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Nuclear Theory·nucl-th

Wednesday·December 23, 2020

7 papers—3 primary·4 cross-listed

All7Primary3Cross-lists4
  1. 01

    [Submitted on 21 Dec 2020]

    Towards complete leading-order predictions for neutrinoless double decay

    Vincenzo Cirigliano🇺🇸 · Wouter Dekens🇺🇸 · Jordy de Vries🇺🇸 · Martin Hoferichter🇨🇭 · Emanuele Mereghetti🇺🇸

    The amplitude for the neutrinoless double () decay of the two-neutron system, , constitutes a key building block for nuclear-structure calculations of heavy nuclei employed in large-scale searches. Assuming that the process is mediated by a light-Majorana-neutrino exchange, a systematic analysis in chiral effective field theory shows that already at leading order a contact operator is required to ensure renormalizability. In this work, we develop a method to estimate the numerical value of its coefficient in analogy to the Cottingham formula and validate the result by reproducing the charge-independence-breaking contribution to the nucleon-nucleon scattering lengths. Our central result, while derived in the scheme, is given in terms of the renormalized amplitude , matching to which will allow one to determine the contact-term contribution in regularization schemes employed in nuclear-structure calculations. Our results thus greatly reduce a crucial uncertainty in the interpretation of searches for decay.

    Comments:
    7 pages, 3 figures; journal version. See arXiv:2102.03371 for an extended version
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    2012.11602 [pdf]
    PRL(2021)·103 citations
  2. 02

    [Submitted on 22 Dec 2020]

    Nuclear charge-exchange excitations based on relativistic density-dependent point-coupling model

    D. Vale · Y. F. Niu · N. Paar

    Spin-isospin transitions in nuclei away from the valley of stability are essential for the description of astrophysically relevant weak interaction processes. While they remain mainly beyond the reach of experiment, theoretical modeling provides important insight into their properties. In order to describe the spin-isospin response,vcthe proton-neutron relativistic quasiparticle random phase approximation (PN-RQRPA) is formulated using the relativistic density-dependent point coupling interaction, and separable pairing interaction in both the and pairing channels. By implementing recently established DD-PCX interaction with improved isovector properties relevant for the description of nuclei with neutron-to-proton number asymmetry, the isobaric analog resonances (IAR) and Gamow-Teller resonances (GTR) have been investigated. In contrast to other models that usually underestimate the IAR excitation energies in Sn isotope chain, the present model accurately reproduces the experimental data, while the GTR properties depend on the isoscalar pairing interaction strength. This framework provides not only an improved description of the spin-isospin response in nuclei, but it also allows future large scale calculations of charge-exchange excitations and weak interaction processes in stellar environment.

    Comments:
    40 pages, 6 figures, revised version
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2012.11977 [pdf]
    PRC(2021)·22 citations
  3. 03

    [Submitted on 22 Dec 2020]

    Structure of double pionic atoms

    Akari Tani🇯🇵 · Natsumi Ikeno🇯🇵 · Daisuke Jido🇯🇵 · Hideko Nagahiro🇯🇵 · Hiroyuki Fujioka🇯🇵 · Kenta Itahashi🇯🇵 · Satoru Hirenzaki🇯🇵

    We study theoretically the structure of double pionic atoms, in which two negatively charged pions () are bound in the atomic orbits. The double pionic atom is considered to be an interesting system from the point of view of the multi bosonic systems. In addition, it could be possible to deduce valuable information on the isospin interaction and the pion-nucleus strong interaction. In this paper, we take into account the strong and electromagnetic interactions, and evaluate the effects on the binding energies by perturbation theory for the double pionic atoms in heavy nuclei. We investigate several combinations of two pionic states and find that the order of magnitude of the energy shifts due to the interaction is around 10 keV for the strong interaction and around 100 keV for the electromagnetic interaction for the ground states.

    Comments:
    16 pages, 6 figures, 5 tables
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2012.12236 [pdf]
    PTEP(2021)·4 citations

Affiliations

first authorsco-authorsvia INSPIRE