PaperPanorama
FAQ

Nuclear Theory·nucl-th

Tuesday·December 10, 2024

14 papers—6 primary·8 cross-listed

All14Primary6Cross-lists8
  1. 01

    [Submitted on 7 Dec 2024]

    Signatures of Jet Drift in QGP Hard Probe Observables

    Joseph Bahder🇺🇸 · Hasan Rahman🇺🇸 · Matthew D. Sievert🇺🇸 · Ivan Vitev🇺🇸

    Hard probe tomography of the quark-gluon plasma (QGP) in heavy ion collisions has long been a preeminent goal of the high-energy nuclear physics program. In service of this goal, the isotropic modification of jets and high-energy hadrons has been studied in great detail at the leading-power (eikonal) level, with effects originating from sub-eikonal anisotropic interactions presumed to be small. We present the first investigation of sub-eikonal, collective-flow-induced asymmetric jet broadening (jet drift) in event-by-event TeV PbPb collisions at the Large Hadron Collider using the new Anisotropic Parton Evolution (APE) computational framework. We show that jet drift imparts a sizeable enhancement of elliptic flow () and increases the mean acoplanarity for low and intermediate energy particles ( GeV). Importantly, these novel modifications to hard probe observables are shown to survive averaging over events and collision geometry. They couple to the collective flow of the medium seen by the jet and encode information about the QGP dynamics inaccessible to studies considering only isotropic, eikonal level effects.

    Comments:
    8 pages, 5 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2412.05474 [pdf]
    PRResearch(2026)·14 citations
  2. 02

    [Submitted on 7 Dec 2024]

    Spin polarization of an expanding and rotating system

    Nora Weickgenannt🇫🇷 · Jean-Paul Blaizot🇫🇷

    We study the longitudinal spin polarization of a relativistic fluid of massive spin-1/2 particles undergoing a boost-invariant expansion in the longitudinal direction and rotating in the transverse plane. We express the polarization vector in terms of spin moments and derive closed equations of motion for the latter using spin kinetic theory with a nonlocal relaxation time approximation. These equations of motion are valid at any time of the evolution, from the free-streaming regime to the hydrodynamic regime. At late time, the polarization features contributions from gradients of the fluid velocity and of the temperature, that emerge from the nonlocal part of the collision term. Our results can be used to explore polarization phenomena in the context of heavy-ion collisions.

    Comments:
    34 pages
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2412.05733 [pdf]
    PRD(2025)·7 citations
  3. 03

    [Submitted on 8 Dec 2024]

    Large-scale shell-model study of 2ECEC process in Kr

    Deepak Patel · Praveen C. Srivastava

    In this work, we present the systematic study of ECEC process in the Kr using large-scale shell-model calculations with the GWBXG effective interaction. We first validate the efficiency of the utilized interaction by comparing the theoretical low-lying energy spectra, the kinematic moment of inertia, and reduced transition probabilities with the experimental data for both the parent and grand-daughter nuclei Kr and Se, respectively. Additionally, we examine the shell-model level densities of the states in the intermediate nucleus Br, comparing them with the predictions from the Back-shifted Fermi gas model. We analyze the variation of cumulative nuclear matrix elements (NMEs) for the ECEC process in Kr as a function of state energies in the intermediate nucleus Br up to the saturation level. Our estimated half-life for Kr, extracted from the shell-model predicted NMEs, shows good agreement with the experimental value. The Gamow-Teller transitions from the lowest state of Br via both the EC and -channels are also discussed.

    Comments:
    14 pages, 4 figures, Focus on Nuclear Science-ISNS-24, Physica Scripta 100, 015303 (2025)
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2412.05844 [pdf]
    Phys.Scripta(2025)·2 citations
  4. 04

    [Submitted on 8 Dec 2024]

    Implications of latest NICER data for the neutron star equation of state

    Len Brandes🇩🇪 · Wolfram Weise🇩🇪

    As an update to our previously performed Bayesian inference analyses of the neutron star matter equation-of-state and related quantities, the additional impact of the recently published NICER data of PSR J0437-4751 is examined. Including the mass and radius distributions of this pulsar in our data base results in modest shifts from previously inferred median posterior values of radii and central densities for representative and neutron stars: radii are reduced by about km to values of km and km (at the 68\% level), and central densities increase slightly to values of and (in units of equilibrium nuclear matter density, fm), i.e., they still fall below five times nuclear saturation density at the 68\% level. As a further significant result, the evidence established by analyzing Bayes factors for a negative trace anomaly measure, , inside heavy neutron stars is raised to strong.

    Comments:
    published version
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); Nuclear Experiment (nucl-ex)
    arXiv:
    2412.05923 [pdf]
    PRD(2025)·31 citations
  5. 05

    [Submitted on 9 Dec 2024]

    Identifying weak critical fluctuations of intermittency in heavy-ion collisions with topological machine learning

    Rui Wang🇨🇳 · Chengrui Qiu🇨🇳 · Chuan-Shen Hu🇸🇬 · Zhiming Li🇨🇳 · Yuanfang Wu🇨🇳

    Large density fluctuations of conserved charges have been proposed as a promising signature for exploring the QCD critical point in heavy-ion collisions. These fluctuations are expected to exhibit a fractal or scale-invariant behavior, which can be probed by intermittency analysis. Recent high-energy experimental studies reveal that the signal of critical fluctuations related to intermittency is very weak and thus could be easily obscured by the overwhelming background particles in the data sample. Employing a point cloud neural network with topological machine learning, we can successfully classify weak signal events from background noise by the extracted distinct topological features, and accurately determine the intermittency index for weak signal event samples.

    Comments:
    11 pages, 6 figures,published version
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    2412.06151 [pdf]
    PLB(2025)·6 citations
  6. 06

    [Submitted on 9 Dec 2024]

    Estimating theoretical uncertainties of the two-nucleon observables by using backpropagation

    K. Topolnicki · R. Skibiński · J. Golak

    We present a novel approach to calculating theoretical uncertainties in few-nucleon calculations, making use of automatic differentiation via backpropagation, which is particularly efficient when there are many input variables but only a few outputs. The methods described in this paper constitute tools that can be used to investigate the properties of scalar functions used to define nuclear potentials and quantify their contribution to the uncertainty of few nucleon calculations. We demonstrate these methods in deuteron bound state and nucleon - nucleon scattering calculations. Backpropagation, implemented in the Python pytorch library, is used to calculate the gradients with respect to model parameters and propagate errors from these parameters to the deuteron binding energy and selected phase-shift parameters. The uncertainty values obtained using this approach are validated by directly sampling from the potential parameters. We find very good agreement between two ways of estimating that uncertainty.

    Comments:
    11 pages, 7 figures, 5 tables
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2412.06304 [pdf]
    EPJA(2025)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE