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Nuclear Theory·nucl-th

Monday·February 16, 2026

11 papers—6 primary·5 cross-listed

All11Primary6Cross-lists5
  1. 07

    [Submitted on 12 Feb 2026] (cross-list from astro-ph.HE)

    First-Principles Polar-Cap Currents in Multipolar Pulsar Magnetospheres

    Chun Huang

    X-ray pulse-profile modeling of millisecond pulsars offers a direct route to measuring neutron star masses and radii, thereby constraining the dense-matter equation of state. However, standard analyses typically rely on \emph{ad hoc} hotspot parameterizations rather than self-consistent physical models. While connecting surface heating directly to the magnetospheric geometry provides a more natural physical pathway, computing global magnetospheric solutions is too computationally expensive to perform on-the-fly during parameter inference. In this work, we bridge this gap by deriving fully analytic, first-principles expressions for surface return currents in mixed dipole--quadrupole magnetospheres. Working within force-free electrodynamics, we generalize the field-aligned current invariant , the crucial scalar that maps the far-zone magnetic structure to the near-zone heating rate, from the standard dipole approximation to arbitrary quadrupolar configurations. We demonstrate that even when the quadrupole component is sub-dominant in the far zone (the mixing regime), using a dipole-based heating prescription fails to capture the significant enhancement or suppression of the return-current density on the polar cap. Our consistent quadrupole-aware framework reveals that these multipolar currents redistribute the surface heating, leading to systematic discrepancies in predicted pulse profiles that are amplified by atmosphere beaming and can reach near pulse peaks. These results provide a rigorous analytic foundation for mapping global magnetic geometry to surface heating in multipolar magnetospheres, enabling physically consistent inference beyond the idealized dipole approximation.

    Comments:
    23 pages, 6 figures, Accepted publication in ApJ
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
    arXiv:
    2602.12376 [pdf]
    ApJ(2026)·1 citation
  2. 08

    [Submitted on 12 Feb 2026] (cross-list from astro-ph.HE)

    Correlated and uncorrelated Monte Carlo neutron capture rate variations in weak -process simulations

    Atul Kedia · Jeffrey M. Berryman · Jonathan Cabrera Garcia · Jutta E. Escher · Oliver C. Gorton · Erika M. Holmbeck · Gail C. McLaughlin · Cole D. Pruitt · Andre Sieverding · Rebecca Surman

    Reliable predictions of weak rapid neutron capture (-process) abundances require a systematic treatment of nuclear physics uncertainties, especially neutron capture rates far from stability. We employ new neutron capture rates from cross sections calculated with Yet Another Hauser-Feshbach Code () using an uncertainty-quantified Koning-Delaroche potential modified for use on neutron-rich systems. Using these rates as a baseline, we perform Monte-Carlo studies with independent rate variations (uncorrelated Monte Carlo) and find correlations between specific neutron capture rates and the resulting elemental abundances for the three weak r-process scenarios: two separate simulations of neutron star merger remnant accretion disks and a simulation of a magnetorotational supernova. We discuss the underlying nuclear dynamics that give rise to these correlations and the role of astrophysical conditions in them. We demonstrate how reducing the uncertainty in these rates would improve the prospects for conducting precision -process studies in the future. We additionally present a correlated Monte Carlo study, which incorporates the full covariance matrix that describes the relationships between individual neutron capture rates that arise from an uncertainty-quantified optical potential. We find that the magnitude of the uncertainty in the abundance pattern is similar to that produced by an uncorrelated Monte Carlo that employs only the on-diagonal components of the covariance matrix. We show how correlations restructure how the abundances co-vary, but do not necessarily decrease the overall uncertainty envelope.

    Comments:
    21 pages, 13 figures
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
    arXiv:
    2602.12428 [pdf]
    2 citations
  3. 09

    [Submitted on 13 Feb 2026] (cross-list from hep-ph)

    NNLL resummation of azimuthal decorrelation for boosted top quark pair production at the LHC

    Qian-Shun Dai🇨🇳 · Ming-Jun Liu🇨🇳 · Ding Yu Shao🇨🇳

    The precision program of the Large Hadron Collider (LHC) increasingly relies on the boosted regime, where top quark properties are probed at the TeV scale. However, the simultaneous presence of heavy quark mass effects and large logarithmic corrections from soft radiation poses a significant challenge for theoretical predictions. In this work, we develop a transverse momentum dependent (TMD) factorization and resummation framework for boosted top quark pair production in the back-to-back limit at the LHC. By employing a two step matching procedure, matching QCD through onto , we systematically resum large logarithms associated with both the top quark mass and the azimuthal decorrelation. A key component of our formalism is the first extraction of the two-loop ultra-collinear function, obtained via the refactorization of the fully differential massive soft function. This result completes the set of perturbative ingredients required to achieve accuracy for the azimuthal decorrelation distribution. Our framework establishes a new benchmark for heavy-quark TMD resummation in the boosted limit at hadron colliders.

    Comments:
    29 pages, 2 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2602.12572 [pdf]
    JHEP(2026)·1 citation
  4. 10

    [Submitted on 13 Feb 2026] (cross-list from hep-ph)

    Meson Form Factors

    Johan Bijnens (Lund)🇸🇪

    We give an introduction to and a short overview of light meson form factors. We first discuss the classical picture and how it then fits in with amplitudes in quantum field theory. We give a short overview of the main theoretical methods and then discuss pion, kaon, eta and eta' form factors.

    Comments:
    8 pages, article for the Encyclopedia of Particle Physics
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2602.12715 [pdf]
    0 citations
  5. 11

    [Submitted on 13 Feb 2026] (cross-list from hep-ph)

    Rotating synchrotron radiation: Photon emission from magnetized and rotating quark-gluon plasma

    Matteo Buzzegoli🇷🇴 · Sergiu Busuioc🇷🇴 · Jonathan D. Kroth🇺🇸 · Nandagopal Vijayakumar🇺🇸 · Kirill Tuchin🇺🇸

    This paper investigates the production of non-prompt photons originating from rotating synchrotron radiation (RoSyRa), specifically the emission of photons by a rigidly rotating quark-gluon plasma in thermal equilibrium, in the presence of an external magnetic field. We compute the non-prompt photon spectrum and its elliptic flow () at mid-rapidity. In particular, we investigate the finite volume effects. We find that at low transverse momentum, the magnetic field induces a significant , while the plasma rotation boosts the synchrotron radiation of negatively charged quarks. These findings make RoSyRa a viable candidate mechanism to resolve the "direct photon puzzle."

    Comments:
    25 pages, 17 figures. v2: published version
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    2602.13044 [pdf]
    PRD(2026)·3 citations

Affiliations

first authorsco-authorsvia INSPIRE