PaperPanorama
FAQ

Nuclear Theory·nucl-th

Tuesday·January 8, 2019

12 papers—6 primary·6 cross-listed

All12Primary6Cross-lists6
  1. 07

    [Submitted on 5 Jan 2019] (cross-list from astro-ph.HE)

    Origin of the Heaviest Elements: the Rapid Neutron-Capture Process

    John J. Cowan🇺🇸 · Christopher Sneden🇺🇸 · James E. Lawler🇺🇸 · Ani Aprahamian🇺🇸 · Michael Wiescher🇺🇸 · Karlheinz Langanke🇩🇪 · Gabriel Martínez-Pinedo🇩🇪 · Friedrich-Karl Thielemann🇨🇭

    The production of about half of the heavy elements found in nature is assigned to a specific astrophysical nucleosynthesis process: the rapid neutron capture process (r-process). Although this idea has been postulated more than six decades ago, the full understanding faces two types of uncertainties/open questions: (a) The nucleosynthesis path in the nuclear chart runs close to the neutron-drip line, where presently only limited experimental information is available, and one has to rely strongly on theoretical predictions for nuclear properties. (b) While for many years the occurrence of the r-process has been associated with supernovae, more recent studies have cast substantial doubts on this environment. Alternative scenarios include the mergers of neutron stars, neutron-star black hole mergers, but possibly also rare classes of supernovae as well as hypernovae/collapsars with polar jet ejecta and also accretion disk outflows related to the collapse of fast rotating massive stars with high magnetic fields. Stellar r-process abundance observations, have provided insights into, and constraints on the frequency of and conditions in the responsible stellar production sites. One of them, neutron star mergers, was just identified and related to the Gravitational Wave event GW170817. High resolution observations, increasingly more precise due to improved experimental atomic data, have been particularly important in defining the heavy element abundance patterns of the old halo stars, and thus determining the extent, and nature, of the earliest nucleosynthesis in our Galaxy. Combining new results and important breakthroughs in the related nuclear, atomic and astronomical fields of science, this review attempts to provide an answer to the question "How Were the Elements from Iron to Uranium Made?" (Abridged)

    Comments:
    96 pages, 42 figures, 2 tables, author copy manuscript published in Reviews of Modern Physics
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1901.01410 [pdf]
    RMP(2021)·574 citations
  2. 08

    [Submitted on 5 Jan 2019] (cross-list from hep-ph)

    Radiative corrections to the jet quenching parameter in dilute and dense media

    Jean-Paul Blaizot🇫🇷 · Fabio Dominguez🇪🇸

    We extend the calculation of radiative corrections to momentum broadening in a QCD medium to include processes where single scattering dominates over multiple soft scatterings. Our analysis focusses on processes that are enhanced by a potentially large double logarithmic contribution. We demonstrate that such double logarithmic contributions emerge in calculations of momentum broadening in dilute systems where only single scattering occurs. We show how the different regimes, multiple versus single scattering, constrain different parts of the phase space.

    Comments:
    15 pages
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1901.01448 [pdf]
    PRD(2019)·17 citations
  3. 09

    [Submitted on 6 Jan 2019] (cross-list from hep-ph)

    Chiral Kinetic Theory from Effective Field Theory Revisited

    Shu Lin🇨🇳 · Aradhya Shukla🇨🇳

    We revisit the chiral kinetic equation from high density effective theory approach, finding a chiral kinetic equation differs from counterpart derived from field theory in high order terms in the expansion, but in agreement with the equation derived in on-shell effective field theory upon identification of cutoff. By using reparametrization transformation properties of the effective theory, we show that the difference in kinetic equations from two approaches are in fact expected. It is simply due to different choices of degree of freedom by effective theory and field theory. We also show that they give equivalent description of the dynamics of chiral fermions.

    Comments:
    26 pages, extend discussion on reparametrization transformation and its relation with side-jump
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Nuclear Theory (nucl-th)
    arXiv:
    1901.01528 [pdf]
    JHEP(2019)·45 citations
  4. 10

    [Submitted on 6 Jan 2019] (cross-list from hep-ph)

    The dispersion relation of the fast neutrino oscillation wave

    Changhao Yi🇺🇸 · Lei Ma🇺🇸 · Joshua D. Martin🇺🇸 · Huaiyu Duan (UNM)

    A dense neutrino medium can support flavor oscillation waves which are coherent among different momentum modes of the neutrinos. The dispersion relation (DR) branches of such a wave with complex frequencies and/or wave numbers can lead to the exponential growth of the wave amplitude which in turn will engender a collective flavor transformation in the neutrino medium. In this work we propose that the complex DR branches of the neutrino oscillation wave should be bound by the critical points of the DR. We demonstrate how this theory can be applied to the neutrino medium with an (approximate) axial symmetry about the propagation direction of the neutrino oscillation wave. We also show how the flavor instabilities in this medium can be identified by tracing the critical points of the DR as the electron lepton number distribution of the neutrino medium is changed continuously.

    Comments:
    11 pages, 4 figures. Small textual changes for clarification
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
    arXiv:
    1901.01546 [pdf]
    PRD(2019)·86 citations
  5. 11

    [Submitted on 7 Jan 2019] (cross-list from cond-mat.quant-gas)

    Time fractals and discrete scale invariance with trapped ions

    Dean Lee · Jacob Watkins · Dillon Frame · Gabriel Given · Rongzheng He · Ning Li · Bing-Nan Lu · Avik Sarkar

    We show that a one-dimensional chain of trapped ions can be engineered to produce a quantum mechanical system with discrete scale invariance and fractal-like time dependence. By discrete scale invariance we mean a system that replicates itself under a rescaling of distance for some scale factor, and a time fractal is a signal that is invariant under the rescaling of time. These features are reminiscent of the Efimov effect, which has been predicted and observed in bound states of three-body systems. We demonstrate that discrete scale invariance in the trapped ion system can be controlled with two independently tunable parameters. We also discuss the extension to n-body states where the discrete scaling symmetry has an exotic heterogeneous structure. The results we present can be realized using currently available technologies developed for trapped ion quantum systems.

    Comments:
    4 + 5 pages (main + supplemental materials), 2 + 3 figures (main + supplemental materials), version to appear in Physical Review A Rapid Communications
    Subjects:
    Quantum Gases (cond-mat.quant-gas); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
    arXiv:
    1901.01661 [pdf]
    PRA(2019)·6 citations
  6. 12

    [Submitted on 7 Jan 2019] (cross-list from nucl-ex)

    Observation of excited states in Mg sheds light on nuclear forces and shell evolution

    J. S. Randhawa · R. Kanungo · M. Holl · J. D. Holt · P. Navratil · S. R. Stroberg · G. Hagen · G. R. Jansen · M. Alcorta · C. Andreoiu · C. Barnes · C. Burbadge and 26 other authors

    The exotic Borromean nucleus Mg with = 8, located at the proton drip-line provides a unique testing ground for nuclear forces and the evolution of shell structure in the neutron-deficient region. We report on the first observation of proton unbound resonances together with bound states in Mg from the Mg(,) reaction performed at TRIUMF. Phenomenological shell-model calculations offer a reasonable description. However, our experimental results present a challenge for current first-principles nuclear structure approaches and point to the need for improved chiral forces and {\it ab initio} calculations. Furthermore, the differential cross section of the first excited state is compared with distorted-wave Born approximation calculations to deduce a neutron quadrupole deformation parameter of =0.460.21. This provides the first indication of a possible weakening of the = 8 shell closure at the proton drip-line.

    Comments:
    6 pages, 4 figures
    Subjects:
    Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1901.01741 [pdf]
    PRC(2019)·17 citations

Affiliations

first authorsco-authorsvia INSPIRE