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Nuclear Theory·nucl-th

Wednesday·July 14, 2021

5 papers—3 primary·2 cross-listed

All5Primary3Cross-lists2
  1. 01

    [Submitted on 13 Jul 2021]

    Angular momentum projection in the deformed relativistic Hartree-Bogoliubov theory in continuum

    Xiang-Xiang Sun · Shan-Gui Zhou

    The angular momentum projection (AMP) method is implemented in the deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc) with the point-coupling density functional. The wave functions of angular momentum projected states are expanded in terms of the Dirac Woods-Saxon (WS) basis, providing a proper description of the asymptotic behavior of the wave functions for weakly bound nuclei. The contribution of continuum induced by the pairing is considered by treating the pairing correlation with the Bogoliubov transformation. We present the formulae and numerical checks for the DRHBc+AMP approach and use it to study low-lying excited states of weakly bound deformed nuclei. Our calculations show that neutron-rich magnesium isotopes Mg are all well deformed nuclei. The low-lying excited states of these three nuclei are obtained by performing the AMP on the mean-field ground-states. The ground-state rotational bands of Mg are reproduced reasonably well by using this new DRHBc+AMP approach with the density functional PC-F1.

    Comments:
    18 pages, 11 figures, 3 tables
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2107.05925 [pdf]
    PRC(2021)·40 citations
  2. 02

    [Submitted on 13 Jul 2021]

    Many-body theory for quasiparticle states in superfluid fermionic systems

    Elena Litvinova · Yinu Zhang

    We present a formalism for the fermionic quasiparticle propagator in a superfluid fermionic system. Starting from a general many-body hamiltonian confined by the two-body instantaneous interaction, the equation of motion for the fermionic propagator is obtained in the Dyson form. Before making any approximation, the interaction kernel is found to be decomposed into the static and dynamical (time-dependent) contributions, while the latter translates to the energy-dependent and the former maps to the energy-independent terms in the energy domain. The three-fermion correlation function being the heart of the dynamical part of the kernel is factorized into the two-fermion and one-fermion ones. With the relaxed particle number constraint, the normal propagator is coupled to the abnormal one via both the static and dynamical kernels, that is formalized by introducing the generalized quasiparticle propagator of the Gor'kov type. The dynamical kernel in the factorized form is associated with the quasiparticle-vibration coupling (QVC) with the vibrations unifying both the normal and pairing phonons. The QVC vertices are related to the variations of the Hamiltonian of the Bogoliubov quasiparticles, which can be obtained by the finite amplitude method.

    Comments:
    Article: 21 pages, 3 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2107.06199 [pdf]
    PRC(2021)·10 citations
  3. 03

    [Submitted on 13 Jul 2021]

    Constraining Neutron-Star Matter with Microscopic and Macroscopic Collisions

    S. Huth · P. T. H. Pang · I. Tews · T. Dietrich · A. Le Fèvre · A. Schwenk · W. Trautmann · K. Agarwal · M. Bulla · M. W. Coughlin · C. Van Den Broeck

    Interpreting high-energy, astrophysical phenomena, such as supernova explosions or neutron-star collisions, requires a robust understanding of matter at supranuclear densities. However, our knowledge about dense matter explored in the cores of neutron stars remains limited. Fortunately, dense matter is not only probed in astrophysical observations, but also in terrestrial heavy-ion collision experiments. In this work, we use Bayesian inference to combine data from astrophysical multi-messenger observations of neutron stars and from heavy-ion collisions of gold nuclei at relativistic energies with microscopic nuclear theory calculations to improve our understanding of dense matter. We find that the inclusion of heavy-ion collision data indicates an increase in the pressure in dense matter relative to previous analyses, shifting neutron-star radii towards larger values, consistent with recent NICER observations. Our findings show that constraints from heavy-ion collision experiments show a remarkable consistency with multi-messenger observations and provide complementary information on nuclear matter at intermediate densities. This work combines nuclear theory, nuclear experiment, and astrophysical observations, and shows how joint analyses can shed light on the properties of neutron-rich supranuclear matter over the density range probed in neutron stars.

    Comments:
    7 pages, 2 figures, Supplemental Material, minor changes
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); General Relativity and Quantum Cosmology (gr-qc); Nuclear Experiment (nucl-ex)
    arXiv:
    2107.06229 [pdf]
    Nature(2022)·388 citations
  4. 04

    [Submitted on 13 Jul 2021] (cross-list from physics.comp-ph)

    QTRAJ 1.0: A Lindblad equation solver for heavy-quarkonium dynamics

    Hisham Ba Omar🇺🇸 · Miguel Ángel Escobedo🇪🇸 · Ajaharul Islam🇺🇸 · Michael Strickland🇺🇸 · Sabin Thapa🇺🇸 · Peter Vander Griend🇩🇪 · Johannes Heinrich Weber🇩🇪

    We introduce an open-source package called QTraj that solves the Lindblad equation for heavy-quarkonium dynamics using the quantum trajectories algorithm. The package allows users to simulate the suppression of heavy-quarkonium states using externally-supplied input from 3+1D hydrodynamics simulations. The code uses a split-step pseudo-spectral method for updating the wave-function between jumps, which is implemented using the open-source multi-threaded FFTW3 package. This allows one to have manifestly unitary evolution when using real-valued potentials. In this paper, we provide detailed documentation of QTraj 1.0, installation instructions, and present various tests and benchmarks of the code.

    Comments:
    35 pages, 10 figures; v2 - minor typos fixed; published version
    Subjects:
    Computational Physics (physics.comp-ph); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
    arXiv:
    2107.06147 [pdf]
    Comput.Phys.Commun.(2022)·39 citations
  5. 05

    [Submitted on 13 Jul 2021] (cross-list from hep-ph)

    Bottomonium production in heavy-ion collisions using quantum trajectories: Differential observables and momentum anisotropy

    Nora Brambilla🇩🇪 · Miguel Ángel Escobedo🇪🇸 · Michael Strickland🇺🇸 · Antonio Vairo🇩🇪 · Peter Vander Griend🇩🇪 · Johannes Heinrich Weber🇺🇸

    We report predictions for the suppression and elliptic flow of the , , and as a function of centrality and transverse momentum in ultra-relativistic heavy-ion collisions. We obtain our predictions by numerically solving a Lindblad equation for the evolution of the heavy-quarkonium reduced density matrix derived using potential nonrelativistic QCD and the formalism of open quantum systems. To numerically solve the Lindblad equation, we make use of a stochastic unraveling called the quantum trajectories algorithm. This unraveling allows us to solve the Lindblad evolution equation efficiently on large lattices with no angular momentum cutoff. The resulting evolution describes the full 3D quantum and non-abelian evolution of the reduced density matrix for bottomonium states. We expand upon our previous work by treating differential observables and elliptic flow; this is made possible by a newly implemented Monte-Carlo sampling of physical trajectories. Our final results are compared to experimental data collected in TeV Pb-Pb collisions by the ALICE, ATLAS, and CMS collaborations.

    Comments:
    14 pages, 11 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th); Computational Physics (physics.comp-ph)
    arXiv:
    2107.06222 [pdf]
    PRD(2021)·71 citations

Affiliations

first authorsco-authorsvia INSPIRE