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Nuclear Theory·nucl-th

Friday·August 4, 2017

4 papers—2 primary·2 cross-listed

All4Primary2Cross-lists2
  1. 01

    [Submitted on 2 Aug 2017]

    Coarse graining the Bethe-Goldstone equation: nucleon-nucleon high momentum components

    I. Ruiz Simo · R. Navarro Perez · J.E. Amaro · E. Ruiz Arriola

    The delta-shell representation of the nuclear force allows a simplified treatment of nuclear correlations. We show how this applies to the Bethe-Goldstone equation as an integral equation in coordinate space with a few mesh points, which is solved by inversion of a 5-dimensional square matrix in the single channel cases and a matrix for the tensor-coupled channels. This allows us to readily obtain the high momentum distribution, for all partial waves, of a back-to-back correlated nucleon pair in nuclear matter. We find that the probability of finding a high-momentum correlated neutron-proton pair is about 18 times that of a proton-proton one, as a result of the strong tensor force, thus confirming in an independent way previous results and measurements.

    Comments:
    Equation (2) is wrong, and all the results of the article based on that equation for the coupled nucleon partial waves are, consequently, wrong as well
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1708.00878 [pdf]
    PRC(2017)·7 citations
  2. 02

    [Submitted on 3 Aug 2017]

    Neutron matter within QCD sum rules

    Bao-Jun Cai🇨🇳 · Lie-Wen Chen🇨🇳

    Equation of state (EOS) of pure neutron matter (PNM) is studied in QCD sum rules (QCDSR). It is found that the QCDSR results on EOS of PNM are in good agreement with predictions by current advanced microscopic many-body theories. Moreover, the higher-order density terms in quark condensates are shown to be important to describe the empirical EOS of PNM in the density region around and above nuclear saturation density although they play minor role at subsaturation densities. The chiral condensates in PNM are also studied, and our results indicate that the higher-order density terms in quark condensates, which are introduced to reasonably describe the empirical EOS of PNM at suprasaturation densities, tend to hinder the appearance of chiral symmetry restoration in PNM at high densities.

    Comments:
    7 pages, 2 figures. Discussions added and presentation improved. Accepted version to appear in PRC
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1708.01010 [pdf]
    PRC(2018)·5 citations
  3. 03

    [Submitted on 2 Aug 2017] (cross-list from hep-ph)

    Hadron Resonance Gas with Repulsive Interactions and Fluctuations of Conserved Charges

    P. Huovinen🇵🇱 · P. Petreczky🇺🇸

    We discuss the role of repulsive baryon-baryon interactions in a hadron gas using relativistic virial expansion and repulsive mean field approaches. The fluctuations of the baryon number as well as strangeness-baryon correlations are calculated in the hadron resonance gas with repulsive interactions and compared with the recent lattice QCD results. In particular, we calculate the difference between the second and fourth order fluctuations and correlations of baryon number and strangeness, that have been proposed as probes of deconfinement. We show that for not too high temperatures these differences could be understood in terms of repulsive interactions.

    Comments:
    12pages, 2 figures, ReVTeX, published version, unexpanded mean field results added
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
    arXiv:
    1708.00879 [pdf]
    PLB(2018)·82 citations
  4. 04

    [Submitted on 3 Aug 2017] (cross-list from hep-ph)

    Hard photoproduction of a diphoton with a large invariant mass

    A. Pedrak🇵🇱 · B. Pire🇫🇷 · L. Szymanowski🇵🇱 · J. Wagner🇵🇱

    The electromagnetic probe has proven to be a very efficient way to access the dimensional structure of the nucleon, particularly thanks to the exclusive Compton processes. We explore the hard photoproduction of a large invariant mass diphoton in the kinematical regime where the diphoton is nearly forward and its invariant mass is the hard scale enabling to factorize the scattering amplitude in terms of generalized parton distributions. This amplitude has a very peculiar and interesting analytic structure. We calculate unpolarized cross sections and the angular asymmetry triggered by a linearly polarized photon beam.

    Comments:
    8 pages, 9 figures. Version 2, as to be published in Phys Rev D96, contains minor improvements including a brief comparison of different GPD models and a brief discussion of the very high energy behavior of the cross section. Version 3 includes the erratum published in Phys Rev D100 (2019) no.3, 039901
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1708.01043 [pdf]
    PRD(2017)·62 citations

Affiliations

first authorsco-authorsvia INSPIRE