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Nuclear Theory·nucl-th

Monday·May 23, 2022

10 papers—5 primary·5 cross-listed

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  1. 01

    [Submitted on 20 May 2022]

    The proton structure in and out of muonic hydrogen

    Aldo Antognini (PSI, ETH Zürich)🇨🇭 · Franziska Hagelstein (JGU Mainz, PSI)🇨🇭 · Vladimir Pascalutsa (JGU Mainz)🇩🇪

    Laser spectroscopy of muonic atoms has been recently used to probe properties of light nuclei with unprecedented precision. We introduce nuclear effects in hydrogen-like atoms, nucleon structure quantities (form factors, structure functions, polarizabilities) and their effects in the Lamb shift and hyperfine splitting (HFS) of muonic hydrogen (H). Updated theory predictions for the Lamb shift and HFS in H are presented. We review the challenges of the ongoing effort to measure the ground-state HFS in H and its impact on our understanding of the nucleon spin structure. To narrow down this search, we present a novel theory prediction obtained by scaling the measured HFS in hydrogen leveraging radiative corrections. We also summarize recent developments in the spectroscopy of simple atomic and molecular systems and emphasize how they allow for precise determinations of fundamental constants, bound-state QED tests and New Physics searches.

    Comments:
    48 pages; 11 figures; 4 tables; final version with extended Supplement; posted with permission from the Annual Review of Nuclear and Particle Science, Volume 72 by Annual Reviews, http://www.annualreviews.org
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Atomic Physics (physics.atom-ph)
    arXiv:
    2205.10076 [pdf]
    Ann.Rev.Nucl.Part.Sci.(2022)·70 citations
  2. 02

    [Submitted on 20 May 2022]

    Least-square approach for singular value decompositions of scattering problems

    A. Tichai🇩🇪 · P. Arthuis🇩🇪 · K. Hebeler🇩🇪 · M. Heinz🇩🇪 · J. Hoppe🇩🇪 · A. Schwenk🇩🇪 · L. Zurek🇩🇪

    It was recently observed that chiral two-body interactions can be efficiently represented using matrix factorization techniques such as the singular value decomposition. However, the exploitation of these low-rank structures in a few- or many-body framework is nontrivial and requires reformulations that explicitly utilize the decomposition format. In this work, we present a general least-square approach that is applicable to different few- and many-body frameworks and allows for an efficient reduction to a low number of singular values in the least-square iteration. We verify the feasibility of the least-square approach by solving the Lippmann-Schwinger equation in factorized form. The resulting low-rank approximations of the matrix are found to fully capture scattering observables. Potential applications of the least-square approach to other frameworks with the goal of employing tensor factorization techniques are discussed.

    Comments:
    8 pages, 4 figures, 1 table, version accepted at Phys. Rev. C
    Subjects:
    Nuclear Theory (nucl-th); Strongly Correlated Electrons (cond-mat.str-el)
    arXiv:
    2205.10087 [pdf]
    PRC(2022)·9 citations
  3. 03

    [Submitted on 20 May 2022]

    In-medium effects in meson production in heavy-ion collisions from subthreshold to relativistic energies

    Taesoo Song🇩🇪 · Joerg Aichelin🇫🇷 · Elena Bratkovskaya🇩🇪

    We investigate the hidden strange meson production in heavy-ion collisions from subthreshold ( A GeV) to relativistic ( A TeV) energies as well as its coupling to the open strange mesons (kaons, antikaons) and their productions. Our study is based on the off-shell microscopic Parton-Hadron-String Dynamics (PHSD) transport approach which is applicable for the dynamical description of strongly interacting hadronic and partonic degrees-of-freedom created in heavy-ion collisions. Implementing novel meson-baryon and meson-hyperon production channels for mesons, calculated within a T-matrix coupled channel approach based on the extended SU(6) chiral effective Lagrangian model, along with the collisional broadening of the -meson in-medium spectral function, we find a substantial enhancement of meson production in heavy-ion collisions, especially at sub- and near-thresholds. This allows to describe the experimentally observed strong enhancement of the ratio at low energies without including hypothetical decays of heavy baryonic resonances to as in alternative approaches. Moreover, we show that in spite of a stronger contribution from enhanced to production, the majority of the experimental data for different A+A systems at low energies favor the scenario with in-medium modifications of the kaon and antikaon properties in the hot and dense environment. Moreover, we study the influence of the final state interactions of mesons on the reconstruction of 's by the by invariant mass method.

    Comments:
    24 pages, 22 figures
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2205.10251 [pdf]
    PRC(2022)·22 citations
  4. 04

    [Submitted on 20 May 2022]

    Relativistic mean-field theories for neutron-star physics based on chiral effective field theory

    Mark G. Alford🇺🇸 · Liam Brodie🇺🇸 · Alexander Haber🇺🇸 · Ingo Tews🇺🇸

    We describe and implement a procedure for determining the couplings of a Relativistic Mean-Field Theory (RMFT) that is optimized for application to neutron star phenomenology. In the standard RMFT approach, the couplings are constrained by comparing the theory's predictions for symmetric matter at saturation density with measured nuclear properties. The theory is then applied to neutron stars which consist of neutron-rich matter at densities ranging up to several times saturation density, which allows for additional astrophysical constraints. In our approach, rather than using the RMFT to extrapolate from symmetric to neutron-rich matter and from finite-sized nuclei to uniform matter, we fit the RMFT to properties of uniform pure neutron matter obtained from chiral effective field theory. Chiral effective field theory incorporates the experimental data for nuclei in the framework of a controlled expansion for nuclear forces valid at nuclear densities and enables us to account for theoretical uncertainties when fitting the RMFT. We construct four simple RMFTs that span the uncertainties provided by chiral effective field theory for neutron matter, and are consistent with current astrophysical constraints on the equation of state. Our RMFTs can be used to model the properties of neutron-rich matter across the vast range of densities and temperatures encountered in neutron stars and their mergers.

    Comments:
    V2: Minor corrections, version published in PRC. 12 pages and 5 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2205.10283 [pdf]
    PRC(2022)·73 citations
  5. 05

    [Submitted on 20 May 2022]

    Numerical Simulation of Shell Model Single Particle Energy States using Matrix Numerov Method in Gnumeric Worksheet

    Shikha Awasthi · Aditi Sharma · Swapna Gora · O.S.K.S. Sastri

    Single particle energy states as described by nuclear shell model are obtained for doubly magic nuclei using Gnumeric worksheet environment. Numerov method rephrased in matrix form is utilised to solve time-independent Schrodinger equation (TISE) within mean-field approximation, described by Woods-Saxon (WS) potential along with spin-orbit term, to obtain the single particle energies for both neutron and proton states. The WS model parameters are chosen from previous simulation results performed using matrix methods technique involving sine basis, where optimization was done w.r.t available experimental single particle energies for 208Pb and 48Ca. In this paper, only the algorithm parameters, step size h and matrix size N are optimized to obtain the expected energy level sequence obtained using matrix methods. An attempt is made, by incorporating this tool within the framework of guided inquiry strategy (a constructivist approach to learning), to actively engage the students in assigning appropriate spin-parity configurations for ground states of nuclei neighbouring the doubly magic ones. It has been observed that the ground state configurations could be better predicted when energy level sequences are known for all nuclei as compared to what is usually obtained from that of 208Pb alone.

    Comments:
    17 pages, 2 Figures, 4 Tables
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2205.10335 [pdf]
    0 citations

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