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Nuclear Theory·nucl-th

Thursday·May 23, 2019

3 papers—2 primary·1 cross-listed

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  1. 01

    [Submitted on 22 May 2019]

    Constraining level densities using spectral data

    G.P.A. Nobre · D. A. Brown · M. W. Herman

    Several models of level densities exist and they often make simplified assumptions regarding the overall behavior of the total level densities (LD) and the intrinsic spin and parity distributions of the excited states. Normally, such LD models are constrained only by the measured , i.e. the density of levels at the neutron separation energy of the compound nucleus (target plus neutron), and the sometimes subjective extrapolation of discrete levels. In this work we use microscopic Hartree-Fock-Bogoliubov (HFB) level densities, which intrinsically provide more realistic spin and parity distributions, and associate variations predicted by the HFB model with the observed double-differential cross sections at low outgoing neutron energy, region that is dominated by the LD input. With this approach we are able to perform fits of the LD based on actual experimental data, constraining the model and ensuring its consistency. This approach can be particularly useful in extrapolating the LD to nuclei for which high-excited discrete levels and/or values of are unknown. It also predicts inelastic gamma (n,n) cross sections that in some cases can differ significantly from more standard LD models such as Gilbert-Cameron.

    Comments:
    6 pages, 4 figures. Submitted to the proceedings of the CNR*18 conference
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1905.09194 [pdf]
    Springer Proc.Phys.(2020)·1 citation
  2. 02

    [Submitted on 22 May 2019]

    Hadronization and Charm-Hadron Ratios in Heavy-Ion Collisions

    Min He🇨🇳 · Ralf Rapp🇺🇸

    Understanding the hadronization of the quark-gluon plasma (QGP) remains a challenging problem in the study of strong-interaction matter as produced in ultrarelativistic heavy-ion collisions (URHICs). The large mass of heavy quarks renders them excellent tracers of the color neutralization process of the QGP when they convert into various heavy-flavor (HF) hadrons. We develop a 4-momentum conserving recombination model for HF mesons and baryons that recovers the thermal and chemical equilibrium limits and accounts for space-momentum correlations (SMCs) of heavy quarks with partons of the hydrodynamically expanding QGP, thereby resolving a long-standing problem in quark coalescence models. The SMCs enhance the recombination of fast-moving heavy quarks with high-flow thermal quarks in the outer regions of the fireball. We also improve the hadro-chemistry with "missing" charm-baryon states, previously found to describe the large ratio observed in proton-proton collisions. Both SMCs and hadro-chemistry, as part of our HF hydro-Langevin-recombination model for the strongly coupled QGP, importantly figure in the description of recent data for the ratio and -meson elliptic flow in URHICs.

    Comments:
    6 pages, 5 figures, published version in Phys. Rev. Lett
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1905.09216 [pdf]
    PRL(2020)·179 citations
  3. 03

    [Submitted on 22 May 2019] (cross-list from hep-ph)

    Kaon form factor in holographic QCD

    Zainul Abidin🇮🇩 · Parada T. P. Hutauruk🇰🇷

    The kaon form factor in the spacelike region is calculated using a holographic QCD model with the "bottom-up" approach. We found that our result for the kaon form factor in low has a remarkable agreement with the existing data, where is the four-momentum transfer squared. The charge radius of the kaon, as well as the kaon decay constant, are found to be in a good agreement with the experiment data. We then predict the kaon form factor in the asymptotic region (larger ) showing behavior, which is consistent with the perturbative QCD prediction.

    Comments:
    8 pages, 3 figures, to appear in Phys. Rev. D
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1905.08953 [pdf]
    PRD(2019)·18 citations

Affiliations

first authorsco-authorsvia INSPIRE