PaperPanorama

Nuclear Theory·nucl-th

Wednesday·June 27, 2018

6 papers2 primary·4 cross-listed

  1. 01

    [Submitted on 26 Jun 2018]

    Reduced sensitivity of the cross sections to the deuteron model beyond adiabatic approximation

    M. Gómez-Ramos🇪🇸 · N. K. Timofeyuk🇬🇧

    It has recently been reported [Phys. Rev. Lett. 117, 162502 (2016)] that (d, p) cross sections can be very sensitive to the n-p interactions used in the adiabatic treatment of deuteron breakup with nonlocal nucleon-target optical potentials. To understand to what extent this sensitivity could originate in the inaccuracy of the adiabatic approximation we have developed a leading-order local- equivalent continuum-discretized coupled-channel model that accounts for non-adiabatic effects in the presence of nonlocality of nucleon optical potentials. We have applied our model to the astro- physically relevant reaction AlAl using two different n-p potentials associated with the lowest and the highest n-p kinetic energy in the short-range region of their interaction, respectively. Our calculations reveal a significant reduction of the sensitivity to the high n-p momenta thus confirming that it is mostly associated with theoretical uncertainties of the adiabatic approximation itself. The non-adiabatic effects in the presence of nonlocality were found to be stronger than those in the case of the local optical potentials. These results argue for extending the analysis of the reactions, measured for spectroscopic studies, beyond the adiabatic approximation.

    Comments:
    6 pages, 3 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1806.09877 [pdf]
    PRC(2018)·15 citations
  2. 02

    [Submitted on 25 Jun 2018]

    Constraints on the equation of state from the stability condition of neutron stars

    P.S. Koliogiannis🇬🇷 · Ch.C. Moustakidis🇬🇷

    The stellar equilibrium and collapse, including mainly white dwarfs, neutron stars and supper massive stars, is an interplay between general relativistic effects and the equation of state of nuclear matter. In the present work, we use the Chandrasekhar criterion of stellar instability by employing a large number of realistic equations of state (EoS) of neutron star matter. We mainly focus on the critical point of transition from stable to unstable configuration. This point corresponds to the maximum neutron star mass configuration. We calculate, in each case, the resulting compactness parameter, , and the corresponding effective adiabatic index, . The role of the trial function is presented and discussed in details. We found that it holds a model-independent relation between and . This statement is strongly supported by the large number of EoS and it is also corroborated by using analytical solutions of the Einstein's field equations. In addition, we present and discuss the relation between the maximum rotation rate and the adiabatic index close to the instability limit. Accurate observational measurements of the upper bound of the neutron star mass and the corresponding radius, in connection with the present predictions, may help to impose constraints on the high density part of the neutron star equation of state.

    Comments:
    15 pages, 1 table, 12 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
    arXiv:
    1806.09999 [pdf]
    Astrophys.Space Sci.(2019)·31 citations

Affiliations

first authorsco-authorsvia INSPIRE