sm, showing good agreements with realistic energy spectra, B(E2) values, and quadrupole moments. This result further confirms the vality of the SU3-IBM for the description of the rigid triaxiality in realistic nuclei, and reveals the SU(3) dominance of the collectivity motions in nuclei.

    nucl-th2 citations
  2. 02

    Nuclear chiral density wave in neutron stars?

    Orestis Papadopoulos🇬🇧 · Andreas Schmitt🇬🇧

    Anisotropic phases potentially play a role in the internal composition of neutron stars, the main laboratory for the phase structure of QCD at high baryon densities. We review the study of such a phase, the chiral density wave, within a phenomenological nucleon-meson model, including nucleonic vacuum fluctuations within a renormalization scheme recently developed. Neutron stars in this model and within our approximations either do not contain a chiral density wave core or they are too light to agree with observations.

    nucl-thastro-ph.HEhep-phJ.Subatomic Part.Cosmol.(2025)·5 citations
  3. 03

    Effective Mass in Quantum Hadrodynamics-I and its Impact on the Equation of State of Neutron Matter

    Ghitha Nadhira Azka Rahiemy🇮🇩 · Eko Tri Sulistyani🇮🇩 · Pekik Nurwantoro🇮🇩

    The effective nucleon mass (M^*) plays a central role in Quantum Hadrodynamics-I (QHD-I), linking scalar meson interactions at the microscopic level to the macroscopic properties of dense nuclear matter. In this work, we re-derive the scalar density integral in detail and validate it numerically using Gaussian quadrature. The numerical and analytic results are found to be in excellent agreement, confirming the robustness of both approaches. We then investigate the sensitivity of M^* to different parameter sets, highlighting its strong influence on nuclear saturation, compressibility, and the resulting equation of state (EoS). The analysis shows that variations in meson-nucleon couplings propagate directly into differences in pressure and energy density, affecting the stiffness of the EoS. While QHD-I produces characteristically stiff EoS, the effective mass evaluation provides a transparent framework for connecting microscopic meson dynamics to macroscopic neutron star properties. These findings underline the relevance of M^* as a microscopic-macroscopic bridge and demonstrate the utility of numerical methods for extending relativistic mean-field models in nuclear astrophysics.

    nucl-thastro-ph.HE0 citations
  4. 04

    Extraction of neutron-capture cross sections on Zr using the charge-exchange Oslo method

    N.D. Pathirana · R.G.T. Zegers · B. Gao · A. Spyrou · A.C. Larsen · H. Berg · D. Bazin · H.L. Crawford · A. Gade · P. Gastis · T. Ginter · C.J. Guess and 7 other authors

    The Nb(,He) reaction at 115 MeV/u was studied to demonstrate that nuclear level densities and -ray strength functions can be extracted from charge-exchange reactions at intermediate energies using the Oslo technique. The matrix of excitation energy in Zr, reconstructed from the (,He) reaction, versus the energy of rays emitted by the excited Zr nuclei, was obtained in an experiment with the S800 Spectrograph operated in coincidence with the GRETINA -ray detector. The extracted level density and -ray strength function obtained by applying the Oslo method to this matrix were used to estimate the Zr(,)Zr cross section by combining the new results with other experimental data and theoretical calculations for 1 and 1 strength functions at higher energies. Good agreement with direct measurements of the Zr(,)Zr cross section was found. The contribution from the upbend in the extracted -ray strength function was important to achieve the consistency as the neutron-capture cross section without this contribution is significantly below the direct measurements otherwise. Since charge-exchange reactions at intermediate energies have long been used for extracting Gamow-Teller strengths, the successful demonstration of the charge-exchange Oslo method enables experiments in which (,) cross sections and Gamow-Teller strengths can be measured simultaneously, which is of benefit for astrophysical studies.

    ↳ nucl-exastro-ph.SRnucl-thPRC(2026)·1 citation
  5. 05

    Gluon splitting rates in an anisotropic plasma in the AMY formalism

    Florian Lindenbauer🇦🇹

    We introduce a novel numerical method to obtain the gluon splitting rates in an anisotropic QCD plasma in the AMY formalism, suitable for an anisotropic collision kernel. The method extends previous works by decomposing the additional angular information into Fourier modes, resulting in a significantly larger system of differential equations to solve numerically. It is then tested by calculating the rates for a simple anisotropic model for the collision kernel, which is compared to a thermal system. Remarkably, the obtained rates can be well-approximated by the rates calculated from an angular-averaged collision kernel, while still deviating significantly from equilibrium. An isotropic model for the collision kernel that is commonly used in QCD kinetic theory simulations, and which relies on the infrared temperature and an effective Debye mass, leads to rates that significantly deviate from the nonequilibrium rate, particularly at smaller parton energies.

    ↳ hep-phnucl-th6 citations
  6. 06

    Pseudogauge ambiguity in the distributions of energy density, pressure, and shear force inside the nucleon

    Kenji Fukushima🇯🇵 · Tomoya Uji🇯🇵

    We study the spatial distributions of pressure, energy density, and shear forces inside the nucleon within the two-flavor Skyrme model including vector mesons. This framework has the advantage that nucleon configurations can be stabilized without the Skyrme term. In contrast to the model without vector mesons, however, we realize that the energy-momentum tensor (EMT) becomes pseudo-gauge dependent. We explicitly demonstrate that all these distributions differ between the canonical and Belinfante forms of the EMTs. We identify the pseudo-gauge ambiguity as originating from nonvanishing surface terms associated with spin currents generated by the vector-meson field strength tensors. Furthermore, we show that the pressure and shear-force distributions in the canonical EMT develop singularities at the nucleon center, whereas the corresponding Belinfante distributions remain finite. Finally, we discuss the implications of pseudo-gauge dependence for extracting the confining force and for constructing the equation of state inside the nucleon.

    ↳ hep-phnucl-thPRD(2026)·6 citations

Affiliations

first authorsco-authorsvia INSPIRE