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Nuclear Theory·nucl-th

Wednesday·August 16, 2023

7 papers—4 primary·3 cross-listed

All7Primary4Cross-lists3
  1. 01

    [Submitted on 15 Aug 2023]

    On the dynamical kernels of fermionic equations of motion in strongly-correlated media

    Elena Litvinova🇺🇸

    Two-point fermionic propagators in strongly-correlated media are considered with an emphasis on the dynamical interaction kernels of their equations of motion (EOM). With the many-body Hamiltonian confined by a two-body interaction, the EOMs for the two-point fermionic propagators acquire the Dyson form and, before taking any approximation, the interaction kernels decompose into the static and dynamical (time-dependent) contributions. The latter translate to the energy-dependent and the former map to the energy-independent terms in the energy domain. We dwell particularly on the energy-dependent terms, which generate long-range correlations while making feedback on their short-range static counterparts. The origin, forms, and various approximations for the dynamical kernels of one-fermion and two-fermion propagators, most relevant in the intermediate-coupling regime, are discussed. Applications to the electromagnetic dipole response of Ni and low-energy quadrupole response of Sn are presented.

    Comments:
    Article: 20 pages, 10 figures. Contribution to the EPJ A Topical Collection devoted to the legacy of Peter Schuck
    Subjects:
    Nuclear Theory (nucl-th); cond-mat.other (cond-mat.other); Nuclear Experiment (nucl-ex)
    arXiv:
    2308.07574 [pdf]
    EPJA(2023)·13 citations
  2. 02

    [Submitted on 15 Aug 2023]

    Open Quantum Systems with Kadanoff-Baym Equations

    Tim Neidig🇩🇪 · Jan Rais🇩🇪 · Marcus Bleicher🇩🇪 · Hendrik van Hees🇩🇪 · Carsten Greiner🇩🇪

    We study the temporal evolution of quantum mechanical fermionic particles exhibiting one bound state within a one-dimensional attractive square-well potential in a heat bath of bosonic particles. For this open quantum system we formulate the non-equilibrium Kadanoff-Baym equations for the system particles by taking the interactions to be elastic 2-2 scatterings with the heat-bath particles. The corresponding spatially imhomogeneous integro-differential equations for the one-particle Greens's function are solved numerically. We demonstrate how the system particles equilibrate and thermalize with the heat bath and how the off-diagonal elements of the density matrix, expressed in the one-particle energy eigenbasis, decohere, so that only the diagonal entries, i.e. the occupation numbers, survive. In addition, the time evolution of the (retarded) Green's function also determines the spectral properties of the various one-particle quantum states.

    Comments:
    6 pages, 3 figures, accepted in Physics Letters B
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Quantum Physics (quant-ph)
    arXiv:
    2308.07659 [pdf]
    PLB(2024)·9 citations
  3. 03

    [Submitted on 15 Aug 2023]

    Paring correlations within the micro-macroscopic approach for the level density

    A.G.Magner · A.I.Sanzhur · S.N.Fedotkin · A.I.Levon · U.V.Grygoriev · S.Shlomo

    Level density is calculated for the two-component close- and open-shell nuclei with a given energy , and neutron and proton numbers, taking into account pairing effects within the microscopic-macroscopic approach (MMA). These analytical calculations have been carried out by using the semiclassical statistical mean-field approximations beyond the saddle-point method of the Fermi gas model in a low excitation-energies range. The level density , obtained as function of the system entropy , depends essentially on the condensation energy through the excitation energy in super-fluid nuclei. The simplest super-fluid approach, based on the BCS theory, accounts for a smooth temperature dependence of the pairing gap due to particle number fluctuations. Taking into account the pairing effects in magic or semi-magic nuclei, excited below neutron resonances, one finds a notable pairing phase transition.Pairing correlations sometimes improve significantly the comparison with experimental data.

    Comments:
    8 pages, 2 figures, 2 tables
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2308.07784 [pdf]
    EPJA(2024)·3 citations
  4. 04

    [Submitted on 15 Aug 2023]

    and mesons in nuclear matter and nuclei

    J.J Cobos-Martinez🇲🇽 · Kazuo Tsushima🇧🇷

    We present updated and extended results for the - and -nucleus bound state energies, obtained by solving the Schrödinger and Klein-Gordon equations with complex optical potentials, for a wide range of nuclei. The and nuclear potentials are obtained in the local density approximation from the mass shift of these mesons in nuclear matter, which is calculated within the quark-meson coupling model. Our results show that the and mesons are expected to form mesic nuclei with all the nuclei considered. However, the signal for the formation of the - and -mesic nuclei may be difficult to identify experimentally due to possible large widths.

    Comments:
    11 pages, 4 figures, 6 tables
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2308.07836 [pdf]
    PRC(2024)·12 citations
  5. 05

    [Submitted on 14 Aug 2023] (cross-list from hep-ph)

    Global analysis of polarized DIS & SIDIS data with improved small- helicity evolution

    Daniel Adamiak🇺🇸 · Nicholas Baldonado🇺🇸 · Yuri V. Kovchegov🇺🇸 · W. Melnitchouk🇺🇸 · Daniel Pitonyak🇺🇸 · Nobuo Sato🇺🇸 · Matthew D. Sievert🇺🇸 · Andrey Tarasov🇺🇸 · Yossathorn Tawabutr🇫🇮

    We analyze the world polarized deep-inelastic scattering (DIS) and semi-inclusive DIS (SIDIS) data at low values of , using small- evolution equations for the flavor singlet and nonsinglet helicity parton distribution functions (hPDFs). The hPDFs for quarks, antiquarks, and gluons are extracted and evolved to lower values of to make predictions for the future Electron-Ion Collider (EIC). We improve on our earlier work by employing the more realistic large- limit of the revised small- helicity evolution, and incorporating running coupling corrections along with SIDIS data into the fit. We find an anti-correlation between the signs of the gluon and -even quark hPDFs as well as the structure function. While the existing low- polarized DIS and SIDIS data are insufficient to constrain the initial conditions for the polarized dipole amplitudes in the helicity evolution equations, future EIC data will allow more precise predictions for hPDFs and the structure function for values beyond those probed at the EIC. Using the obtained hPDFs, we discuss the contributions to the proton spin from quark and gluon spins at small .

    Comments:
    42 Pages, 21 Figures,
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
    arXiv:
    2308.07461 [pdf]
    PRD(2023)·32 citations
  6. 06

    [Submitted on 14 Aug 2023] (cross-list from astro-ph.CO)

    The Scale Invariant Vacuum Paradigm: Main Results plus the Current BBNS Progress

    Vesselin G. Gueorguiev · Andre Maeder

    We summarize the main results within the Scale Invariant Vacuum (SIV) paradigm as related to the Weyl Integrable Geometry (WIG) as an extension to the standard Einstein General Relativity (EGR). After a short sketch of the mathematical framework, the main results until 2023 [1] are highlighted in relation to: the inflation within the SIV [2], the growth of the density fluctuations [3], the application of the SIV to scale-invariant dynamics of galaxies, MOND, dark matter, and the dwarf spheroidals [4],and the most recent results on the BBNS light-elements' abundances within the SIV [5]. Keywords: cosmology: theory, dark matter, dark energy, inflation, BBNS; galaxies: formation, rotation; Weyl integrable geometry; Dirac co-calculus.

    Comments:
    10 pages, 3 figures, 2 tables; Comments and constructive suggestions are highly welcome. Presentation slides are available at ResearchGate.net via the link www.researchgate.net/publication/362388677; Contribution to the Relativity Theory conference at the Bauman Moscow State Technical University, Moscow, 4 July, 2023 (PIRT-2023 https://pirt.bmstu.ru/en/home-en/);. arXiv admin note: substantial text overlap with arXiv:2202.08412
    Subjects:
    Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
    arXiv:
    2308.07483 [pdf]
    0 citations
  7. 07

    [Submitted on 15 Aug 2023] (cross-list from hep-ph)

    New insights into the nature of the and resonances away from the SU(3) limit

    Feng-Kun Guo🇨🇳 · Yuki Kamiya🇩🇪 · Maxim Mai🇩🇪 · Ulf-G. Meißner🇩🇪

    Starting from the SU(3) limit, we consider the nature of the dynamically generated resonances , and as the pion and kaon masses are tuned to their physical values. We show that the accidental symmetry of the two octets due to the leading order Weinberg-Tomozawa term is broken by the next-to-leading order terms. Most interestingly, we observe an interchange of the two trajectories of the and the away from the SU(3) limit at next-to-leading order. This remarkable phenomenon can be investigated using lattice QCD calculations that start from the SU(3) limit.

    Comments:
    We have updated the notation compared to the journal version. No calculation or results are changed by this, 11 pages, 4 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
    arXiv:
    2308.07658 [pdf]
    PLB(2023)·34 citations

Affiliations

first authorsco-authorsvia INSPIRE