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Nuclear Theory·nucl-th

Friday·September 18, 2020

8 papers—4 primary·4 cross-listed

All8Primary4Cross-lists4
  1. 01

    [Submitted on 17 Sept 2020]

    Covariant density functional theory for nuclear chirality in Nd

    J. Peng🇨🇳 · Q. B. Chen🇩🇪

    The three-dimensional tilted axis cranking covariant density functional theory (3D-TAC CDFT) is used to study the chiral modes in Nd. By modeling the motion of the nucleus in rotating mean field as the interplay between the single-particle motions of several valence particle(s) and hole(s) and the collective motion of a core-like part, a classical Routhian is extracted. This classical Routhian gives qualitative agreement with the 3D-TAC CDFT result for the critical frequency corresponding to the transition from planar to aplanar rotation. Based on this investigation a possible understanding of tilted rotation appearing in a microscopic theory is provided.

    Comments:
    6 pages, 4 figures
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2009.08075 [pdf]
    PLB(2020)·13 citations
  2. 02

    [Submitted on 17 Sept 2020]

    Detailed spectrum calculations of Pb for new physics searches in liquid Xenon

    Leendert Hayen🇺🇸 · Stefano Simonucci🇮🇹 · Simone Taioli🇮🇹

    We present a critical assessment of the calculation and uncertainty of the Pb Bi ground state to ground state decay, the dominant source of background in liquid Xenon dark matter detectors, down to below 1 keV. We consider contributions from atomic exchange effects, nuclear structure and radiative corrections. For each of these, we find changes much larger than previously estimated uncertainties and discuss shortcomings of the original calculation. Specifically, through the use of a self-consistent Dirac-Hartree-Fock-Slater calculation, we find that the atomic exchange effect increases the predicted flux by at 1 keV relative to previous exchange calculations. Further, using a shell model calculation of the nuclear structure contribution to the shape factor, we find a strong disagreement with the allowed shape factor and discuss several sources of uncertainty. In the 1-200 keV window, the predicted flux is up to 20 lower. Finally, we discuss omissions and detector effects in previously used QED radiative corrections, and find small changes in the slope at the MeV level, up to in magnitude due to omissions in corrections and uncertainty from the neglect of as of yet unavailable higher-order contributions. Combined, these give rise to an increase of at least a factor 2 of the uncertainty in the 1-200 keV window. We comment on possible experimental schemes of measuring this and related transitions.

    Comments:
    9 pages, 4 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    2009.08303 [pdf]
    6 citations
  3. 03

    [Submitted on 17 Sept 2020]

    Pionless Effective Field Theory Evaluation of Nuclear Polarizability in Muonic Deuterium

    Samuel B. Emmons🇺🇸 · Chen Ji🇨🇳 · Lucas Platter🇺🇸

    We calculate the longitudinal structure function of the deuteron up through next-to-next-to-leading order in the framework of pionless effective field theory. We use these results to compute the two-photon polarizability contribution to Lamb shift in muonic deuterium, which can be utilized to extract the nuclear charge radius of the deuteron. We present analytical expressions order-by-order for the relevant transition matrix elements and the longitudinal structure function, and we give numerical results for the corresponding contributions to the Lamb shift. We also discuss the impact of relativistic and other higher-order effects. We find agreement with previous calculations and explain the accuracy of our calculation.

    Comments:
    26 pages, 6 figures, 1 table
    Subjects:
    Nuclear Theory (nucl-th); Atomic Physics (physics.atom-ph)
    arXiv:
    2009.08347 [pdf]
    J.Phys.G(2021)·10 citations
  4. 04

    [Submitted on 17 Sept 2020]

    A global microscopic description of nucleon-nucleus scattering with quantified uncertainties

    T. R. Whitehead · Y. Lim · J. W. Holt

    We develop for the first time a microscopic global nucleon-nucleus optical potential with quantified uncertainties suitable for analyzing nuclear reaction experiments at next-generation rare-isotope beam facilities. Within the improved local density approximation and without any adjustable parameters, we begin by computing proton-nucleus and neutron-nucleus optical potentials from a set of five nuclear forces from chiral effective field theory for 1800 target nuclei in the mass range 12 A 242 for energies between 0 MeV E 150 MeV. We then parameterize a global optical potential for each chiral force that depends smoothly on the projectile energy as well as the target nucleus mass number and isospin asymmetry. Uncertainty bands for elastic scattering observables are generated from a full covariance analysis of the parameters entering in the description of our global optical potential and benchmarked against existing experimental data for stable target nuclei. Since our approach is purely microscopic, we anticipate a similar quality of the model for nucleon scattering on unstable isotopes.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2009.08436 [pdf]
    PRL(2021)·49 citations

Affiliations

first authorsco-authorsvia INSPIRE