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Nuclear Theory·nucl-th

Wednesday·November 7, 2018

6 papers—2 primary·4 cross-listed

All6Primary2Cross-lists4
  1. 01

    [Submitted on 6 Nov 2018]

    Microscopic treatment of energy partition in fission

    M. Albertsson · B.G. Carlsson · T. Døssing · P. Möller · J. Randrup · S. Åberg

    The transformation of an atomic nucleus into two excited fission fragments is modeled as a strongly damped evolution of the nuclear shape, until scission occurs at a small critical neck radius, at which point the mass, charge, and shape of each fragment are extracted. The available excitation energy then is divided statistically on the basis of the microscopic level densities. This approach takes account of the important (and energy-dependent) finite-size effects. After the fragments have been fully accelerated and their shapes have relaxed to their equilibrium form, they undergo sequential neutron evaporation. The dependence of the resulting mean neutron multiplicity on the fragment mass, (A), including the dependence on the initial excitation energy of the fissioning compound nucleus, is in good agreement with the observed behavior, as demonstrated here for U(n,f).

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1811.02283 [pdf]
    6 citations
  2. 02

    [Submitted on 6 Nov 2018]

    Low-lying collective excited states in non-integrable pairing models based on stationary-phase approximation to path integral

    Fang Ni · Nobuo Hinohara · Takashi Nakatsukasa

    For a description of large-amplitude collective motion associated with nuclear pairing, requantization of time-dependent mean-field dynamics is performed using the stationary-phase approximation (SPA) to the path integral. We overcome the difficulty of the SPA, which is known to be applicable to integrable systems only, by developing a requantization approach combining the SPA with the adiabatic self-consistent collective coordinate method (ASCC+SPA). We apply the ASCC+SPA to multi-level pairing models, which are non-integrable systems, to study the nuclear pairing dynamics. The ASCC+SPA gives a reasonable description of low-lying excited states in non-integrable pairing systems.

    Comments:
    13 pages, 12 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1811.02352 [pdf]
    PRC(2018)·3 citations
  3. 03

    [Submitted on 5 Nov 2018] (cross-list from hep-ph)

    Primordial Lithium Puzzle and the Axion Quark Nugget Dark Matter Model

    Victor V. Flambaum🇦🇺 · Ariel R. Zhitnitsky🇨🇦

    Astrophysics today faces a number of mysteries which defiant their resolutions in spite of drastic improvements in instrumental design, better technique being developed, and gradual improvements in theoretical and computation methods over last decades. Primordial Lithium Puzzle is known to stay with us for at least two decades, and it is very likely that its final resolution will require some fundamentally new ideas, novel frameworks and a non-conventional paradigms. We propose that Primordial Lithium Puzzle finds its natural resolution within the so-called Axion Quark Nugget (AQN) dark matter model. This model was invented long ago as a natural explanation of the observed ratio without any references to BBN physics. In this new paradigm, in contrast with conventional WIMP (Weakly Interacting Massive Particle) framework the dark matter (DM) takes the form of the macroscopically large quark nuggets without requiring any new fields beyond the standard model physics, except for the axion. The time evolution of these AQNs in primordial soup at KeV suggests a strong suppression of the abundances of nuclei with high charges . This suppression mechanism represents the resolution of the primordial lithium abundance within AQN dark matter scenario.

    Comments:
    New appendix added for clarification. Final version to appear in Phys. Rev. D
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Nuclear Theory (nucl-th)
    arXiv:
    1811.01965 [pdf]
    PRD(2019)·39 citations
  4. 04

    [Submitted on 5 Nov 2018] (cross-list from hep-ph)

    Non-extensive Motivated Parton Fragmentation Functions

    Adam Takacs🇭🇺 · Gergely Gábor Barnaföldi🇭🇺

    A new form of fragmentation function is presented here, motivated by earlier non-extensive studies of jet fragmentation. We parametrized our Tsallis-like function on pion spectra and compared it to the most common fragmentation function parametrizations. It is shown that the new form is in agreement with earlier parametrizations, furthermore, its scale evolution overlap better with the experimental data.

    Comments:
    4 pages, 2 figures, Presented at Hot Quarks 2018. Submitted to MDPI Proceedings
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1811.01974 [pdf]
    MDPI Proc.(2019)·3 citations
  5. 05

    [Submitted on 6 Nov 2018] (cross-list from nucl-ex)

    Dominance of tensor correlations in high-momentum nucleon pairs studied by (p,pd) reaction

    S. Terashima · L. Yu · H.J. Ong · I. Tanihata · S. Adachi · N. Aoi · P.Y. Chan · H. Fujioka · M. Fukuda · H. Geissel · G. Gey · J. Golak and 20 other authors

    The isospin character of p-n pairs at large relative momentum has been observed for the first time in the 16O ground state. A strong population of the J,T=1,0 state and a very weak population of the J,T=0,1 state were observed in neutron pick up domain of 16O(p,pd) at 392 MeV. This strong isospin dependence at large momentum transfer is not reproduced by the distorted-wave impulse approximation calculations with known spectroscopic amplitudes. The results indicate the presence of high-momentum protons and neutrons induced by the tensor interactions in ground state of 16O.

    Comments:
    12 pages, 4 figures, accepted for publication in Physical Review Letters
    Subjects:
    Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1811.02118 [pdf]
    PRL(2018)·32 citations
  6. 06

    [Submitted on 6 Nov 2018] (cross-list from hep-lat)

    QCD phase diagram for finite imaginary chemical potential with HISQ fermions

    Jishnu Goswami🇩🇪 · Frithjof Karsch🇩🇪 · Anirban Lahiri🇩🇪 · Christian Schmidt🇩🇪

    We present results from an ongoing study of the phase diagram of (2+1)-flavor QCD using the HISQ action with smaller than physical light quark masses in the Roberge-Weiss (RW) plane on lattices with temporal extent . We find that the endpoint of the order RW transition line remains order at least down to light quark masses corresponding to Goldstone pion masses of MeV. Furthermore, we show that the chiral condensate is sensitive to the RW transition and may serve as a energy-like operator characterizing universal behavior close to the RW endpoint.

    Comments:
    7pages, 11 figures, Prepared for the proceedings of LATTICE2018, held at Michigan State University, East Lansing, Michigan, USA
    Subjects:
    High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1811.02494 [pdf]
    PoS(2018)·11 citations

Affiliations

first authorsco-authorsvia INSPIRE