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Nuclear Theory·nucl-th

Monday·February 9, 2026

9 papers—4 primary·5 cross-listed

All9Primary4Cross-lists5
  1. 05

    [Submitted on 5 Feb 2026] (cross-list from hep-th)

    Holographic Charged Transport with Higher Derivatives

    Alex Buchel🇨🇦 · Sera Cremonini🇺🇸 · Mohammad Moezzi🇺🇸 · George Tringas🇺🇸

    We compute the first-order hydrodynamic transport coefficients (shear viscosity , bulk viscosity , and charge conductivity ) for a broad class of strongly coupled, four-dimensional charged relativistic gauge theory plasma with holographic gravitational duals containing higher-derivative corrections. The landscape of our holographic models captures non-conformal gauge theories with an arbitrary number of relevant coupling constants and a general scalar potential in the gravitational dual, allowing for a systematic exploration of charged transport along generic holographic RG flows. The leading-order higher-derivative corrections probe gauge theories with non-equal central charges at the ultraviolet fixed point, and enable the engineering of diverse temperature and charge density profiles for the viscosities and the conductivity. Our results establish the membrane paradigm in higher-derivative holographic models: all the transport coefficients are extracted from the black brane horizon values of the gravitational scalars, and various functions defining the gravitational holographic dual.

    Comments:
    48 pages, 1 figure
    Subjects:
    High Energy Physics — Theory (hep-th); Strongly Correlated Electrons (cond-mat.str-el); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2602.06144 [pdf]
    JHEP(2026)·3 citations
  2. 06

    [Submitted on 5 Feb 2026] (cross-list from astro-ph.HE)

    How Neutron Star Observations Point Towards Exotic Matter: Existing Explanations and a Prospective Proposal

    Mauro Mariani🇦🇷 · Ignacio F. Ranea-Sandoval🇦🇷

    Multi-messenger astronomical observations of neutron stars, together with more precise calculations and constraints coming from dense matter microphysics, are generating tension with regard to equations of state models used to describe neutron star cores. Assuming an abrupt first-order phase transition with a slow conversion speed between phases, we propose different slow stable hybrid star configurations aiming to reconcile all current constraints simultaneously; within this framework, we also introduce a novel non-CSS parametrization to the quark matter equation of state and discuss its strengths and limitations. We analyze our model results in conjunction with a review of other relevant theoretical possibilities existing in the literature. We found that modern neutron star observations seem to favor the existence of some type of exotic matter in the neutron star cores; in particular, our slow stable hybrid star scenario remains a proposal capable of satisfying these constraints. However, due both to the existing skepticism regarding some of the adopted hypotheses in most extreme neutron star measurements and to the precise adjustment needed for the equation-of-state parameters, significant tension and open questions remain.

    Comments:
    This article belongs to the Special Issue 'Microphysics Meets Astrophysics: Understanding Dense Matter Through Compact Objects' of the Symmetry journal
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
    arXiv:
    2602.06170 [pdf]
    Symmetry(2026)·3 citations
  3. 07

    [Submitted on 6 Feb 2026] (cross-list from nucl-ex)

    Quasi-elastic scattering for the nuclear ground state structure: An intriguing case of Si

    Y. K. Gupta🇮🇳 · B. Maheshwari🇫🇷 · G. K. Prajapati🇮🇳 · A. K. Jain · K. Hagino🇯🇵 · B. N. Joshi🇮🇳 · A. Pal🇮🇳 · N. Sirswal🇮🇳 · Pawan Singh🇮🇳 · S. Dubey🇮🇳 · V. V. Desai🇮🇳 · V. Ranga🇮🇳 and 8 other authors

    Quasi-elastic (QEL) scattering measurements have been performed using the Si projectiles off the Zr target at energies around the Coulomb barrier. Coupled-channels (CC) calculations were carried out in a large parameter space of quadrupole and hexadecapole deformations for the N=Z, Si and N=Z+2, Si nuclei. Si at the N=Z line is observed to be uniquely oblate shaped in its ground state. In contrast, for Si with just two additional neutrons -- oblate, prolate, and spherical CC descriptions are equally compatible with the measurements. To further investigate the nuclear structure evolution with varying neutron number, shell-model calculations were performed. These calculations reveal a sudden change in the nuclear structure aspects at Si in going from Si to Si. Combined reaction and structure analyses consistently indicate that Si does not possess a well-defined intrinsic shape, and it is a potential candidate for ``shape fluctuations" in its ground state.

    Subjects:
    Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2602.06580 [pdf]
    PLB(2026)·0 citations
  4. 08

    [Submitted on 6 Feb 2026] (cross-list from hep-ph)

    Physics of strong electromagnetic fields in relativistic heavy-ion collisions

    Koichi Hattori🇨🇳

    I discuss several roles of the strong electromagnetic fields created by relativistic heavy-ion collisions. These phenomena call for theoretical and experimental developments to understand dynamics of quark-gluon plasma (QGP) as well as purely electromagnetic processes in the ultraperipheral collisions.

    Comments:
    Contribution to the proceedings of ATHIC 2025
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2602.06697 [pdf]
    J.Subatomic Part.Cosmol.(2026)·0 citations
  5. 09

    [Submitted on 6 Feb 2026] (cross-list from physics.atom-ph)

    Proton-Size Resolution of the Hyperfine Puzzle in Hydrogen

    Gerald A. Miller

    Baym and Farrar (arXiv:2601.02300v1) have recently pointed out a puzzle in understanding the role of the hyperfine interaction in the ground state of a hydrogen atom. If one uses a variational wave function in which the Bohr radius, is replaced by a variational radius parameter, , first-order perturbation theory can give a contribution to the energy proportional to . This raises the question of why the hyperfine interaction does not lead to collapse of hydrogen. I show that including the effects of the non-zero size of the proton leads to a resolution of the puzzle such that the variational procedure yields a value of that is indistinguishable from .

    Comments:
    3 pages, 2 figures
    Subjects:
    Atomic Physics (physics.atom-ph); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2602.06929 [pdf]
    1 citation

Affiliations

first authorsco-authorsvia INSPIRE