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Nuclear Theory·nucl-th

Wednesday·December 10, 2025

10 papers—4 primary·6 cross-listed

All10Primary4Cross-lists6
  1. 01

    Rapidly Spinning Massive Pulsars as an Indicator of Quark Deconfinement

    Christoph Gärtlein🇵🇹 · Violetta Sagun🇬🇧 · Oleksii Ivanytskyi🇵🇱 · David Blaschke🇵🇱 · Ilídio Lopes🇵🇹

    We study rotating hybrid stars, with particular emphasis on the effect of spin on the deconfinement phase transition and star properties. Our analysis is based on a hybrid equation of state with a phase transition from hadronic matter containing hyperons to color-superconducting quark matter, where the quark phase is modeled within a relativistic density functional approach. By varying the strength of the vector repulsion and diquark pairing couplings in the microscopic quark Lagrangian, we construct a set of hybrid star sequences with different quark-matter onset densities. This framework ensures consistency with astrophysical and gravitational wave constraints on mass, radius, and tidal deformability.

    nucl-thastro-ph.HEhep-phJ.Subatomic Part.Cosmol.(2026)·3 citations
  2. 02

    Wavefunction-Based Emulation of Coupled-Channels Scattering with Non-Affinely Parametrized Interactions

    M. Catacora-Rios · Kyle Beyer · Pablo Giuliani · Kyle Godbey · Richard J. Furnstahl · Filomena Nunes

    Physics based emulators offer a fast and reliable replacement for an exact solution of the scattering problem in nuclear physics. Previous work developed a reduced-basis emulator for single-channel elastic scattering using an optical potential. Since many reactions of interest can be cast as a coupled-channel problem, the purpose of this work is to extend the RBM to a coupled-channel framework (CC-RBM). Although the framework derived is general, in this work we apply it to reactions where the Hamiltonian coupling term comes from assuming a rotational structure model for the target. From a set of training coupled-channel wavefunctions, we perform a singular value decomposition to obtain a reduced set of basis wavefunctions, and then solve the extended (Petrov-)Galerkin equations. In addition, the empirical interpolation method is used to expand the potentials. We apply the CC-RBM method to elastic and inelastic scattering of neutrons on 48Ca including a quadrupole coupling to populate the first 2+ state, and neutrons on 208Pb, including an octupole coupling to populate its first 3- state. We demonstrate that the CC-RBM calculated cross sections match those obtained using traditional finite-difference methods. We show that the CC-RBM results can reliably reproduce the nuclear scattering cross sections at different energy regimes. The computational accuracy versus time plots demonstrate that the CC-RBM method efficiently increases precision with increasing basis size. Most importantly, for the precisions required in reaction calculations (a percent on the cross section), we find the CC-RBM method offers roughly one and a half orders of magnitude gain in computational speed compared to the traditional coupled-channels solver. However, we also discuss how this scaling becomes less favorable, the larger the number of channels included in the coupled-channel set.

    nucl-thPRC(2026)·9 citations
  3. 03

    The QCD phase diagram

    Szabolcs Borsanyi · Paolo Parotto🇮🇹

    Strongly interacting matter exhibits new phases under extreme conditions. Matter was exposed to such extremes not only in the Early Universe, but also today in the cores of neutron stars, as well as in laboratory experiments at a much smaller scale. We study the underlying theory, Quantum Chromodynamics (QCD) with the methods of statistical physics and explore the various phases we may encounter in experiment, such as the Quark Gluon Plasma. We briefly summarize the experimental evidence for the new forms of matter and review the theoretical efforts to embed these findings in the broader context of quantum field theory, with special attention to exact and broken symmetries and critical behaviour.

    nucl-thhep-lat15 citations
  4. 04

    A Bayesian Approach Study of Hybrid Neutron Stars

    Fábio Köpp🇺🇸 · César H. Lenzi🇺🇸 · César V. Flores🇺🇸 · Débora P. Menezes🇺🇸

    In this work, we explore how astronomical observations (specifically measurements of masses, radii, and tidal deformabilities) can constrain the presence of quark matter inside neutron stars, namely the phase transition from nuclear matter to deconfined quark matter. Our approach employs Bayesian analysis to study this phenomenon. Hadronic matter is modeled using the relativistic mean-field (RMF) approximation, for which we have selected two parameter sets: \(NL3^{*}\omega\rho\), representing hadronic matter with nucleons only, and with nucleons only and , which includes hyperons. On the other hand deconfined quark matter is modeled using the vector-MIT bag model. For our purpose, the phase transition is implemented using the Maxwell construction. Bayesian inference is performed by tuning three parameters: the bag constant (i.e. ), the vector coupling constant \(\left(G_{v}\right)\), and the Dirac sea contribution (). We found that a phase transition could exist at densities below \(2.0\,n_{0}\) for both the and parametrizations. As a consequence, our results also indicate that a hybrid neutron star could have a large quark core that comprises more than \(80\%\) of its size.

    nucl-thastro-ph.HEPRD(2026)·0 citations

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