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Nuclear Theory·nucl-th

Tuesday·January 30, 2018

11 papers—7 primary·4 cross-listed

All11Primary7Cross-lists4
  1. 01

    [Submitted on 26 Jan 2018]

    Precision mass measurements on neutron-rich rare-earth isotopes at JYFLTRAP - reduced neutron pairing and implications for the -process calculations

    M. Vilen · J.M. Kelly · A. Kankainen · M. Brodeur · A. Aprahamian · L. Canete · T. Eronen · A. Jokinen · T. Kuta · I.D. Moore · M.R. Mumpower · D.A. Nesterenko and 7 other authors

    The rare-earth peak in the -process abundance pattern depends sensitively on both the astrophysical conditions and subtle changes in nuclear structure in the region. This work takes an important step elucidating the nuclear structure and reducing the uncertainties in -process calculations via precise atomic mass measurements at the JYFLTRAP double Penning trap. Nd, Pm, Sm, and Gd have been measured for the first time and the precisions for Nd, Pm, Eu, Gd, and Tb have been improved considerably. Nuclear structure has been probed via two-neutron separation energies and neutron pairing energy metrics . The data do not support the existence of a subshell closure at . Neutron pairing has been found to be weaker than predicted by theoretical mass models. The impact on the calculated -process abundances has been studied. Substantial changes resulting in a smoother abundance distribution and a better agreement with the solar -process abundances are observed.

    Comments:
    8 pages, 4 figures, accepted for publication in Physical Review Letters
    Subjects:
    Nuclear Experiment (nucl-ex); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th)
    arXiv:
    1801.08940 [pdf]
    PRL(2018)·57 citations
  2. 02

    [Submitted on 26 Jan 2018]

    Effective-range function methods for charged particle collisions

    David Gaspard · Jean-Marc Sparenberg

    Different versions of the effective-range function method for charged particle collisions are studied and compared. In addition, a novel derivation of the standard effective-range function is presented from the analysis of Coulomb wave functions in the complex plane of the energy. The recently proposed effective-range function denoted as [Phys. Rev. C 96, 034601 (2017)] and an earlier variant [Hamilton et al., Nucl. Phys. B 60, 443 (1973)] are related to the standard function. The potential interest of for the study of low-energy cross sections and weakly bound states is discussed in the framework of the proton-proton collision. The resonant state of the proton-proton collision is successfully computed from the extrapolation of instead of the standard function. It is shown that interpolating can lead to useful extrapolation to negative energies, provided scattering data are known below one nuclear Rydberg energy (12.5 keV for the proton-proton system). This property is due to the connection between and the effective-range function by Hamilton et al. that is discussed in detail. Nevertheless, such extrapolations to negative energies should be used with caution because is not analytic at zero energy. The expected analytic properties of the main functions are verified in the complex energy plane by graphical color-based representations.

    Comments:
    17 pages, 11 figures, 46 references; typos fixed
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1801.08980 [pdf]
    PRC(2018)·15 citations
  3. 03

    [Submitted on 26 Jan 2018]

    Tilted-axis wobbling in odd-mass nuclei

    R. Budaca

    A triaxial rotor Hamiltonian with a rigidly aligned high- quasiparticle is treated by a time-dependent variational principle, using angular momentum coherent states. The resulting classical energy function have three unique critical points in a space of generalized conjugate coordinates, which can minimize the energy for specific ordering of the inertial parameters and a fixed angular momentum state. Due to the symmetry of the problem, there are only two unique solutions, corresponding to wobbling motion around a principal axis and respectively a tilted-axis. The wobbling frequencies are obtained after a quantization procedure and then used to calculate and transition probabilities. The analytical results are employed in the study of the wobbling excitations of Pr nucleus, which is found to undergo a transition from low angular momentum transverse wobbling around a principal axis toward a tilted-axis wobbling at higher angular momentum.

    Comments:
    12 pages, 7 figures, 3 tables
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1801.08982 [pdf]
    PRC(2018)·34 citations
  4. 04

    [Submitted on 27 Jan 2018]

    J/psi with large pT probing the early stage of relativistic heavy ion collisions

    Li Guansong (Tianjin U) · Li Yuhuan (Tianjin U) · Shi Wei (Tianjin U)

    We study the charmonium suppression in different evolutions of quark gluon plasma (QGP) based on the transport model. In the colliding energies of Large Hadron Collider, charmonium final yields are dominated by the recombination of charm and anti-charm quarks in the deconfined phase. Heavy quark diffusions depend less on the shear viscosity of the bulk medium, which makes the J/psi nuclear modification factor in the entire pT bin shows weak dependence on the shear viscosity of QGP. However, charmonium with high transverse momentum pT, can only be produced in the early stage of nuclear collisions, and is sensitive to the initial energy density (or temperature) of QGP, and can be a probe of the initial dynamical evolutions of quark gluon plasma.

    Comments:
    It is too simple and need further improvements
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1801.09032 [pdf]
    0 citations
  5. 05

    [Submitted on 27 Jan 2018]

    Gamow-Teller transitions from high-spin isomers in nuclei

    H. Z. Liang · H. Sagawa · M. Sasano · T. Suzuki · M. Honma

    Gamow-Teller (GT) transitions from high-spin isomers are studied using the sum-rule approach and the shell model. The GT transition strengths from the high-spin isomeric states show a stronger collectivity than those from the ground states in two nuclei, Fe and Ag. It is argued that the spin-up and spin-down Fermi spheres involved in the GT transitions from the high-spin isomeric states play important roles. These Fermi spheres are analogous to the isospin-up and isospin-down Fermi spheres for the GT transitions from the ground states in nuclei and create a strong collectivity.

    Comments:
    6 pages, 2 figures, and 3 tables
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1801.09076 [pdf]
    PRC(2018)·7 citations
  6. 06

    [Submitted on 29 Jan 2018]

    Light nuclei production as a probe of the QCD phase diagram

    Kai-Jia Sun🇨🇳 · Lie-Wen Chen🇨🇳 · Che Ming Ko🇺🇸 · Jie Pu🇨🇳 · Zhangbu Xu🇺🇸

    It is generally believed that the quark-hadron transition at small values of baryon chemical potentials is a crossover but changes to a first-order phase transition with an associated critical endpoint (CEP) as increases. Such a -dependent quark-hadron transition is expected to result in a double-peak structure in the collision energy dependence of the baryon density fluctuation in heavy-ion collisions with one at lower energy due to the spinodal instability during the first-order phase transition and another at higher energy due to the critical fluctuations in the vicinity of the CEP. By analyzing the data on the , d and H yields in central heavy-ion collisions within the coalescence model for light nuclei production, we find that the relative neutron density fluctuation at kinetic freeze-out indeed displays a clear peak at GeV and a possible strong re-enhancement at GeV. Our findings thus provide a strong support for the existence of a first-order phase transition at large and its critical endpoint at a smaller in the temperature versus baryon chemical potential plane of the QCD phase diagram.

    Comments:
    7 pages, 2 figures, 1 table. Significantly expanded to include some details and discussions. Accepted version to appear in PLB
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1801.09382 [pdf]
    PLB(2018)·129 citations
  7. 07

    [Submitted on 29 Jan 2018]

    Origin of a maximum of astrophysical factor in heavy-ion fusion reactions at deep subbarrier energies

    K. Hagino · A.B. Balantekin · N.W. Lwin · Ei Shwe Zin Thein

    The hindrance phenomenon of heavy-ion fusion cross sections at deep subbarrier energies often accompanies a maximum of an astrophysical factor at a threshold energy for fusion hindrance. We argue that this phenomenon can naturally be explained when the fusion excitation function is fitted with two potentials, with a larger (smaller) logarithmic slope at energies lower (higher) than the threshold energy. This analysis clearly suggests that the astrophysical factor provides a convenient tool to analyze the deep subbarrier hindrance phenomenon, even though the factor may have a strong energy dependence for heavy-ion systems unlike that for astrophysical reactions.

    Comments:
    4 pages, 4 figures
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1801.09393 [pdf]
    PRC(2018)·6 citations

Affiliations

first authorsco-authorsvia INSPIRE