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Nuclear Theory·nucl-th

Friday·June 21, 2019

7 papers—4 primary·3 cross-listed

All7Primary4Cross-lists3
  1. 01

    [Submitted on 19 Jun 2019]

    Electromagnetic stress on nucleon structure

    Benjamin Koch🇨🇱

    External electromagnetic fields can provoke stress, and thus modifications of the internal structure of nucleons. Working with this hypothesis, one can derive a simple description of the charge dependence of the EMC effect. This first result is confirmed by two explicit models of the structure functions of deformed nucleons in the atomic nucleus. For large nuclei a continuous model is used. For small nuclei a discrete distribution of nuclear matter gives better results.

    Comments:
    13 pages, 15 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1906.08276 [pdf]
    NPA(2020)·1 citation
  2. 02

    [Submitted on 19 Jun 2019]

    Bag-type Model with Fractal Structure

    Evandro Andrade II🇧🇷 · Airton Deppman🇧🇷 · Eugenio Megias🇪🇸 · Débora P. Menezes🇧🇷 · Tiago Nunes da Silva🇧🇷

    In this work we present a bag-type model within a non-extensive statistics applied to the description of the properties of a hadronic system with an underlying fractal structure. The non-extensive ideal gas inside the bag is determined by the grand canonical partition function from which pressure, energy and particle density as well as temperature and chemical potential are obtained for the hadronic system. These quantities are studied in the approximation of fixed mass for all bag constituents but also for discrete and continuum masses. In all cases, the freeze-out line, corresponding to the energy per particle equal to 1 GeV and the lines corresponding to a fractal structure inside the proton volume are obtained. Finally, the pressure on the bag surface of the proton is calculated and the resulting value obtained.

    Comments:
    19 pages, 16 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1906.08301 [pdf]
    PRD(2020)·11 citations
  3. 03

    [Submitted on 20 Jun 2019]

    The Structure of the Hadron-Quark Reaction Zone

    Amir Ouyed🇨🇦 · Rachid Ouyed🇨🇦 · Prashanth Jaikumar🇺🇸

    Hadron-quark combustion in dense matter is a central topic in the study of phases in compact stars and their high-energy astrophysics. We critically review the literature on hadron-quark combustion, dividing them into a "first wave" that treats the problem as a steady-state burning with or without constraints of mechanical equilibrium, and a "second wave" which uses numerical techniques to resolve the burning front and solves the underlying Partial Differential Equations for the chemistry of the burning front under less restrictive conditions. We detail the inaccuracies that the second wave amends over the first wave, and highlight crucial differences between various approaches in the second wave. We also include results from time-dependent simulations of the reaction zone that include a hadronic EOS, neutrinos, and self-consistent thermodynamics without using parameterized shortcuts.

    Comments:
    9 pages, 2 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
    arXiv:
    1906.08404 [pdf]
    Universe(2019)·4 citations
  5. 05

    [Submitted on 19 Jun 2019] (cross-list from cs.LG)

    Solver Recommendation For Transport Problems in Slabs Using Machine Learning

    Jinzhao Chen · Japan K. Patel · Richard Vasques

    The use of machine learning algorithms to address classification problems is on the rise in many research areas. The current study is aimed at testing the potential of using such algorithms to auto-select the best solvers for transport problems in uniform slabs. Three solvers are used in this work: Richardson, diffusion synthetic acceleration, and nonlinear diffusion acceleration. Three parameters are manipulated to create different transport problem scenarios. Five machine learning algorithms are applied: linear discriminant analysis, K-nearest neighbors, support vector machine, random forest, and neural networks. We present and analyze the results of these algorithms for the test problems, showing that random forest and K-nearest neighbors are potentially the best suited candidates for this type of classification problem.

    Comments:
    Accepted -- The International Conference on Mathematics and Computational Methods applied to Nuclear Science and Engineering (M&C 2019), Portland, OR
    Subjects:
    Machine Learning (cs.LG); Nuclear Theory (nucl-th); Machine Learning (stat.ML)
    arXiv:
    1906.08259 [pdf]
    0 citations
  6. 06

    [Submitted on 20 Jun 2019] (cross-list from astro-ph.HE)

    Finite-temperature Equations of State for Neutron Star Mergers

    Paul M. Chesler🇺🇸 · Niko Jokela🇫🇮 · Abraham Loeb🇺🇸 · Aleksi Vuorinen🇫🇮

    The detection of gravitational waves from a neutron star merger has opened up the possibility of detecting the presence or creation of deconfined quark matter using the gravitational wave signal. To investigate this possibility, we construct a family of neutron star matter equations of state at nonzero density and temperature by combining state-of-the-art nuclear matter equations of state with holographic equations of state for strongly interacting quark matter. The emerging picture consistently points toward a strong first order deconfinement transition, with a temperature-dependent critical density and latent heat that we quantitatively examine. Recent neutron star mass measurements are further used to discriminate between the different equations of state obtained, leaving a tightly constrained family of preferred equations of state.

    Comments:
    8 pages, 6 figures; v2: new table and figure, refs. and discussion added, revised and published version; ancillary material with v1
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    1906.08440 [pdf]
    PRD(2019)·53 citations
  7. 07

    [Submitted on 20 Jun 2019] (cross-list from nucl-ex)

    Emerging collectivity from the nuclear structure of Xe: Inelastic neutron scattering studies and shell-model calculations

    E. E. Peters · A. E. Stuchbery · A. Chakraborty · B. P. Crider · S. F. Ashley · A. Kumar · M. T. McEllistrem · F. M. Prados-Estévez · S. W. Yates

    Inelastic neutron scattering was used to study the low-lying nuclear structure of Xe. A comprehensive level scheme is presented, as well as new level lifetimes, multipole mixing ratios, branching ratios, and transition probabilities. Comparisons of these data as well as previously measured strengths and factors are made with new shell-model calculations for Xe to explore the emergence of collectivity in the Xe isotopes with < 82 near the closed shell.

    Subjects:
    Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1906.08753 [pdf]
    PRC(2019)·26 citations

Affiliations

first authorsco-authorsvia INSPIRE