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Nuclear Theory·nucl-th

Tuesday·February 3, 2026

18 papers—15 primary·3 cross-listed

All18Primary15Cross-lists3
  1. 16

    [Submitted on 2 Feb 2026] (cross-list from hep-ph)

    Fully strange tetra- and penta-quarks in a chiral quark model

    Gang Yang🇨🇳 · Jialun Ping🇨🇳 · Jorge Segovia🇪🇸

    Motivated by the recently reported resonant structure , a strong candidate for a fully strange tetraquark with positive parity, we perform a systematic study of fully strange tetra- and penta-quark systems within a chiral quark model. Low-lying -wave configurations of the and systems are investigated using the Gaussian Expansion Method (GEM) combined with the Complex Scaling Method (CSM), which allows for a unified treatment of bound, resonant, and scattering states. For tetraquarks, all possible configurations: meson-meson, diquark-antidiquark, and K-type structures, with complete color bases, are incorporated, while baryon-meson and diquark-diquark-antiquark configurations are considered for pentaquarks. Several weakly bound states and narrow resonances are identified in both sectors. In particular, a compact fully strange tetraquark with is found near , providing a natural interpretation of the resonance. Additional exotic states with dominant hidden-color and K-type components are predicted in the mass ranges GeV for tetraquarks and GeV for pentaquarks. The internal structure of these states is analyzed through their sizes, magnetic moments, and wave-function compositions, highlighting the essential role of channel coupling and exotic color configurations. Finally, promising two-body strong decay channels are proposed to facilitate future experimental searches.

    Comments:
    17 pages, 7 figures, 16 tables
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2602.01759 [pdf]
    PRD(2026)·0 citations
  2. 17

    [Submitted on 2 Feb 2026] (cross-list from hep-ph)

    Systematical decomposition of dimension-11 short-range neutrinoless double beta decay operators

    Shi-Yu Li🇨🇳 · Gui-Jun Ding🇨🇳

    Neutrinoless double beta decay () may receive sizable contributions from short-range physics beyond the Standard Model. We present a systematical classification of all tree-level ultraviolet completions of the dimension-11 short-range decay operators, renormalizable scenarios with scalar and fermion mediators are considered. We identify eight distinct topologies and twenty-eight viable diagrams, from which all consistent UV completions are generated by imposing Standard Model gauge invariance. All these models involve a total of 61 new fields beyond the Standard Model and they typically feature fractionally charged fermions and exotic bosons such as dileptons, diquarks, and leptoquarks. We further study a representative model without colored mediators and analyze its implications for the decay half-life and light neutrino masses. We find that current and future decay experiments impose stringent constraints. Our systematic decomposition provides a general framework for exploring exotic short-range contributions to decay in future experiments.

    Comments:
    39 pages, 13 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
    arXiv:
    2602.02152 [pdf]
    JHEP(2026)·1 citation
  3. 18

    [Submitted on 2 Feb 2026] (cross-list from hep-lat)

    Wilson loops with neural networks

    Verena Bellscheidt🇺🇸 · Nora Brambilla🇩🇪 · Andreas S. Kronfeld🇩🇪 · Julian Mayer-Steudte🇩🇪

    Wilson loops are essential objects in QCD and have been pivotal in scale setting and demonstrating confinement. Various generalizations are crucial for computations needed in effective field theories. In lattice gauge theory, Wilson loop calculations face challenges, including excited-state contamination at short times and the signal-to-noise ratio issue at longer times. To address these problems, we develop a new method by using neural networks to parametrize interpolators for the static quark-antiquark pair. We construct gauge-equivariant layers for the network and train it to find the ground state of the system. The trained network itself is then treated as our new observable for the inference. Our results demonstrate a significant improvement in the signal compared to traditional Wilson loops, performing as well as Coulomb-gauge Wilson-line correlators while maintaining gauge invariance. Additionally, we present an example where the optimized ground state is used to measure the static force directly, as well as another example combining this method with the multilevel algorithm. Finally, we extend the formalism to find excited-state interpolators for static quark-antiquark systems. To our knowledge, this work is the first study of neural networks with a physically motivated loss function for Wilson loops.

    Comments:
    23 pages, 17 figures Updated to match the published version
    Subjects:
    High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2602.02436 [pdf]
    PRD(2026)·2 citations

Affiliations

first authorsco-authorsvia INSPIRE