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Nuclear Theory·nucl-th

Thursday·November 20, 2025

10 papers—6 primary·4 cross-listed

All10Primary6Cross-lists4
  1. 01

    First order transition region of an equation of state for QCD with a critical point

    Jamie M. Karthein🇺🇸 · Volker Koch🇺🇸 · Claudia Ratti🇺🇸

    In addition to signals for the critical point, evidence for a first order phase transition would indicate a nontrivial structure within the QCD phase diagram. Moreover, while not a direct measurement of the critical point, the presence of a first order transition would imply its existence. This motivates the need to understand signatures of this first order transition in addition to directly studying the effect of a critical point. To this effect, we map the mean-field Ising model equation of state onto the QCD phase diagram, and reconstruct the full coexistence region in the case of a first order phase transition. Beyond the coexistence line, we maintain access to the spinodal region in the phase diagram, thus providing a description of metastable and unstable phases of matter. Thus, we describe the super-heated hadronic phase and the super-cooled quark-gluon plasma, which is useful for hydrodynamic simulations of the fireball created in a heavy-ion collision at low collision energy, where a first order phase transition is expected. We discuss the features of the pressure and other thermodynamic observables as functions of temperature and baryonic chemical potential, in particular their behavior in the coexistence region. Finally, we compare our equation of state to 3D Ising model ones available in the literature.

    nucl-thEPJ Web Conf.(2026)·0 citations
  2. 02

    Exploring highly-deformed ground states involving the second intruder orbit in Z>50 even-even nuclei

    Tsunenori Inakura · Wataru Horiuchi · Shin'ichiro Michimasa · Masaomi Tanaka

    We present a systematic survey of even-even nuclei with to identify where a very large prolate configuration driven by the second intruder orbit emerges. Within the energy density functional theory framework, we find in representative cases a pronounced prolate minimum at quadrupole deformation 0.3--0.4. A characteristic feature of these minima is a local enhancement of the hexadecapole () component relative to nearby deformations, which is a clear fingerprint of the -- coupling expected for the second intruder orbit. Representative comparisons among three Skyrme interactions show a similar appearance of the highly deformed minimum and a local enhancement of at the prolate minimum, indicating qualitative robustness with respect to the interaction. The resulting maps highlight specific heavy nuclei where highly deformed ground states are anticipated.

    nucl-thPRC(2025)·4 citations
  3. 03

    Proper derivation of subspace mapping from whole space mapping in boson expansion theory

    Kimikazu Taniguchi

    The norm operator method, which was recently proposed as a new formulation of the boson expansion theory (BET), is used to show that the subspace mapping is properly derived from the whole space mapping. This derivation requires the appropriate renormalization of the contribution of phonons that are not adopted as boson excitations in the subspace mapping. This was impossible with conventional BETs (which ignore these contributions), and is only made possible for the first time by the norm operator method, which treats these contributions appropriately. We also correct the confusion in the claims of conventional BETs. Namely, contrary to conventional claims, we show that when the phonon excitations not adopted as boson excitations make no contribution at all, the subspace mapping is obtained simply by discarding those excitations. Furthermore, we demonstrate that the Park operator, which had been considered effective only in the whole space mapping, is also effective in the subspace mapping. These findings provide a clear criterion for verifying the applicability of the boson expansion theory to large-amplitude collective motions and offer a new perspective on a microscopic foundation of the interacting boson model (IBM).

    nucl-thPTEP(2026)·0 citations
  4. 04

    A relativistic mechanism for the enhanced isovector spin-orbit interaction suggested by parity-violating electron scattering experiments

    Mengying Qiu🇨🇳 · Tong-Gang Yue🇨🇳 · Zhen Zhang🇨🇳 · Lie-Wen Chen🇨🇳

    Recent high-precision parity-violating electron scattering (PVES) measurements on Pb (PREX-II) and Ca (CREX) reveal a tension in their simultaneous description within modern nuclear energy density functionals (EDFs). Analyses of these data suggest that an enhanced isovector spin-orbit interaction may help account for both measurements, but its relativistic origin in covariant density functional theory remains to be clarified. We show that, within the framework of a covariant density-dependent point-coupling EDF, an enhanced isovector tensor coupling can naturally induce such a strong isovector spin-orbit interaction. This mechanism provides a promising route toward a simultaneous description of the PREX-II and CREX results while preserving a reasonable description of finite nuclei and nuclear matter. PVES on Ca thus provides a sensitive probe of the covariant isovector tensor interaction.

    nucl-thnucl-exPLB(2026)·4 citations
  5. 05

    Relativistic mean-field model with density- and isospin-density-dependent couplings

    Gabriel Frohaug🇺🇸 · Konstantin Maslov🇺🇸 · Veronica Dexheimer🇺🇸 · Joaquin Grefa🇺🇸 · Johannes Jahan🇺🇸 · Claudia Ratti🇺🇸 · Tulio E. Restrepo🇺🇸

    We present a new hadronic EoS with hyperons built within the relativistic mean-field (RMF) formalism with baryon-density- and isospin-density-dependent couplings. Motivated by microscopic calculations showing density- and isospin-asymmetry-dependence of self-energies, we implement a new form for the baryon-meson couplings. The parameters for the couplings are constrained by a Bayesian analysis, which anchors the model to nuclear saturation properties, chiral effective field theory (EFT) predictions for pure neutron matter, heavy-ion collision data, and HALQCD-based hyperon potential calculations at 3-momentum in both isospin-symmetric and pure neutron matter. The resulting EoS satisfies neutron star mass-radius constraints from NICER and GW170817, providing another way to address the hyperon puzzle. The low-density part of the EoS is described via nuclear statistical equilibrium with modern mass tables (AME20/FRDM12, 8244 nuclei), providing a novel and complete general-purpose EoS for astrophysical simulations.

    nucl-thastro-ph.HEhep-phPRD(2026)·5 citations
  6. 06

    Effects of short-range correlations at high densities on neutron stars with and without DM content: role of the repulsive self-interaction

    Odilon Lourenço🇪🇸 · Everson H. Rodrigues🇧🇷 · Carline Biesdorf🇪🇸 · Mariana Dutra🇪🇸

    In this work, we investigate how short-range correlations affect relativistic hadronic models at high densities, with direct consequences for the structure of neutron stars, both with and without dark matter content. Two versions of the model are examined: one with vector self-interactions up to second order () and another including a fourth-order term (). We show that SRC tend to soften the equation of state when only the quadratic term is present, but produce a noticeable stiffening once the term is included. The corresponding Tolman-Oppenheimer-Volkoff solutions for pure neutron stars indicate that short-range correlations reduce the maximum mass in the first case but increase it in the second. Extending the analysis to stars containing a fermionic dark matter component, within the two-fluid formalism, we verify that the same features appear in the respective mass-radius diagrams. In particular, the decrease of the maximum mass with increasing dark matter fraction is partly compensated by the SRC effects in the hadronic sector for the model with the fourth-order term. In all cases, the resulting parametrizations are consistent with recent astrophysical constraints, including the joint NICER-XMM-Newton analyses of the pulsars PSR J0030+0451 and PSR J0740+6620, as well as the gravitational-wave event GW190425.

    nucl-thhep-phPRD(2026)·2 citations

Affiliations

first authorsco-authorsvia INSPIRE