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Nuclear Theory·nucl-th

Friday·May 22, 2026

6 papers—4 primary·2 cross-listed

All6Primary4Cross-lists2
  1. 05

    [Submitted on 21 May 2026] (cross-list from hep-ph)

    Equation of State at High Baryon Densities from a Thermodynamically Informed Neural Network

    Musfer Adzhymambetov🇺🇦

    We present a four-dimensional equation of state for strongly interacting matter at finite temperature and conserved charge densities, constructed using a deep neural network. It is designed for direct use in hybrid models of relativistic heavy-ion collisions: it reproduces hadron resonance gas thermodynamics at typical particlization scales, is consistent with lattice QCD at low baryon chemical potential, and extrapolates into the high-density region inaccessible to either approach, which is precisely the regime targeted by RHIC BES, FAIR, HADES, and CBM. Thermodynamic consistency throughout the full phase space is enforced via a physics-informed loss function. We demonstrate the developed equation of state by implementing it at zero net strangeness and fixed electric-to-baryon charge ratio within the integrated hydrokinetic model.

    Comments:
    Second version. 9 pages, 5 figures. Added link to ready-to-use EoS tables for hydrodynamic simulations. The reader is encouraged to test the equation of state in their hydrodynamic codes and to reach out if help with implementation is needed
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2605.22199 [pdf]
    0 citations
  2. 06

    [Submitted on 21 May 2026] (cross-list from physics.atom-ph)

    Shielded inner-shell transitions in atomic samarium for tests of fundamental physics

    R. Aramyan🇩🇪 · D. Budker🇩🇪 · V. A. Dzuba🇦🇺 · V. V. Flambaum🇦🇺 · S. G. Porsev🇺🇸 · M. S. Safronova🇺🇸 · O. Tretiak🇩🇪 · K. Zhang🇩🇪

    Forbidden atomic transitions provide some of the most stringent low-energy tests of physics beyond the Standard Model, with sensitivity set by the interplay between the sought-for signals and systematics suppressed by symmetry. Here we identify the previously unobserved D level of neutral samarium at , opening the FD inner-shell transition for precision spectroscopy. Candidate lines extracted from dual-comb absorption spectra were assigned using double-resonance population-depletion and sequential-excitation measurements. The observed pressure broadening, , and pressure shift, , indicate an inner-shell -transition shielded from external perturbations. Many-body calculations predict a metastable lifetime (quality factor ), large sensitivity coefficients for variation of the fine-structure constant, and a nuclear-spin-dependent parity-violation amplitude comparable to that of cesium. Crucially, the selection rule suppresses by symmetry both the nuclear-spin-independent parity-violation channel and the M1 and E2 backgrounds that complicated previous heavy-atom experiments, yielding a uniquely clean window onto the nuclear anapole moment. The two stable spin- isotopes of samarium provide a remarkable opportunity to largely cancel atomic-structure uncertainties by measuring the ratio of parity-violation effects in the two isotopes. These results establish neutral samarium as a platform for inner-shell precision spectroscopy and tests of physics beyond the Standard Model.

    Subjects:
    Atomic Physics (physics.atom-ph); Nuclear Theory (nucl-th); physics.optics (physics.optics); Quantum Physics (quant-ph)
    arXiv:
    2605.22318 [pdf]
    0 citations

Affiliations

first authorsco-authorsvia INSPIRE