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Nuclear Theory·nucl-th

Wednesday·August 26, 2026

11 papers—4 primary·7 cross-listed

All11Primary4Cross-lists7
  1. 01

    [Submitted on 24 Aug 2026]

    Deuterium Production in an Effective Field Theory Constructed from On-Shell Amplitudes

    Tim M.P. Tait🇺🇸

    We compute the deuterium-production reaction in an effective field theory whose degrees of freedom are the nuclear states themselves: the amplitude is assembled from on-shell three-point vertices, glued across its factorization channels, and completed by the contact terms consistent with the symmetries. The deuteron enters through the -- vertex, normalized to the measured asymptotic normalization coefficient. Rescattering of the nucleon pair is resummed dispersively, leaving two short-distance constants, an isovector magnetic and an electric dipole contact interaction. A joint Bayesian fit to the thermal capture measurements and the SLEGS photodisintegration data finds both of natural size and determines the thermonuclear rate to 0.22-0.24% across the nucleosynthesis window, including systematics spanning the defensible treatments of the SLEGS data and of the -wave rescattering. Truncating the expansion is bounded separately at 0.12%, of which the next order of contact terms -- degenerate with the two fitted constants -- supplies 0.03%, for a total theory uncertainty of 0.25-0.27%. Propagated through a BBN network, the rate shifts the predicted primordial deuterium by -0.06% and cuts this reaction's contribution to the D/H uncertainty from 0.089% to 0.050%, retiring it from the primordial D/H error budget for practical purposes.

    Comments:
    20 pages, 8 figures; companion to arXiv:2607.05514; ancillary file anc/npdg_rate_table.csv tabulates the thermonuclear rate with its total theory uncertainty on the PRIMAT temperature grid
    Subjects:
    Nuclear Theory (nucl-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th)
    arXiv:
    2608.23699 [pdf]
    0 citations
  2. 02

    [Submitted on 24 Aug 2026]

    Deformed self-consistent Green's function method for atomic nuclei at second and third order in the algebraic diagrammatic construction

    A. Scalesi · T. Duguet · V. Somà

    The description of atomic nuclei from first principles constitutes one of the central goals of nuclear theory. Polynomial-scaling expansion methods have extended \textit{ab initio} calculations at sub-percent accuracy to medium-mass nuclei and a few closed-shell heavy nuclei, but deformed doubly open-shell heavy and superheavy nuclei remain out of reach. The self-consistent Green's function (SCGF) formalism is here extended to doubly open-shell nuclei by allowing the one-body propagator to spontaneously break SU(2) rotational symmetry. The resulting deformed SCGF (dSCGF) scheme, based on the algebraic diagrammatic construction truncated at first, second, and third order, is implemented in a newly developed many-body suite, \texttt{FoxTrot}. Numerical strategies required to handle the associated, symmetry-unrestricted -scheme working basis are discussed in detail. The method is illustrated through a study of Si based on the 1.8/2.0 (EM) Hamiltonian. The impact of the three-nucleon interaction and of its rank-reduction approximation on the deformed Hartree-Fock total energy curve is examined, and the correlated curve obtained from constrained dSCGF calculations is shown to differ appreciably from the mean-field one. Physical solutions appearing as minima of the correlated curve are shown to be reachable via unconstrained calculations starting from any point along the deformed Hartree-Fock curve, demonstrating the self-consistent character of the method. The Si ground-state binding energy at third order, extrapolated to the infinite basis-size limit, reproduces experiment within , while the excited prolate solution is consistent with the observed shape isomer. The present developments open the way to an accurate ab initio description of all (very) heavy nuclei in the near future.

    Comments:
    14 pages, 7 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2608.23700 [pdf]
    1 citation
  3. 03

    [Submitted on 25 Aug 2026]

    Self-Consistent Determination of the Transition Temperature Between the and Reactions

    R. Ya. Kezerashvili · N. A. Burkova · A. S. Tkachenko · S. B. Dubovichenko

    We present the first self-consistent theoretical study of the competing and reactions within the same modified potential cluster model (MPCM). For the CN reaction, total cross sections, astrophysical factors, and reaction rates are calculated using interaction potentials constrained by the available scattering and bound-state data. The astrophysical -factor is estimated as ~keV. Combining these results with our recent MPCM calculations for , we determine the transition temperature at which proton capture overtakes neutron capture in the production of . The self-consistent comparison predicts a transition temperature under Maxwell--Boltzmann statistics, significantly higher than previous estimates. The analysis is extended to Tsallis statistics, demonstrating that deviations from thermal equilibrium produce substantial shifts of the transition temperature. These results provide improved nuclear-physics input for astrophysical nucleosynthesis calculations.

    Comments:
    7 pages, 5 figures
    Subjects:
    Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR)
    arXiv:
    2608.24318 [pdf]
    0 citations
  4. 04

    [Submitted on 25 Aug 2026]

    Resolving the -meson directed-flow puzzle by multi-step meson--baryon dynamics

    Yingjie Zhou🇩🇪 · Taesoo Song🇩🇪 · Susanne Glässel🇩🇪 · Jiaxing Zhao🇩🇪 · Christoph Blume🇩🇪 · Iouri Vassiliev🇩🇪 · Vadim Voronyuk🇷🇺 · Yaping Wang🇨🇳 · Nu Xu🇨🇳 · Jörg Aichelin🇫🇷 · Elena Bratkovskaya🇩🇪

    Recent STAR measurements at fixed-target Beam Energy Scan energies have revealed an unexpectedly large directed flow of mesons in Au+Au collisions, comparable to that of protons and baryons and much stronger than that of light strange mesons. Since the is a hidden-strangeness meson with relatively weak interactions with non-strange hadrons, this observation has been interpreted as a possible signal of unconventional baryonic dynamics or exotic baryonic resonances coupled to the channel. Within the framework of the Parton-Hadron-Quantum-Molecular-Dynamics(PHQMD) model, we demonstrate that in the high baryon density region, mesons are produced predominantly through multi-step meson--baryon and meson--hyperon reactions, whose transition amplitudes are constrained by a coupled-channel -matrix calculation based on an extended SU(6) chiral effective Lagrangian. Together with the in-medium broadening of the spectral function, these baryon-driven production channels enhance near-threshold production and imprint the collective motion of the baryon-rich source on the produced mesons.

    Comments:
    4 pages, 3 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2608.24573 [pdf]
    0 citations

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first authorsco-authorsvia INSPIRE