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Nuclear Theory·nucl-th

Monday·November 6, 2023

8 papers—3 primary·5 cross-listed

All8Primary3Cross-lists5
  1. 04

    [Submitted on 2 Nov 2023] (cross-list from hep-lat)

    Quark Mass Dependence of Heavy Quark Diffusion Coefficient from Lattice QCD

    Luis Altenkort🇩🇪 · David de la Cruz🇩🇪 · Olaf Kaczmarek🇩🇪 · Rasmus Larsen🇳🇴 · Guy D. Moore🇩🇪 · Swagato Mukherjee🇺🇸 · Peter Petreczky🇺🇸 · Hai-Tao Shu🇺🇸 · Simon Stendebach🇩🇪

    We present the first study of the quark mass dependence of the heavy quark momentum and spatial diffusion coefficients using lattice QCD with light dynamical quarks corresponding to a pion mass of 320 MeV. We find that, for the temperature range 195 MeV 293 MeV, the spatial diffusion coefficients of the charm and bottom quarks are smaller than those obtained in phenomenological models that describe the spectra and elliptic flow of open heavy flavor hadrons.

    Comments:
    15 pages, 12 figures
    Subjects:
    High Energy Physics — Lattice (hep-lat); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2311.01525 [pdf]
    PRL(2024)·70 citations
  2. 05

    [Submitted on 2 Nov 2023] (cross-list from stat.ME)

    Local Bayesian Dirichlet mixing of imperfect models

    Vojtech Kejzlar · Léo Neufcourt · Witold Nazarewicz

    To improve the predictability of complex computational models in the experimentally-unknown domains, we propose a Bayesian statistical machine learning framework utilizing the Dirichlet distribution that combines results of several imperfect models. This framework can be viewed as an extension of Bayesian stacking. To illustrate the method, we study the ability of Bayesian model averaging and mixing techniques to mine nuclear masses. We show that the global and local mixtures of models reach excellent performance on both prediction accuracy and uncertainty quantification and are preferable to classical Bayesian model averaging. Additionally, our statistical analysis indicates that improving model predictions through mixing rather than mixing of corrected models leads to more robust extrapolations.

    Subjects:
    stat.ME (stat.ME); Nuclear Theory (nucl-th); Machine Learning (stat.ML)
    arXiv:
    2311.01596 [pdf]
    Sci.Rep.(2023)·17 citations
  3. 06

    [Submitted on 2 Nov 2023] (cross-list from hep-ph)

    Developing predictions for pion fragmentation functions

    H.-Y. Xing🇨🇳 · Z.-Q. Yao🇮🇹 · B.-L. Li🇨🇳 · D. Binosi🇮🇹 · Z.-F. Cui🇨🇳 · C. D. Roberts🇨🇳

    Exploiting crossing symmetry, the hadron scale pion valence quark distribution function is used to predict the kindred elementary valence quark fragmentation function (FF). This function defines the kernel of a quark jet fragmentation equation, which is solved to obtain the full pion FFs. After evolution to a scale typical of FF fits to data, the results for quark FFs are seen to compare favourably with such fits. However, the gluon FF is markedly different. Notably, although FF evolution equations do not themselves guarantee momentum conservation, inclusion of a gluon FF which, for four quark flavours, distributes roughly 11% of the total light-front momentum fraction, is sufficient to restore momentum conservation under evolution. Overall, significant uncertainty is attached to FFs determined via fits to data; hence, the features of the predictions described herein could potentially provide useful guidance for future such studies.

    Comments:
    9 pages, 4 figures
    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:
    2311.01613 [pdf]
    EPJC(2024)·18 citations
  4. 07

    [Submitted on 3 Nov 2023] (cross-list from nucl-ex)

    Nuclear density dependence of polarization transfer in quasi-elastic reactions

    T. Kolar🇮🇱 · W. Cosyn🇺🇸 · C. Giusti🇮🇹 · P. Achenbach🇩🇪 · A. Ashkenazi🇮🇱 · R. Böhm🇩🇪 · D. Bosnar🇭🇷 · T. Brecelj🇸🇮 · M. Christmann🇩🇪 · E. O. Cohen🇮🇱 · M. O. Distler🇩🇪 · L. Doria🇩🇪 and 43 other authors

    The ratio of the transverse and longitudinal component of polarization transfer to protons in the quasi-elastic reaction, , is sensitive to the proton's electromagnetic form factor ratio, . To explore density-dependent in-medium modifications, a comparison of polarization transfer ratios involving protons from distinct nuclear shells, each with different local nuclear densities, has been proposed. In this study, we present such comparisons between four shells, , in and , in . In an effort to account for other many-body effects that may differ between shells, we use a state-of-the-art relativistic distorted-wave impulse-approximation (RDWIA) calculation and present the double ratios, as well as the super ratios, , for chosen shells A and B, as a function of effective local nuclear densities. We find that double ratios for individual shells show a dependence on the probed effective nuclear densities. Studying the ratios, we observed a systematic variation between pairs of higher- and lower-density shells.

    Subjects:
    Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2311.01935 [pdf]
    PRC(2024)·2 citations
  5. 08

    [Submitted on 3 Nov 2023] (cross-list from hep-ph)

    Production of the dibaryon as a weakly bound system in collisions

    Tian-Chen Wu🇨🇳 · Atsushi Hosaka🇯🇵 · Li-Sheng Geng🇨🇳

    The interaction plays an important role in our understanding on the long-anticipated -dibaryon. Recent lattice QCD calculations verified the attractive nature of the interaction. On the other hand, whether it is strong enough to generate a bound state remains inconclusive.In this work, assuming that it can generate a weakly bound state, we study the yields of the dibaryon for different binding energies in collisions at 7 TeV using the coalescence model and the transport model PACIAE. The yields are estimated first numerically and then analytically adopting a Yukawa-type wave function. In particular, we find that in the weak binding limit, there exists a universal relation between the yield and the binding energy, valid for collisions.

    Comments:
    7 pages, 6 figures; comments welcome
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2311.02022 [pdf]
    PRD(2024)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE