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Nuclear Theory·nucl-th

Monday·September 7, 2015

6 papers—3 primary·3 cross-listed

All6Primary3Cross-lists3
  1. 04

    [Submitted on 4 Sept 2015] (cross-list from hep-ph)

    Heavy quark potential from QCD-related effective coupling

    Cesar Ayala🇪🇸 · Pedro Gonzalez🇪🇸 · Vicente Vento🇪🇸

    We implement our past investigations in the quark-antiquark interaction through a non-perturbative running coupling defined in terms of a gluon mass function, similar to that used in some Schwinger-Dyson approaches. This coupling leads to a quark-antiquark potential, which satisfies not only asymptotic freedom but also describes linear confinement correctly. From this potential, we calculate the bottomonium and charmonium spectra below the first open flavor meson-meson thresholds and show that for a small range of values of the free parameter determining the gluon mass function an excellent agreement with data is attained.

    Comments:
    13 pages, 4 figures; v3: version accepted for publication in Journal of Physics G
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1509.01382 [pdf]
    J.Phys.G(2016)·8 citations
  2. 05

    [Submitted on 4 Sept 2015] (cross-list from hep-ph)

    Preserving Local Gauge Invariance with t-Channel Regge Exchange

    Helmut Haberzettl🇺🇸 · Xiao-Yun Wang🇨🇳 · Jun He🇨🇳

    Considering single-meson photo- and electroproduction off a baryon, it is shown how to restore local gauge invariance that was broken by replacing standard Feynman-type meson exchange in the t-channel by exchange of a Regge trajectory. This is achieved by constructing a contact current whose four-divergence cancels the gauge-invariance-violating contributions resulting from all states above the base state on the Regge trajectory. To illustrate the procedure, modifications necessary for the process are discussed in some detail. We also provide the general expression for the contact current for an arbitrary reaction.

    Comments:
    11 pages, 2 figures, RevTeX4-1
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1509.01536 [pdf]
    PRC(2015)·24 citations
  3. 06

    [Submitted on 4 Sept 2015] (cross-list from astro-ph.HE)

    Neutrino flavor instabilities in a time-dependent supernova model

    Sajad Abbar🇺🇸 · Huaiyu Duan (UNM)🇺🇸

    A dense neutrino medium such as that inside a core-collapse supernova can experience collective flavor conversion or oscillations because of the neutral-current weak interaction among the neutrinos. This phenomenon has been studied in a restricted, stationary supernova model which possesses the (spatial) spherical symmetry about the center of the supernova and the (directional) axial symmetry around the radial direction. Recently it has been shown that these spatial and directional symmetries can be broken spontaneously by collective neutrino oscillations. In this paper we analyze the neutrino flavor instabilities in a time-dependent supernova model. Our results show that collective neutrino oscillations start at approximately the same radius in both the stationary and time-dependent supernova models unless there exist very rapid variations in local physical conditions on timescales of a few microseconds or shorter. Our results also suggest that collective neutrino oscillations can vary rapidly with time in the regimes where they do occur which need to be studied in time-dependent supernova models.

    Comments:
    5 pages, 2 figures, version to appear in PLB
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1509.01538 [pdf]
    PLB(2015)·72 citations

Affiliations

first authorsco-authorsvia INSPIRE