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Nuclear Theory·nucl-th

Tuesday·May 11, 2021

19 papers—13 primary·6 cross-listed

All19Primary13Cross-lists6
  1. 14

    [Submitted on 4 Apr 2021] (cross-list from nucl-th)

    The chiral restored quark stars can exist in the universe

    Li-Qun Su🇨🇳 · Yan Yan🇨🇳 · Cheng-Ming Li🇨🇳 · Yong-Feng Huang🇨🇳 · Hongshi Zong🇨🇳

    In this paper, the equation of state (EOS) of deconfined quark stars is studied in the framework of the two-flavor NJL model, and the self-consistent mean field approximation is employed by introducing a parameter combining the original Lagrangian and the Fierz-transformed Lagrangian, , to measure the weights of different interaction channels. It is believed that the deconfinement of phase transition happens along with the chiral phase transition. Thus, due to the lack of description of confinement in the NJL model, the vacuum pressure is set to confine quarks at low densities, which is the pressure corresponding to the critical point of chiral phase transition. We find that deconfined quark stars can reach over two-solar-mass, and the bag constant therefore shifts from to as grows. In addition, the tidal deformability is yielded ranging from 253 to 482 along with the decrease of , which satisfies the astronomical constraint of for 1.4-solar-mass neutron stars.

    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
    arXiv:
    2104.01524 [pdf]
    0 citations
  2. 15

    [Submitted on 9 May 2021] (cross-list from hep-ph)

    QCD phase transition and equation of state of stellar strong interaction matter via Dyson-Schwinger equation approach

    Zhan Bai🇨🇳 · Yu-xin Liu🇨🇳

    We study the phase structure and phase transition of cold dense QCD matter via the Dyson-Schwinger equation approach. We take the rainbow approximation and the Gaussian-type gluon model. In order to guarantee that the quark number density begins to appear at the nuclear liquid-gas phase transition chemical potential, we propose a chemical potential dependent modification factor for the gluon model. We find that for the iso-symmetric quark matter, the modification reduces the chemical potential of the phase coexistence region of the first--order phase transition. We also implement the relativistic mean field theory to describe the hadron matter, and make use of the Maxwell and Gibbs construction method to study the phase transition of beta--equilibrium and charge neutral matter in compact stars. The results show that the phase transition will not happen in case of the Gaussian--type gluon model without any modification. The results also indicate that the upper boundary of the coexistence region should be larger than the current Nambu solution existing region. We also calculate the mass-radius relation of the compact stars, and find that the hadron-quark phase transition happens at too high chemical potential so that the maximum mass of the compact star is hardly affected by the hadron-quark phase transition.

    Comments:
    15 pages, 9 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2105.03947 [pdf]
    EPJC(2021)·11 citations
  3. 16

    [Submitted on 9 May 2021] (cross-list from hep-ph)

    Scale symmetry breaking, quantum anomalous energy and proton mass decomposition

    Xiangdong Ji🇺🇸 · Yizhuang Liu🇩🇪 · Andreas Schäfer🇵🇱

    We study the anomalous scale symmetry breaking effects on the proton mass in QCD due to quantum fluctuations at ultraviolet scales. We confirm that a novel contribution naturally arises as a part of the proton mass, which we call the quantum anomalous energy (QAE). We discuss the QAE origins in both lattice and dimensional regularizations and demonstrate its role as a scheme-and-scale independent component in the mass decomposition. We further argue that QAE role in the proton mass resembles a dynamical Higgs mechanism, in which the anomalous scale symmetry breaking field generates mass scales through its vacuum condensate, as well as its static and dynamical responses to the valence quarks. We demonstrate some of our points in two simpler but closely related quantum field theories, namely the 1+1 dimensional non-linear sigma model in which QAE is non-perturbative and scheme-independent, and QED where the anomalous energy effect is perturbative calculable.

    Comments:
    44 pages, 8 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2105.03974 [pdf]
    NPB(2021)·29 citations
  4. 17

    [Submitted on 18 Apr 2021] (cross-list from quant-ph)

    Incorporating the Coulomb potential into a finite, unitary perturbation theory

    Scott E. Hoffmann

    We have constructed a perturbation theory to treat interactions that can include the Coulomb interaction, describing a physical problem that is often encountered in nuclear physics. The Coulomb part is not treated perturbatively; the exact solutions are employed. The method is an extension of the results presented in Hoffmann (2021 J. Math. Phys. 62 032105). It is designed to calculate phase shifts directly rather than the full form of the wavefunctions in position space. We present formulas that allow calculation of the phase shifts to second order in the perturbation. The phase shift results to second order, for a short-range potential, were compared with the exact solution, where we found an error of third order in the coupling strength. A different model, meant as a simple approximation of nuclear scattering of a proton on Helium-4 and including a Coulomb potential and a spherical well, was constructed to test the theory. The wavepacket scattering formalism of Hoffmann (2017 J. Phy. B: At. Mol. Opt. Phys 50 215302), known to give everywhere finite results, was employed. We found physically acceptable results and a cross section of the correct order of magnitude.

    Comments:
    17 pages, 5 figures, revised
    Subjects:
    Quantum Physics (quant-ph); Nuclear Theory (nucl-th)
    arXiv:
    2105.04362 [pdf]
    J.Math.Phys.(2023)·0 citations
  5. 18

    [Submitted on 10 May 2021] (cross-list from hep-ph)

    Revisiting quark and gluon polarization in the proton at the EIC

    Y. Zhou🇺🇸 · C. Cocuzza🇺🇸 · F. Delcarro🇺🇸 · W. Melnitchouk🇺🇸 · A. Metz🇺🇸 · N. Sato🇺🇸

    We present a comprehensive impact study of future Electron-Ion Collider (EIC) data for parity-conserving and parity-violating polarization asymmetries on quark and gluon helicity distributions in the proton. The study, which is based on the JAM Monte Carlo global QCD analysis framework, explores the role of the extrapolation uncertainty and SU(3) flavor symmetry constraints in the simulated double-spin asymmetry, , at small parton momentum fractions and its effect on the extracted parton polarizations. We find that different assumptions about extrapolations and SU(3) symmetry can have significant consequences for the integrated quark and gluon polarizations, for polarized proton, deuteron and He beams. For the parity-violating asymmetry, , we study the potential impact on the polarized strange quark distribution with different extrapolations of , finding the constraining power to be ultimately limited by the EIC machine luminosity.

    Comments:
    23 pages, 7 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2105.04434 [pdf]
    PRD(2021)·23 citations
  6. 19

    [Submitted on 10 May 2021] (cross-list from nucl-ex)

    The H states studied in the reaction and evidence of extremely correlated character of the H ground state

    E.Yu. Nikolskii🇷🇺 · I.A. Muzalevskii🇷🇺 · A.A. Bezbakh🇷🇺 · V. Chudoba🇷🇺 · S.A. Krupko🇷🇺 · S.G. Belogurov🇷🇺 · D. Biare🇷🇺 · A.S. Fomichev🇷🇺 · E.M. Gazeeva🇷🇺 · A.V. Gorshkov🇷🇺 · L.V. Grigorenko🇷🇺 · G. Kaminski🇷🇺 and 22 other authors

    The extremely neutron-rich system H was studied in the direct H transfer reaction with a MeV secondary He beam. The measured missing mass spectrum shows a broad bump at MeV above the H+ decay threshold. This bump can be interpreted as a broad resonant state in H at MeV. The population cross section of such a presumably -wave state (or may be few overlapping states) in the energy range from 4 to 8 MeV is b/sr in the angular range . The obtained missing mass spectrum is practically free of the H events below 3.5 MeV ( b/sr in the same angular range). The steep rise of the H missing mass spectrum at MeV allows to derive the lower limit for the possible resonant-state energy in H to be MeV. According to the paring energy estimates, such a MeV resonance is a realistic candidate for the H ground state (g.s.). The obtained results confirm that the decay mechanism of the H g.s.\ (located at 2.2 MeV above the H+ threshold) is the "true" (or simultaneous) emission. The resonance energy profiles and the momentum distributions of fragments of the sequential HH(g.s.)+H+ decay were analyzed by the theoretically-updated direct four-body-decay and sequential-emission mechanisms. The measured momentum distributions of the H fragments in the H rest frame indicate very strong "dineutron-type" correlations in the H ground state decay.

    Comments:
    16 pages, 19 figures
    Subjects:
    Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2105.04435 [pdf]
    PRC(2022)·9 citations

Affiliations

first authorsco-authorsvia INSPIRE