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Nuclear Theory·nucl-th

Thursday·January 10, 2019

2 papers—1 primary·1 cross-listed

All2Primary1Cross-lists1
  1. 01

    [Submitted on 9 Jan 2019]

    Spectral functions of nucleon form factors: Three-pion continua at low energies

    N. Kaiser🇩🇪 · E. Passemar🇺🇸

    We study the imaginary parts of the isoscalar electromagnetic and isovector axial form factors of the nucleon close to the -threshold in covariant baryon chiral perturbation theory. At the two-loop level, the contributions arising from leading and next-to-leading order chiral -vertices, as well as pion-induced excitations of virtual -isobars, are calculated. It is found that the heavy baryon treatment overestimates substantially these -continua. From a phenomenological analysis, that includes the narrow -resonance or the broad -resonance, one can recognize small windows near threshold, where chiral -dynamics prevails. However, in the case of the isoscalar electromagnetic form factors , the radiative correction provided by the -intermediate state turns out to be of similar size.

    Comments:
    12 pages, 9 figures, accepted for publication in Eur. Phys. J. A
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1901.02865 [pdf]
    EPJA(2019)·15 citations
  2. 02

    [Submitted on 9 Jan 2019] (cross-list from physics.atom-ph)

    Few-body quantum method in a -dimensional space

    E. Garrido🇪🇸 · A.S. Jensen🇩🇰 · R. Álvarez-Rodríguez🇪🇸

    In this work we investigate the continuous confinement of quantum systems from three to two dimensions. Two different methods will be used and related. In the first one the confinement is achieved by putting the system under the effect of an external field. This method is conceptually simple, although, due to the presence of the external field, its numerical implementation can become rather cumbersome, especially when the system is highly confined. In the second method the external field is not used, and it simply considers the spatial dimension as a parameter that changes continuously between the ordinary integer values. In this way the numerical effort is absorbed in a modified strength of the centrifugal barrier. Then the technique required to obtain the wave function of the confined system is precisely the same as needed in ordinary three dimensional calculations without any confinement potential. The case of a two-body system squeezed from three to two dimensions is considered, and used to provide a translation between all the quantities in the two methods. Finally we point out perspectives for applications on more particles, different spatial dimensions, and other confinement potentials.

    Comments:
    To be published in Physics Letters A
    Subjects:
    Atomic Physics (physics.atom-ph); Nuclear Theory (nucl-th); physics.atm-clus (physics.atm-clus)
    arXiv:
    1901.02667 [pdf]
    PLA(2019)·12 citations

Affiliations

first authorsco-authorsvia INSPIRE