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Nuclear Theory·nucl-th

Wednesday·April 15, 2020

9 papers—3 primary·6 cross-listed

All9Primary3Cross-lists6
  1. 04

    [Submitted on 13 Apr 2020] (cross-list from hep-ph)

    Asymptotic behavior of meson transition form factors

    Martin Hoferichter🇨🇭 · Peter Stoffer🇺🇸

    One of the open issues in evaluations of the contribution from hadronic light-by-light scattering to the anomalous magnetic moment of the muon concerns the role of heavier scalar, axial-vector, and tensor-meson intermediate states. The coupling of axial vectors to virtual photons is suppressed for small virtualities by the Landau-Yang theorem, but otherwise there are few rigorous constraints on the corresponding form factors. In this paper, we first derive the Lorentz decomposition of the two-photon matrix elements into scalar functions following the general recipe by Bardeen, Tung, and Tarrach. Based on this decomposition, we then calculate the asymptotic behavior of the meson transition form factors from a light-cone expansion in analogy to the asymptotic limits for the pseudoscalar transition form factor derived by Brodsky and Lepage. Finally, we compare our results to existing data as well as previous models employed in the literature.

    Comments:
    29 pages, 4 figures; journal version
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
    arXiv:
    2004.06127 [pdf]
    JHEP(2020)·103 citations
  2. 05

    [Submitted on 14 Apr 2020] (cross-list from nucl-ex)

    Scission configuration of U from yields and kinetic information of fission fragments

    D. Ramos🇫🇷 · M. Caamano🇪🇸 · A. Lemasson🇫🇷 · M. Rejmund🇫🇷 · L. Audouin🇫🇷 · H. Alvarez-Pol🇪🇸 · J.D. Frankland🇫🇷 · B. Fernandez-Dominguez🇪🇸 · E. Galiana-Baldo🇪🇸 · J. Piot🇫🇷 · D. Ackermann🇫🇷 · S. Biswas🇫🇷 and 16 other authors

    The simultaneous measurement of the isotopic fission-fragment yields and fission-fragment velocities of U has been performed for the first time. The U fissioning system was produced in one-neutron transfer reactions between a U beam at 5.88 MeV/nucleon and a Be target. The combination of inverse kinematics at low energy and the use of the VAMOS++ spectrometer at the GANIL facility allows the isotopic identification of the full fission-fragment distribution and their velocity in the reference frame of the fissioning system. The proton and neutron content of the fragments at scission, their total kinetic and total excitation energy, as well as the neutron multiplicity were determined. Information from the scission point configuration is obtained from these observables and the correlation between them. The role of the octupole-deformed proton and neutron shells in the fission-fragment production is discussed.

    Comments:
    8 pages, 7 figures
    Subjects:
    Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2004.06346 [pdf]
    PRC(2020)·15 citations
  3. 06

    [Submitted on 14 Apr 2020] (cross-list from hep-ph)

    Particle productions and anisotropic flows from the AMPT model for Cu+Au collisions at GeV

    Yuncun He🇨🇳 · Zi-Wei Lin🇺🇸

    We use the string melting version of a multi-phase transport (AMPT) model to study Cu+Au collisions at GeV. The rapidity distributions of identified hadrons show asymmetric dependences on rapidity. In addition, elliptic and triangular flows at mid-rapidity from the AMPT model for pions, kaons, and protons agree reasonably with the experimental data up to GeV. We then investigate the forward/backward asymmetry of and . We find that these anisotropic flows are larger on the Au-going side than the Cu-going side, while the asymmetry tends to go away in very peripheral collisions. We also make predictions on transverse momentum spectra of identified hadrons and longitudinal decorrelations of charged particles, where the average decorrelation of elliptic flow in asymmetric Cu+Au collisions is found to be stronger than that in Au+Au collisions.

    Comments:
    9 pages, 10 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2004.06385 [pdf]
    EPJA(2020)·10 citations
  4. 07

    [Submitted on 14 Apr 2020] (cross-list from nucl-ex)

    Study of excitations in medium-mass nuclei with peripheral heavy ion charge-exchange reactions

    J. L. Rodriguez-Sanchez · J. Benlliure · I. Vidaña · H. Lenske · C. Scheidenberger · J. Vargas · H. Alvarez-Pol · Y. Ayyad · J. Atkinson · T. Aumann · S. Beceiro-Novo · K. Boretzky and 17 other authors

    Isobaric single charge-exchange reactions, changing nuclear charges by one unit but leaving the mass partitions unaffected, have been for the first time investigated by peripheral collisions of Sn ions accelerated up to 1\textit{A} GeV at the GSI facilities. The high-resolving power of the FRS spectrometer allows us to obtain -type isobaric charge-exchange cross sections with an uncertainty of and to separate quasi-elastic and inelastic components in the missing-energy spectra of the ejectiles. The inelastic component is associated to the excitation of the (1232) isobar resonance and the emission of pions in s-wave both in the target and projectile nucleus, while the quasi-elastic contribution is associated to the nuclear spin-isospin response of nucleon-hole excitations. An apparent shift of the -resonance peak of 63 MeV is observed when comparing the missing-energy spectra obtained from the measurements with proton and carbon targets. A detailed analysis, performed with a theoretical model for the reactions, indicates that this observation can be simply interpreted as a change in the relative magnitude between the contribution of the excitation of the resonance in the target and in the projectile.

    Subjects:
    Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2004.06404 [pdf]
    PLB(2020)·18 citations
  5. 08

    [Submitted on 14 Apr 2020] (cross-list from hep-ph)

    Anomalous magnetohydrodynamics with constant anisotropic electric conductivities

    Ren-jie Wang🇨🇳 · Patrick Copinger🇯🇵 · Shi Pu🇨🇳

    We study anomalous magnetohydrodynamics in a longitudinal boost invariant Bjorken flow with constant anisotropic electric conductivities as outlined in Ref. [1]. For simplicity, we consider a neutral fluid and a force-free magnetic field in the transverse direction. We derived analytic solutions of the electromagnetic fields in the laboratory frame, the chiral density, and the energy density as functions of proper time.

    Comments:
    5 pages, proceedings for Quark Matter 2019
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2004.06408 [pdf]
    NPA(2021)·16 citations
  6. 09

    [Submitted on 13 Apr 2020] (cross-list from hep-ph)

    Mass spectrum of pseudo-scalar glueballs from a Bethe-Salpeter approach with the rainbow-ladder truncation

    L.P. Kaptari🇷🇺 · B. Kämpfer🇩🇪

    We suggest a framework based on the rainbow approximation to the Dyson-Schwinger and Bethe-Salpeter equations with effective parameters adjusted to lattice QCD data to calculate the masses of the ground and excited states of pseudo-scalar glueballs. The structure of the truncated Bethe-Salpeter equation with the gluon and ghost propagators as solutions of the truncated Dyson-Schwinger equations is analysed in Landau gauge. Both, the Bete-Salpeter and Dyson-Schwinger equations, are solved numerically within the same rainbow-ladder truncation with the same effective parameters which ensure consistency of the approach. We found that with a set of parameters, which provides a good description of the lattice data within the Dyson-Schwinger approach, the solutions of the Bethe Salpeter equation for the pseudo-scalar glueballs exhibit a rich mass spectrum which also includes the ground and excited states predicted by lattice calculations. The obtained mass spectrum contains also several intermediate excitations beyond the lattice approaches. The partial Bethe-Salpeter amplitudes of the pseudo-scalar glueballs are presented as well.

    Comments:
    20 pages, 6 figures. arXiv admin note: text overlap with arXiv:1811.01479
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2004.06523 [pdf]
    Few Body Syst.(2020)·22 citations

Affiliations

first authorsco-authorsvia INSPIRE