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Nuclear Theory·nucl-th

Wednesday·May 27, 2026

12 papers—6 primary·6 cross-listed

All12Primary6Cross-lists6
  1. 01

    [Submitted on 25 May 2026]

    CNN-Based Online Trigger for QGP Event Selection

    Olga Soloveva🇩🇪 · Artemiy Belousov🇩🇪 · Ivan Kisel🇩🇪 · Elena Bratkovskaya🇩🇪

    Modern high-rate experiments require rare physics signatures to be identified in real time from continuous streams of reconstructed events under stringent data-throughput and storage constraints. We present a convolutional-neural-network-based trigger concept for selecting events associated with quark-gluon plasma (QGP) formation. Events are encoded as compact multidimensional histograms of reconstructed particle content, including particle species, momentum magnitude, and angular information. The method is first evaluated within the Parton-Hadron-String Dynamics (PHSD) framework, where microscopic QGP-related labels are available. As an independent validation, the same event representation and network architecture are applied to Ultra-relativistic Quantum Molecular Dynamics (UrQMD) simulations, providing a distinct description of the collision dynamics. Cross-checks between PHSD and UrQMD are used to assess the stability of the learned response against generator-dependent effects and to quantify model-transfer robustness. For realistic deployment, a lightweight C++ inference package, ANN4FLES, is employed at the physics-analysis stage after tracking and topology reconstruction. For Au+Au collisions at 30 AGeV, the classification accuracy decreases from 95.1% on generator-level PHSD events to 83.7% after full reconstruction, while retaining practical separation power for online event selection. SHAP-based interpretability analysis is used to identify the dominant particle-species contributions to the network decision.

    Comments:
    15 pages, 9 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2605.26280 [pdf]
    0 citations
  2. 02

    [Submitted on 26 May 2026]

    Spin-Dependent Nucleon-Nucleus Interactions Constrained by Neutron Observables and Their Impact on Near-Barrier Proton Fusion

    Kyoungsu Heo · Myung-Ki Cheoun · Kouichi Hagino

    We investigate the role of spin-dependent nucleon-nucleus interactions in nuclear reactions. To this end, we use neutron spin observables to constrain the dominant central spin-spin form factors and then apply the corresponding like-channel interactions to near-barrier fusion in the Nb system. The interactions are constructed within a folding framework based on a finite-range effective nucleon-nucleon force and organized in terms of radial form factors associated with their spin-spin, tensor, and spin-orbit components. Neutron spin observables in the Al, Co, and Nb target systems are analyzed within a distorted-wave Born approximation (DWBA) framework to constrain the sign and normalization in the central spin-spin parts of the radial form factors and to examine the assembled operator conventions. The calculation reproduces the observed sign systematics of the neutron spin observables for the three targets, indicating that the essential spin-dependent structure is properly incorporated. The unlike-channel (neutron-proton) interaction constrained by neutron scattering is then reconstructed for the corresponding like-channel (proton-proton) interaction and applied to a coupled-channels description of near-barrier fusion for the Nb system. The resultant spin-dependent interactions lead only to a weak modification of the effective barrier and change the fusion cross section by about - in the present calculation. These results show that the corresponding real spin-dependent correction in the like-channel is strongly suppressed in near-barrier fusion in . The present work thus connects the neutron-scattering constraints on the operator conventions with the fusion calculation in the proton channel, and quantifies the magnitude of the corresponding real spin-dependent correction in near-barrier fusion.

    Comments:
    16 pages, 6 figures, 5 tables
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2605.26561 [pdf]
    0 citations
  3. 03

    [Submitted on 26 May 2026]

    Cumulants of mean transverse momentum and elliptic flow in the hydrodynamic model of heavy-ion collisions

    Tribhuban Parida🇵🇱 · Piotr Bożek🇵🇱

    Higher order cumulants between the mean transverse momentum and elliptic flow are calculated in a relativistic viscous hydrodynamic model of relativistic heavy-ion collisions. The results of the hydrodynamic simulations are compared with calculations using event-by-event predictors of the final collective observables constructed from the initial state entropy distribution. The predictors describes quantitatively centrality dependence of the higher cumulants considered in the paper. We derive a quantitative relations between the cumulants of the mean transverse momentum and different moments of the harmonic flow. The hydrodynamic simulations satisfy those relation very well. Those relations could be used to test experimentally the collective origin of the observed correlations between the mean transverse momentum and harmonic flow.

    Comments:
    3 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    2605.26737 [pdf]
    1 citation
  4. 04

    [Submitted on 26 May 2026]

    Sensitivity of Heavy-Quark Dipolar Flow to its Initial Spatial Distributions in Cu+Au Collisions

    Ankit Kumar Panda · Tribhuban Parida

    We investigate charm-quark dynamics in asymmetric Cu+Au collisions at top RHIC energy using a Langevin approach embedded in a realistic hydrodynamic background. The intrinsic asymmetry of the colliding nuclei leads to a spatially lopsided initial energy-density profile, which generates a dipolar flow structure in the transverse plane even at midrapidity. As charm quarks propagate through this medium, they acquire a finite directed flow, . We find that the -integrated heavy-quark is approximately an order of magnitude larger than that of charged hadrons. In addition, the -differential exhibits strong sensitivity to the initial spatial distribution of heavy quarks, emphasizing the importance of pre-equilibrium dynamics in determining final-state anisotropies. Beyond geometric effects, also provides direct sensitivity to medium interactions through the temperature-dependent drag coefficient. Its pronounced dependence on this transport input indicates that precision measurements of heavy-flavor directed flow could place meaningful constraints on heavy-quark transport coefficients, thereby improving Langevin-based descriptions and predictive power for heavy-flavor observables in heavy-ion collisions.

    Comments:
    7 pages, 5 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    2605.26766 [pdf]
    0 citations
  5. 05

    [Submitted on 26 May 2026]

    Azimuthal asymmetry in exclusive quasi-elastic neutrino-nucleus interactions

    Marco Vanderpoorten🇧🇪 · Ashish Kumar Jha🇧🇪 · Mathias El Baz🇨🇭 · Kajetan Niewczas🇧🇪 · Federico Sanchez🇨🇭 · Natalie Jachowicz🇧🇪

    In neutrino oscillation experiments, exclusive measurements of neutrino-nucleus interactions play a critical role, by providing the theoretical and experimental input needed for a reliable estimation of the neutrino energy. In this paper, we derive the general form of the azimuthal angle distribution for quasi-elastic scattering, focusing on a dependency that has been routinely overlooked. We demonstrate that the outgoing nucleon exhibits a preference for emission outside the lepton scattering plane, with an asymmetric azimuthal distribution. In the context of neutrino-nucleus scattering, we argue that this asymmetry is caused by parity violation in the weak interaction. Furthermore, we show that in cross section calculations the asymmetry is sensitive to nuclear modeling choices and to the shell structure of the initial nucleus, thus providing a novel source of information for energy reconstruction in neutrino experiments. We study the experimental feasibility of observing this effect by applying a realistic momentum detection threshold and an intranuclear cascade. We estimate that the asymmetry is observable with () events at the 99% confidence level for neutrino interactions on C, suggesting that the effect is within reach of the current generation of neutrino detectors.

    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2605.26877 [pdf]
    0 citations
  6. 06

    [Submitted on 26 May 2026]

    Nuclear structure within the relativistic mean field approach including chiral symmetry and quark confinement effects

    M. Chamseddine🇫🇷 · J.-P. Ebran🇫🇷 · E. Khan🇫🇷 · B. K. Pradhan🇫🇷 · J. Margueron🇺🇸 · H. Hansen🇫🇷 · G. Chanfray🇫🇷

    The relativistic mean field approach, within a theoretical framework known as the chiral confining model incorporating chiral symmetry breaking and quark confinement effects, is applied for the first time to finite nuclei. Model parameters are calibrated through a Bayesian approach using nuclear empirical properties and doubly magic nuclei. The model provides a satisfactory description of binding energies and charge radii for medium and heavy nuclei, while larger discrepancies are observed in light nuclei. This behavior is linked to the constrained form of the chiral potential, which reduces flexibility away from saturation density. Charge radii are reproduced with very good accuracy, although density profiles remain slightly more diffuse than experimental ones. The extension to open-shell nuclei with a separable Gogny pairing interaction reveals enhanced pairing correlations associated with the large Dirac effective mass, reduced spin-orbit splittings, and increased single-particle level density around the Fermi surface. Finally, departures from the linear sigma model potential motivated by the Nambu-Jona-Lasinio framework are explored. Allowing additional flexibility in the chiral potential improves the description of light nuclei and reduces the Dirac mass, which in turn suppresses the anomalous pairing. These results highlight the sensitivity of finite nuclei properties to the structure of the chiral potential and the associated single-particle spectrum.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2605.26912 [pdf]
    1 citation

Affiliations

first authorsco-authorsvia INSPIRE