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Nuclear Theory·nucl-th

Thursday·September 25, 2025

8 papers—1 primary·7 cross-listed

All8Primary1Cross-lists7
  1. 02

    [Submitted on 23 Sept 2025] (cross-list from hep-ph)

    Bayesian Constraints on Pre-Equilibrium Jet Quenching and Predictions for Oxygen Collisions

    Daniel Pablos🇪🇸 · Adam Takacs🇩🇪

    The contrast between the as-yet unmeasurable energy-loss effects in proton-nucleus collisions and the striking magnitude of the so-called high-momentum flow coefficients challenges our understanding of jet quenching mechanisms in large nucleus-nucleus collisions when applied to smaller systems. Intermediate-sized, light ion collisions will offer key insight into the system-size dependence of the interplay between jet energy loss and jet flow effects. To make quantitative predictions, we extend a semi-analytic jet quenching framework by coupling it to state-of-the-art event-by-event hydrodynamics and, for the first time, incorporate pre-equilibrium energy loss via the hydrodynamic attractor. A Bayesian analysis shows that an early-time onset of energy loss is compatible with RHIC and LHC measurements of jet suppression and jet elliptic flow in large systems, as well as hadron suppression, with the exception of hadron elliptic flow. Using these constraints, we predict both hadron and jet quenching observables in oxygen-oxygen collisions, finding sizable energy loss that exceeds the no-quenching baseline.

    Comments:
    5 pages, 3 figures, with more 3 figures in the appendix. Updated version matches the published version
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Theory (hep-th); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2509.19430 [pdf]
    PRC(2026)·25 citations
  2. 03

    [Submitted on 23 Sept 2025] (cross-list from nucl-ex)

    Multi-Cycle PWR Modeling with DRAGON and PARCS: Implications for Nuclear Data Assessment

    Benjamin Arthur Hugo Meunier

    Nuclear data libraries serve as the foundation for all calculations in the nuclear field. Their quality directly affects the accuracy of computations. When new nuclear data libraries are released, they must undergo validation through the use of integral experimental data. This work introduces an automated simulation pipeline that converts raw nuclear data into predictions for various reactors, significantly enhancing the validation process. This pipeline allows for the assessment of potential biases in integral measurement predictions for nuclear power plants before the release of a new nuclear data library. To achieve this, an implementation of history variables in DRAGON was developed to determine the macroscopic cross sections of the nodal code PARCS. This method has been verified for seven depletion cycles across three pressurised water reactors (PWRs) against publicly available data. The errors on the predictions are in the uncertainty range attributed to variations in nuclear data. Additionally, a methodology to assess the quality of novel nuclear data libraries against experimental measurements in PWRs is presented.

    Comments:
    65 pages, 18 figures
    Subjects:
    Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2509.19450 [pdf]
    0 citations
  3. 04

    [Submitted on 24 Sept 2025] (cross-list from hep-ph)

    Phenomenological constraints on QCD transport with quantified theory uncertainties

    Sunil Jaiswal🇺🇸

    We present data-driven, state-of-the-art constraints on the temperature-dependent specific shear and bulk viscosities of the quark-gluon plasma from Pb-Pb collisions at . We perform global Bayesian calibration using the JETSCAPE multistage framework with two particlization ansätze, Grad 14-moment and first-order Chapman-Enskog, and quantify theoretical uncertainties via a centrality-dependent model discrepancy term. When theoretical uncertainties are neglected, the specific bulk viscosity and some model parameters inferred using the two ansätze exhibit clear tension. Once theoretical uncertainties are quantified, the Grad and Chapman-Enskog posteriors for all model parameters become almost statistically indistinguishable and yield reliable, uncertainty-aware constraints. Furthermore, the learned discrepancy identifies where each model falls short for specific observables and centrality classes, providing insight into model limitations.

    Comments:
    9 pages, 7 figures, and 1 table. Expanded the discussion in Section 3; several minor additions/modifications elsewhere. Results unchanged. Updated to match the published version
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2509.19759 [pdf]
    PLB(2026)·4 citations
  4. 05

    [Submitted on 24 Sept 2025] (cross-list from hep-ph)

    Nonlinear dynamics of jet quenching

    Yacine Mehtar-Tani🇺🇸

    We present an analytic framework for jet quenching in dense QCD matter that unifies medium-induced branching with vacuum collinear evolution. Energy transported outside the jet region is governed by a non-linear rate equation that resums arbitrary-angle gluon splittings, each enhanced by the medium length . We show that for asymptotically large energies the energy-loss distribution for a single hard parton exhibits an exponential (generalized Poisson) behavior that provides the initial condition for a non-linear, DGLAP-like evolution that resums collinear logarithms associated with early in-vacuum fragmentation and with the angular resolution of the medium. This framework allows a systematic resummation of parton branching contributions to jet energy loss.

    Comments:
    4 pages, Quark Matter 2025 Proceedings
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2509.19850 [pdf]
    EPJ Web Conf.(2026)·0 citations
  5. 06

    [Submitted on 24 Sept 2025] (cross-list from hep-ph)

    Tensor spin polarization induced by curved freeze-out hypersurface

    Zhong-Hua Zhang🇨🇳 · Xu-Guang Huang🇨🇳

    We investigate how the curvature of the freeze-out hypersurface polarizes massive vector bosons in relativistic heavy-ion collisions. Starting from the Proca Lagrangian and using the Wigner function formalism, we perform a systematic gradient expansion to obtain a covariant spin-polarization tensor expressed in terms of hydrodynamic fields and the curvature tensor of the freeze-out hypersurface. Analytic results for Bjorken and Gubser flows show that curvature anisotropy generates a nonzero tensor polarization. For meson, we estimate the curvature contribution to its spin alignment as to . We also find that the curvature contribution grows as the system size decreases. A rough estimate for central O-O collisions gives a spin alignment of order , suggesting that spin-alignment measurements in such small systems may provide a clean probe of this geometric effect.

    Comments:
    23 pages, 1 figure
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2509.20200 [pdf]
    PRD(2026)·2 citations
  6. 07

    [Submitted on 24 Sept 2025] (cross-list from hep-ph)

    Collinear Structure of Nonlinear Small- Evolution

    Renaud Boussarie🇫🇷 · Paul Caucal🇫🇷 · Yacine Mehtar-Tani🇺🇸

    We introduce a novel approach to high-energy QCD factorization of cross-sections for processes involving a dilute projectile and a dense target. Our method preserves the factorization between "fast" and "slow" modes in the longitudinal momentum for a projectile moving along the positive light-cone direction, making it compatible with higher-order loop computations done within the standard formulation of the Color Glass Condensate (CGC) effective field theory. Moreover, it eliminates the anomalous double collinear logarithms that typically hinder the convergence of perturbation theory at small-. Our scheme amounts to a change of basis in the space of CGC operators, introducing an arbitrary transverse scale dependence while leaving physical cross-sections invariant. Implementing this scheme requires a modification of the high-energy renormalization group equation for the CGC operators, which we explicitly derive at next-to-leading order (NLO) and in the non-linear regime for the case of the dipole operator and the DIS impact factor. This general framework provides a consistent and systematic prescription for computing observables in the small- regime of QCD, free from collinear instabilities.

    Comments:
    31 pages
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    2509.20236 [pdf]
    8 citations
  7. 08

    [Submitted on 24 Sept 2025] (cross-list from hep-ph)

    Studies of beauty hadron and non-prompt charm hadron production in pp collisions at =13 TeV within a transport model approach

    Jialin He🇨🇳 · Xinye Peng🇨🇳 · Xiaoming Zhang🇨🇳 · Liang Zheng🇨🇳

    In high-energy proton proton () collisions at the LHC, non-prompt charm hadrons, originating from beauty hadron decays, provide a valuable probe for beauty quark dynamics, particularly at low transverse momentum where direct beauty measurements are challenging. We employ A Multi-Phase Transport Model (AMPT) of string melting version coupled with PYTHIA8 initial conditions to study the beauty hadron and non-prompt charm hadron productions in collisions at TeV. In this work, the beauty quark mass during the generation stage has been increased to reproduce the measured cross section, and a beauty flavor specific coalescence parameter is introduced to match LHCb measurements of beauty baryon to meson ratios. With these refinements, AMPT achieves a reasonable agreement with experimental data on beauty hadron yields and non-prompt charm hadron production from ALICE and LHCb. We present the transverse momentum and multiplicity dependence of non-prompt to prompt charm hadron ratios, providing new insights into the interplay between beauty quark production and hadronization process. We emphasize that the multiplicity dependence of the non-prompt to prompt charm hadron productions can be useful to constrain the flavor dependences of the coalescence dynamics. This work establishes a unified framework for future studies of heavy quark transport and collective flow behavior in small collision systems.

    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
    arXiv:
    2509.20291 [pdf]
    PRD(2026)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE