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Nuclear Theory·nucl-th

Monday·June 8, 2026

12 papers—6 primary·6 cross-listed

All12Primary6Cross-lists6
  1. 07

    [Submitted on 4 Jun 2026] (cross-list from physics.ins-det)

    Hyperon-Nucleon Spectrometer

    Xiaozhi Bai · Xu Cao · Zhe Cao · Jinhui Chen · Kai Chen · Qibo Chen · Shi Chen · Xin Chen · Yuquan Chen · Zhenyu Chen · Jianping Dai · Heng-Tong Ding and 228 other authors

    Chirality lies at the heart of low-energy QCD, governing the symmetry structure that shapes hadron masses and strong interaction dynamics. Among the most compelling open questions tied to chiral dynamics and spontaneous chiral symmetry breaking is the longstanding polarization puzzle, in which hyperons produced in unpolarized hadronic collisions exhibit a surprisingly large transverse polarization that remains theoretically unexplained. This whitepaper presents the proposal for the Hyperon-Nucleon Spectrometer (H-NS) at the High-Intensity heavy-ion Accelerator Facility (HIAF). Leveraging the high energy and high intensity of HIAF's proton and heavy-ion beams, the H-NS experiment will perform systematic studies of hyperon polarization phenomena and their underlying mechanisms in proton-proton (), proton-nucleus (), and nucleus-nucleus () collisions in the fixed target mode. A wide-range beam energy scan, including proton beams from 3 GeV up to 9.3 GeV (HIAF) and up to 32 GeV (upgraded HIAF), will be conducted to examine the dependence of polarization on collision energy. The spectrometer is designed with specialized detectors capable of high-precision reconstruction of final-state baryon polarizations. Among its many interesting and important measurements, H-NS will simultaneously measure hyperon and proton spin observables to explore the polarization mechanism in hadronic interactions and the spin structure of baryons. Furthermore, the use of and collisions will enable detailed investigations of cold and hot nuclear matter effects on spin polarization. Its physics program and detector development will significantly benefit the future Electron-ion Collider in China.

    Comments:
    69 pages, Hyperon-Nucleon Spectrometer (H-NS) white paper
    Subjects:
    Instrumentation and Detectors (physics.ins-det); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2606.06553 [pdf]
    2 citations
  2. 08

    [Submitted on 4 Jun 2026] (cross-list from gr-qc)

    Radial Oscillations of Viscous Stars at Finite Temperature

    Amanda Guerrieri🇧🇷 · Gabriel S. Rocha🇧🇷 · Gabriel S. Denicol🇧🇷 · Raissa F. P. Mendes🇧🇷

    We study the radial oscillation spectrum of relativistic stars within Israel-Stewart and Navier-Stokes theories, extending previous analyses to include heat diffusion and a thermodynamically consistent finite-temperature equation of state. The inclusion of heat flux gives rise to a distinct thermal sector in the mode spectrum, whose structure closely mirrors the dispersion relations of an infinite dissipative fluid. Within Israel-Stewart theory, the thermal modes transition from purely damped to propagating behavior above a critical overtone number, providing a finite-size realization of relativistic second sound in compact stars. Remarkably, the finite stellar geometry can push even the fundamental thermal mode into the propagating regime -- a feature with no continuum analogue. For the class of equations of state considered here, where finite-temperature corrections enter as controlled, Sommerfeld-type perturbations of a cold polytrope, the thermal sector couples only weakly to the ordinary fluid oscillation spectrum, with the coupling being of second order in a suitable temperature parameter. We further show that the discrete stellar spectrum is well captured by an analytic ansatz constructed from the flat-spacetime dispersion relations, with the star's finite radius discretizing the continuous mode structure. Our results complete the analysis of radial oscillations of viscous stars by incorporating the last remaining dissipative degree of freedom within the Israel-Stewart framework.

    Comments:
    14 pages, 6 figures
    Subjects:
    General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
    arXiv:
    2606.06600 [pdf]
    1 citation
  3. 09

    [Submitted on 4 Jun 2026] (cross-list from hep-ph)

    Lepton interactions from GeV to EeV

    Reinaldo Francener🇧🇷

    In this work, we investigate the phenomenological consequences of neutrino and muon interactions with matter. In our studies, we focused in phenomenological predictions for two experiments: FASER and IceCube. FASER is a detector located at the LHC that measures neutrinos produced in proton-proton collisions. A new version of FASER, FASER2, has been proposed to operate in the Forward Physics Facility during the high-luminosity regime of the LHC. The intense flux of tau neutrinos expected at FASER2 motivated us to study the polarization effects of the tau produced in charged current interactions. Our results show that the produced taus will not be completely polarized. Among the Standard Model particles, only neutrinos and muons produced in proton-proton collisions at the LHC can reach FASER. In our study, we show that muon-initiated events can reveal interesting nucleon properties, such as nuclear effects and the existence of an intrinsic charm. The high number of events induced by neutrinos at FASER motivated us to study rare processes in neutrino interaction, such as the neutrino trident. Our results indicate that the neutrino trident process can be observed at FASER2. We have also studied muon trident at the LHC, and we showed that tau pair production can be observed for the first time in this reaction. In contrast to neutrinos detected at the LHC, the neutrinos observed at IceCube come from natural sources, being mainly atmospheric and astrophysical neutrinos. IceCube is capable of observing neutrinos across a wide energy spectrum, ranging from a few GeV to beyond PeV. We show that the study of these events can contribute to our understanding of the structure of target hadrons, as well as the search for physics effects beyond the Standard Model in the propagation of these neutrinos in the universe until they reach the Earth.

    Comments:
    PhD thesis
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
    arXiv:
    2606.06773 [pdf]
    0 citations
  4. 10

    [Submitted on 5 Jun 2026] (cross-list from cs.LG)

    Product units in gated recurrent units improve nuclear-mass prediction

    Ziyuan Li · Paulo S.A. Freitas · John W. Clark · Babette Dellen

    The prediction of masses of atomic nuclei using machine learning can complement theoretical models and advance the exploration of poorly known domains of the nuclear chart. We propose a machine learning technique based on gated recurrent units (GRU), which have demonstrated competitive performance in nuclear-mass prediction by exploiting long-term dependencies. By integrating multiplicative interactions and product-unit transformations within recurrent units, we report significant improvements in nuclear-mass prediction. Computations are performed in the complex domain to jointly capture amplitude and phase dynamics. For interpolation and temporal-extrapolation tasks based on the atomic mass evaluation (AME2016 and AME2020), the complex additive-multiplicative product-unit gated recurrent unit (AM-PU-GRU) model consistently achieves the lowest prediction errors, with an interpolation RMSE of 0.227 0.004 MeV and an extrapolation RMSE of 0.179 0.015 MeV. These results surpass other state-of-the-art machine learning models and also outperform the real-valued GRU baseline and product-unit ablation variants, while remaining robust to different theoretical priors, including WS4 and SEMF. Our findings establish complex-valued product-unit recurrent networks as a new benchmark for sequence-based nuclear-mass prediction.

    Comments:
    Accepted at ICCS 2026
    Subjects:
    Machine Learning (cs.LG); Nuclear Theory (nucl-th)
    arXiv:
    2606.06866 [pdf]
    In: Lecture Notes in Computer Science, Sp…·0 citations
  5. 11

    [Submitted on 5 Jun 2026] (cross-list from nucl-ex)

    Measurement of energy-level splitting from Charge-Symmetry Breaking in = 4 mirror hypernuclei

    STAR Collaboration

    Breaking of fundamental symmetries is a ubiquitous phenomenon in physics, underlying the origin of mass and the emerging structure in the universe. The charge symmetry of hyperon-nucleon interactions can be probed through the difference in the binding energy () between mirror hypernuclei. In this paper, the of mirror hypernuclei with atomic mass number = 4, and , are measured in Au+Au collisions at the center-of-mass energy of = 3 GeV with the STAR experiment at RHIC. For the ground states, we obtain () = 2.24 0.02 (stat.) 0.04 (syst.) MeV and () = 2.39 0.05 (stat.) 0.05 (syst.) MeV, yielding a charge-symmetry breaking (CSB) effect at the level of 0.15 0.05 (stat.) 0.04 (syst.) MeV. In combination with previous measurements of -ray transitions from their excited states, the CSB in excited states is determined to be 0.17 0.05 (stat.) 0.04 (syst.) MeV. These measurements provide a precise determination of CSB in the hypernuclear system, and establish that the binding energy differences in ground and excited states are comparable in magnitude but opposite in sign, offering new insight to the CSB effect in -nucleon interactions.

    Comments:
    13 pages, 6 figures
    Subjects:
    Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2606.06873 [pdf]
    1 citation
  6. 12

    [Submitted on 5 Jun 2026] (cross-list from hep-ph)

    Mechanical distribution of the pseudoscalar charmonium and bottomonium on the light-front

    Ashutosh Dwibedi🇮🇳 · Satyajit Puhan🇹🇼 · Sabyasachi Ghosh🇮🇳

    We investigate the energy-momentum tensor of pseudoscalar charmonium and bottomonium within the framework of the light-front quark model. The gravitational form factors (GFFs), namely the and -terms, are evaluated in terms of the light-front wave functions. The corresponding spatial mechanical distributions in the transverse plane are obtained through the Fourier transform of these GFFs. To examine the sensitivity of the results to the internal quark-antiquark distribution inside the meson, two distinct Gaussian forms are employed for the spatial part of the wave function. We analyze several mechanical properties in the transverse plane, including the momentum density, pressure distribution, shear stress, force density, and internal energy density. The pressure distribution exhibits a node where it changes sign from positive (repulsive) to negative (attractive) with increasing transverse distance. The force distribution remains positive throughout the transverse plane, supporting the stability condition proposed in earlier studies. Most of the spatial distributions, except for the shear stress, are found to be sensitive to the choice of the spatial wave function near the center of the meson, while they become nearly insensitive toward the periphery. In contrast, the shear stress distribution exhibits noticeable sensitivity to the choice of wave function in the intermediate transverse region.

    Comments:
    comments are welcome!
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2606.07073 [pdf]
    3 citations

Affiliations

first authorsco-authorsvia INSPIRE