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Nuclear Theory·nucl-th

Friday·August 28, 2020

5 papers—2 primary·3 cross-listed

All5Primary2Cross-lists3
  1. 01

    [Submitted on 26 Aug 2020]

    Learning about the QCD medium using electromagnetic and weak probes

    Gojko Vujanovic🇺🇸

    Recent theoretical developments concerning radiation of electromagnetic and weak probes in ultra-relativistic heavy-ion collisions is overviewed. These proceedings focus on electromagnetic probes and briefly cover weak probes. An outlook regarding the future use of electromagnetic probes is formulated whereby a quantitative Bayesian comparison, simultaneously employing electromagnetic and hadronic calculations of experimental observables against data, is highlighted as a path towards a better understanding of the properties of the QCD medium.

    Comments:
    8 pages, 2 figures, Proceedings for the plenary talk given at the 10th International Conference on Hard and Electromagnetic Probes of High-Energy Nuclear Collisions (Hard Probes 2020), June 1-5, 2020
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    2008.11843 [pdf]
    PoS(2021)·0 citations
  2. 02

    [Submitted on 27 Aug 2020]

    Neutron-rich calcium isotopes within realistic Gamow shell model calculations with continuum coupling

    J. G. Li · B. S. Hu · Q. Wu · Y. Gao · S. J. Dai · F. R. Xu

    Based on the realistic nuclear force of the high-precision CD-Bonn potential, we have performed comprehensive calculations for neutron-rich calcium isotopes using the Gamow shell model (GSM) which includes resonance and continuum. The realistic GSM calculations produce well binding energies, one- and two-neutron separation energies, predicting that Ca is the heaviest bound odd isotope and Ca is the dripline nucleus. Resonant states are predicted, which provides useful information for future experiments on particle emissions in neutron-rich calcium isotopes. Shell evolutions in the calcium chain around neutron numbers \textit{N} = 32, 34 and 40 are understood by calculating effective single-particle energies, the excitation energies of the first states and two-neutron separation energies. The calculations support shell closures at Ca (\textit{N} = 32) and Ca (\textit{N} = 34) but show a weakening of shell closure at Ca (\textit{N} = 40). The possible shell closure at Ca (\textit{N} = 50) is predicted.

    Comments:
    24 pages, 6 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2008.11948 [pdf]
    PRC(2020)·31 citations
  3. 03

    [Submitted on 27 Aug 2020] (cross-list from hep-ph)

    Strange quark helicity in the proton from chiral effective theory

    X.G. Wang🇦🇺 · Chueng-Ryong Ji🇺🇸 · W. Melnitchouk🇺🇸 · Y. Salamu🇨🇳 · A.W. Thomas🇦🇺 · P. Wang🇨🇳

    We compute the helicity-dependent strange quark distribution in the proton in the framework of chiral effective theory. Starting from the most general chiral SU(3) Lagrangian that respects Lorentz and gauge invariance, we derive the complete set of hadronic splitting functions at the one meson loop level, including the octet and decuplet rainbow, tadpole, Kroll-Ruderman and octet-decuplet transition configurations. By matching hadronic and quark level operators, we obtain generalized convolution formulas for the quark distributions in the proton in terms of hadronic splitting functions and quark distributions in the hadronic configurations, and from these derive model-independent relations for the leading nonanalytic behavior of their moments. Within the limits of parameters of the Pauli-Villars regulators derived from inclusive hyperon production, we find that the polarized strange quark distribution is rather small and mostly negative.

    Comments:
    43 pages, 4 figures, 1 table
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
    arXiv:
    2008.11902 [pdf]
    PRD(2020)·7 citations
  4. 04

    [Submitted on 27 Aug 2020] (cross-list from hep-ph)

    Heating triangle singularities in heavy ion collisions

    Luciano M. Abreu (Univ. Federal Bahia)🇧🇷 · Felipe J. Llanes-Estrada (Univ. Complutense Madrid)🇪🇸

    We predict that triangle singularities of hadron spectroscopy can be strongly affected in heavy ion collisions. To do it we examine various effects on the singularity-inducing triangle loop of finite temperature in the terminal hadron phase. It appears that peaks seen in central heavy ion collisions are more likely to be hadrons than rescattering effects under two conditions. First, the flight-time of the intermediate hadron state must be comparable to the lifetime of the equilibrated fireball (else, the reaction mostly happens in vacuo after freeze out). Second, the medium effect over the triangle-loop particle mass or width must be sizeable. When these (easily checked) conditions are met, the medium quickly reduces the singularity: at T about 150 MeV, even by two orders of magnitude, acting then as a spectroscopic filter.

    Comments:
    9 pages, 13 plots
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2008.12031 [pdf]
    EPJC(2021)·15 citations
  5. 05

    [Submitted on 26 Aug 2020] (cross-list from hep-ph)

    Inverse catalysis effect of quark anomalous magnetic moment to chiral restoration and deconfinement phase transitions

    Jie Mei🇨🇳 · Shijun Mao🇨🇳

    The effect of quark anomalous magnetic moment (AMM) to chiral restoration and deconfinement phase transitions under magnetic fields is investigated in a Pauli-Villars regularized PNJL model. A linear-in- term for quark anomalous magnetic moment is introduced to the Lagrangian density of our model, and it plays the role of inverse catalysis to the phase transitions. With fixed magnetic field, the critical temperature decreases with quark AMM. When fixing quark AMM, the critical temperature increases with magnetic field for a small quark AMM, but decreases with magnetic field for a large quark AMM. The critical temperature of chiral restoration and deconfinement phase transitions is determined by the two competing factors, the catalysis effect of magnetic field and inverse catalysis of quark anomalous magnetic moment.

    Comments:
    5 pages, 3 figures. arXiv admin note: text overlap with arXiv:1712.06062
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2008.12123 [pdf]
    PRD(2020)·48 citations

Affiliations

first authorsco-authorsvia INSPIRE