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Nuclear Theory·nucl-th

Monday·March 30, 2015

4 papers—3 primary·1 cross-listed

All4Primary3Cross-lists1
  1. 01

    [Submitted on 27 Mar 2015]

    Angular momentum projected multi-cranked configuration mixing for reliable calculation of high-spin rotational bands

    Mitsuhiro Shimada · Shingo Tagami · Yoshifumi R. Shimizu

    By employing the angular momentum projection technique we propose a method to reliably calculate the quantum spectrum of nuclear collective rotation. The method utilizes several cranked mean-field states with different rotational frequencies and they are superposed in the sense of the configuration mixing or the generator coordinate method, after performing the projection; the idea was originally suggested by Peierls-Thouless in 1962. It is found that the spectrum as a result of the configuration mixing does not essentially depend on chosen sets of cranking frequencies if the number of mean-field states utilized in the mixing is larger than a certain small value. We apply this method to three examples employing the Gogny D1S effective interaction and show that it is useful to study high-spin rotational bands by means of the angular momentum projection method.

    Comments:
    32 pages, 25 figures. Revised; mistake was found and corrected in calculation of 164Er; new figures and sentences are added by a request of journal (B(E2), mixing probability)
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1503.07963 [pdf]
    PTEP(2015)·12 citations
  2. 02

    [Submitted on 27 Mar 2015]

    Neutrino-nucleus reactions and their role for supernova dynamics and nucleosynthesis

    K. G. Balasi🇬🇷 · K. Langanke🇩🇪 · G. Martínez-Pinedo🇩🇪

    The description of nuclear reactions induced by supernova neutrinos has witnessed significant progress during the recent years. At the energies and momentum transfers relevant for supernova neutrinos neutrino-nucleus cross sections are dominated by allowed transitions, however, often with non-negligible contributions from (first) forbidden transitions. For several nuclei allowed Gamow-Teller strength distributions could be derived from charge-exchange reactions and from inelastic electron scattering data. Importantly the diagonalization shell model has been proven to accurately describe these data and hence became the appropriate tool to calculate the allowed contributions to neutrino-nucleus cross sections for supernova neutrinos. Higher multipole contributions are usually calculated within the framework of the Quasiparticle Random Phase Approximation, which describes the total strength and the position of the giant resonances quite well. This manuscript reviews the recent progress achieved in calculating supernova-relevant neutrino-nucleus cross sections and discusses its verification by data. Moreover, the review summarizes also the impact which neutrino-nucleus reactions have on the dynamics of supernovae and on the associated nucleosynthesis. These include the absorption of neutrinos by nuclei (the inverse of nuclear electron capture which is the dominating weak-interaction process during collapse), inelastic neutrino-nucleus scattering and nuclear de-excitation by neutrino-pair emission. We also discuss the role of neutrino-induced reactions for the recently discovered process, for the r-process and for the neutrino process, for which neutrino-nucleus reactions have the largest impact. Finally, we briefly review neutrino-nucleus reactions important for the observation of supernova neutrinos by earthbound detectors. (Abridged)

    Comments:
    77 pages, 29 figures, 4 tables, submitted to Progress in Particle and Nuclear Physics
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
    arXiv:
    1503.08095 [pdf]
    PPNP(2015)·86 citations
  3. 03

    [Submitted on 27 Mar 2015]

    Langevin dynamics and decoherence of heavy quarks at high temperatures

    Yukinao Akamatsu🇯🇵

    A Langevin equation of heavy quarks in high-temperature quark-gluon plasma is derived. The dynamics of heavy quark color is coupled with the phase space dynamics and causes a macroscopic superposition state of heavy quark momentum. Decoherence of the superposition state allows one to use a classical description. The time scale of decoherence gives an appropriate discretization time scale for the classical Langevin equation, where is heavy quark mass and is heavy quark momentum diffusion constant.

    Comments:
    v3: 8 pages, 1 figure, published version
    Subjects:
    Nuclear Theory (nucl-th); Statistical Mechanics (cond-mat.stat-mech); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1503.08110 [pdf]
    PRC(2015)·25 citations
  4. 04

    [Submitted on 27 Mar 2015] (cross-list from cond-mat.quant-gas)

    Multiple period states of the superfluid Fermi gas in an optical lattice

    Sukjin Yoon · Franco Dalfovo · Takashi Nakatsukasa · Gentaro Watanabe

    We study multiple period states of a two-component unpolarized superfluid Fermi gas in an optical lattice along the Bardeen-Cooper-Schrieffer (BCS) to Bose-Einstein condensate (BEC) crossover. The existence of states whose period is a multiple of the lattice spacing is a direct consequence of the non-linear behavior of the gas, which is due to the presence of the order parameter associated with superfluidity. By solving Bogoliubov-de Gennes equations for a superfluid flow with finite quasimomentum, we find that, in the BCS side of the crossover, the multiple period states can be energetically favorable compared to the normal Bloch states and their survival time against dynamical instability drastically increases, suggesting that these states can be accessible in current experiments, in sharp contrast to the situation in BECs.

    Comments:
    16 pages, 9 figures; to appear in New J. Phys
    Subjects:
    Quantum Gases (cond-mat.quant-gas); Solar and Stellar Astrophysics (astro-ph.SR); Superconductivity (cond-mat.supr-con); Nuclear Theory (nucl-th)
    arXiv:
    1503.07976 [pdf]
    New J.Phys.(2016)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE