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Nuclear Theory·nucl-th

Wednesday·January 11, 2023

9 papers—4 primary·5 cross-listed

All9Primary4Cross-lists5
  1. 05

    [Submitted on 9 Jan 2023] (cross-list from hep-th)

    1+1D Hadrons Minimize their Biparton Renyi Free Energy

    Pouya Asadi🇺🇸 · Varun Vaidya🇺🇸

    We use a variational method to calculate the spectrum and the parton distribution function of ground state hadrons of various gauge theories in 1+1 dimensions. The template functions in our method minimize a free energy functional defined as a combination of free valence partons' kinetic energy on the lightcone and the Renyi entanglement entropy of biparton subsystems. Our results show that hadrons in these theories minimize the proposed free energy. The success of this technique motivates applying it to confining gauge theories in higher dimensions.

    Comments:
    5 two-column pages, 5 figures
    Subjects:
    High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
    arXiv:
    2301.03611 [pdf]
    PRD(2023)·15 citations
  2. 06

    [Submitted on 10 Jan 2023] (cross-list from nucl-ex)

    Multiple Mechanisms in Proton-Induced Nucleon Removal at 100 MeV/Nucleon

    T. Pohl🇩🇪 · Y. L. Sun🇩🇪 · A. Obertelli🇩🇪 · J. Lee🇨🇳 · M. Gomez-Ramos🇪🇸 · K. Ogata🇯🇵 · K. Yoshida🇯🇵 · B.S. Cai🇨🇳 · C.X. Yuan🇨🇳 · B. A. Brown🇺🇸 · H. Baba🇯🇵 · D. Beaumel🇫🇷 and 39 other authors

    We report on the first proton-induced single proton- and neutron-removal reactions from the neutron-deficient O nucleus with large Fermi-surface asymmetry = 18.6 MeV at 100 MeV/nucleon, a widely used energy regime for rare-isotope studies. The measured inclusive cross sections and parallel momentum distributions of the N and O residues are compared to the state-of-the-art reaction models, with nuclear structure inputs from many-body shell-model calculations. Our results provide the first quantitative contributions of multiple reaction mechanisms including the quasifree knockout, inelastic scattering and nucleon transfer processes. It is shown that the inelastic scattering and nucleon transfer, usually neglected at such energy regime, contribute about 50% and 30% to the loosely bound proton and deeply bound neutron removal, respectively. These multiple reaction mechanisms should be considered in analyses of inclusive one-nucleon removal cross sections measured at intermediate energies for quantitative investigation of single-particle strengths and correlations in atomic nuclei.

    Subjects:
    Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2301.03836 [pdf]
    PRL(2023)·17 citations
  3. 07

    [Submitted on 10 Jan 2023] (cross-list from cond-mat.stat-mech)

    Generational variance reduction in Monte Carlo criticality simulations as a way of mitigating unwanted correlations

    Kévin Fröhlicher · Eric Dumonteil · Loïc Thulliez · Julien Taforeau · Mariya Brovchenko

    Monte Carlo criticality simulations are widely used in nuclear safety demonstrations, as they offer an arbitrarily precise estimation of global and local tallies while making very few assumptions. However, since the inception of such numerical approaches, it is well known that bias might affect both the estimation of errors on these tallies and the tallies themselves. In particular, stochastic modeling approaches developed in the past decade have shed light on the prominent role played by spatial correlations through a phenomenon called neutron clustering. This effect is particularly of great significance when simulating loosely coupled systems (i.e., with a high dominance ratio). In order to tackle this problem, this paper proposes to recast the power iteration technique of Monte Carlo criticality codes into a variance reduction technique called Adaptative Multilevel Splitting. The central idea is that iterating over neutron generations can be seen as pushing a sub-population of neutrons towards a generational detector (instead of a spatial detector as variance reduction techniques usually do). While both approaches allow for neutron population control, the former blindly removes or splits neutrons. In contrast, the latter optimizes spatial, generational, and spectral attributes of neutrons when they are removed or split through an adjoint flux estimation, hence tempering both generational and spatial correlations. This is illustrated in the present article with a simple case of a bare slab reactor in the one speed theory on which the Adaptive Multilevel Splitting was applied and compared to variations of the Monte Carlo power iteration method used in neutron transport. Besides looking at the resulting efficiency of the methods, this work also aims at highlighting the main mechanisms of the Adaptive Multilevel Splitting in criticality calculations.

    Comments:
    38 pages, 4 tables, 18 figures
    Subjects:
    Statistical Mechanics (cond-mat.stat-mech); Nuclear Theory (nucl-th); Computational Physics (physics.comp-ph)
    arXiv:
    2301.03882 [pdf]
    Nucl.Sci.Eng.(2024)·0 citations
  4. 08

    [Submitted on 10 Jan 2023] (cross-list from nucl-ex)

    Nuclear decay as a probe for physics beyond the Standard Model

    M. Brodeur🇺🇸 · N. Buzinsky🇺🇸 · M. A. Caprio🇺🇸 · V. Cirigliano🇺🇸 · J. A. Clark🇺🇸 · P. J. Fasano🇺🇸 · J. A. Formaggio🇺🇸 · A. T. Gallant🇺🇸 · A. Garcia🇺🇸 · S. Gandolfi🇺🇸 · S. Gardner🇺🇸 · A. Glick-Magid🇺🇸 and 34 other authors

    This white paper was submitted to the 2022 Fundamental Symmetries, Neutrons, and Neutrinos (FSNN) Town Hall Meeting in preparation for the next NSAC Long Range Plan. We advocate to support current and future theoretical and experimental searches for physics beyond the Standard Model using nuclear decay.

    Comments:
    12 pages, 2 figures, White paper submitted to the 2022 Fundamental Symmetries, Neutrons, and Neutrinos (FSNN) Town Hall Meeting at the University of North Carolina Chapel Hill
    Subjects:
    Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2301.03975 [pdf]
    26 citations
  5. 09

    [Submitted on 10 Jan 2023] (cross-list from hep-ph)

    Role of chemical potential at kinetic freeze-out using Tsallis non-extensive statistics in proton-proton collisions at the Large Hadron Collider

    Girija Sankar Pradhan🇮🇳 · Dushmanta Sahu🇮🇳 · Rutuparna Rath🇮🇹 · Raghunath Sahoo🇮🇳 · Jean Cleymans🇿🇦

    The charged-particle transverse momentum spectra (-spectra) measured by the ALICE collaboration for collisions at 7 and 13 TeV have been studied using a thermodynamically consistent form of Tsallis non-extensive statistics. The Tsallis distribution function is fitted to the -spectra and the results are analyzed as a function of final state charged-particle multiplicity for various light flavor and strange particles, such as . At the LHC energies, particles and antiparticles are produced in equal numbers. However, the equality of particle and antiparticle yields at the kinetic freeze-out may imply that they have the same but opposite chemical potential which is not necessarily zero. We use an alternative procedure that makes use of parameter redundancy, by introducing a finite chemical potential at the kinetic freeze-out stage. This article emphasizes the importance of the chemical potential of the system produced in collisions at the LHC energies using the Tsallis distribution function which brings the system to a single freeze-out scenario.

    Comments:
    Same as the published version in EPJA
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2301.04038 [pdf]
    EPJA(2024)·9 citations

Affiliations

first authorsco-authorsvia INSPIRE