PaperPanorama

Nuclear Theory·nucl-th

Monday·January 12, 2015

8 papers2 primary·6 cross-listed

  1. 01

    [Submitted on 8 Jan 2015]

    Electromagnetic and neutral-weak response functions of 4He and 12C

    A. Lovato🇺🇸 · S. Gandolfi🇺🇸 · J. Carlson🇺🇸 · Steven C. Pieper🇺🇸 · R. Schiavilla🇺🇸

    Ab initio calculations of the quasi-elastic electromagnetic and neutral-weak response functions of 4He and 12C are carried out for the first time. They are based on a realistic approach to nuclear dynamics, in which the strong interactions are described by two- and three-nucleon potentials and the electroweak interactions with external fields include one- and two-body terms. The Green's function Monte Carlo method is used to calculate directly the Laplace transforms of the response functions, and maximum-entropy techniques are employed to invert the resulting imaginary-time correlation functions with associated statistical errors. The theoretical results, confirmed by experiment in the electromagnetic case, show that two-body currents generate excess transverse strength from threshold to the quasi-elastic to the dip region and beyond. These findings challenge the conventional picture of quasi-elastic inclusive scattering as being largely dominated by single-nucleon knockout processes.

    Comments:
    6 pages, 3 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1501.01981 [pdf]
    PRC(2015)·91 citations
  2. 02

    [Submitted on 9 Jan 2015]

    Problems with meson spectroscopy involving perturbative loop corrections

    K. P. Khemchandani🇧🇷 · Eef Van Beveren🇵🇹 · George Rupp🇵🇹

    In this talk we review the limitations of including meson loops as perturbative corrections in a solvable quark model. We first discuss meson-meson scattering within a formalism which treats confined quark pairs and mesons on an equal footing. The interaction between the mesons proceeds through -channel meson-exchange diagrams. Next, we develop a perturbative expansion of the model, and show that the resonance poles found in such a treatment, even by accounting for contributions up to fourth order, do not coincide with those obtained with the full model. We conclude that the resonance predictions based on perturbative approximations in quark models are not reliable, especially in those cases where the coupling to the scattering channels is large.

    Comments:
    Conference proceedings for EEF70, Workshop on Unquenched Hadron Spectroscopy:Non-Perturbative Models and Methods of QCD vs. Experiment
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1501.02257 [pdf]
    Acta Phys.Polon.Supp.(2015)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE