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Nuclear Theory·nucl-th

Monday·March 25, 2019

7 papers—3 primary·4 cross-listed

All7Primary3Cross-lists4
  1. 01

    [Submitted on 21 Mar 2019]

    Time-reversed particle-vibration loops and nuclear Gamow-Teller response

    Caroline Robin · Elena Litvinova

    The nuclear response theory for charge-exchange modes in the relativistic particle-vibration coupling approach is extended to include for the first time particle-vibration coupling effects in the ground state of the parent nucleus. In a framework based on the effective meson-nucleon Lagrangian, we investigate the role of such complex ground-state correlations in the description of Gamow-Teller transitions in Zr in both (p,n) and (n,p) channels. The particle-vibration coupling effects are calculated without introducing new parameters. We find that this new correlation mechanism is fully responsible for the appearance of the strength in the (n,p) branch. Comparison of our results to the available experimental data shows a very good agreement up to excitation energies beyond the giant resonance region when taking into account a phenomenological admixture of the isovector spin monopole transitions. The parent-daughter binding-energy differences are also greatly improved by the inclusion of the new correlations.

    Comments:
    5 pages, 5 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1903.09182 [pdf]
    PRL(2019)·47 citations
  2. 02

    [Submitted on 21 Mar 2019]

    Gravitational form factors of light mesons

    Adam Freese🇺🇸 · Ian C. Cloët🇺🇸

    We calculate the gravitational form factors of the pion, sigma meson, and rho meson in the Nambu-Jona-Lasinio (NJL) model of quantum chromodynamics. The canonical energy-momentum tensor (EMT) is used in their derivation, allowing the possibility of an antisymmetric contribution when the hadron has intrinsic spin. We show that the asymmetric graviton vertex arising from the canonical EMT satisfies a simpler Ward-Takahashi identity (WTI) than the symmetric graviton vertex of the Belinfante EMT. The necessity of fully dressing the graviton vertex through the relevant Bethe-Salpeter equation is demonstrated for observing both the WTI and a low-energy pion theorem. Lastly, we calculate static moments of the meson EMT decompositions, obtaining predictions for the meson mass radii. We find light cone mass radii of 0.27 fm for the pion, 0.32 fm for the sigma, and 0.25 fm for the rho. For the pion and rho, these are smaller than the light cone charge radii, respectively 0.51 fm and 0.45 fm, while we have a sigma charge radius of zero. Our light cone pion mass radius agrees with a phenomenological extraction from KEKB data.

    Comments:
    20 pages, 11 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1903.09222 [pdf]
    PRC(2019)·84 citations
  3. 03

    [Submitted on 22 Mar 2019]

    Elastic magnetic electron scattering from deformed nuclei

    P. Sarriguren · D. Merino · O. Moreno · E. Moya de Guerra · D. N. Kadrev · A. N. Antonov · M. K. Gaidarov

    Magnetic form factors corresponding to elastic electron scattering from odd-A nuclei are presented. The calculations are carried out in plane-wave Born approximation. The one-body properties are obtained in a deformed self-consistent mean-field calculation based on a Skyrme HF+BCS method. Collective effects are also included in the cranking approximation. Results on several stable nuclei are compared with the available experimental information. It is shown that a deformed formalism improves the agreement with experiment in deformed nuclei, while reproducing equally well spherical nuclei by taking properly the spherical limit of the deformed model and the effect of nucleon-nucleon correlations. Thus, the capability of the model to describe magnetic form factors is demonstrated. This opens the door to explore also unstable nuclei of particular interest that could be measured in future experiments on electron-radioactive beam colliders.

    Comments:
    13 pages, 9 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1903.09600 [pdf]
    PRC(2019)·15 citations

Affiliations

first authorsco-authorsvia INSPIRE