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Nuclear Theory·nucl-th

Friday·May 4, 2018

13 papers—7 primary·6 cross-listed

All13Primary7Cross-lists6
  1. 01

    [Submitted on 2 May 2018]

    Pairing in Nuclei: Exact Solutions

    A.B. Balantekin

    Pairing plays an essential role in describing nuclear spectra and attempts to describe it has a long history in nuclear physics. Many theoretical tools were developed to treat the pairing problem either exactly or at various levels of approximation. In this contribution to the proceedings of a conference honoring the career of Taka Otsuka, recent developments in the exact solutions of the pairing problem are described.

    Comments:
    6 pages, Proceedings of Ito International Research Center (IIRC) symposium "Perspectives of the physics of nuclear structure", November 2017
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1805.00970 [pdf]
    JPS Conf.Proc.(2018)·0 citations
  2. 02

    [Submitted on 2 May 2018]

    Universal correlations in the nuclear symmetry energy, slope parameter, and curvature

    Jeremy W. Holt · Yeunhwan Lim

    From general Fermi liquid theory arguments, we derive correlations among the symmetry energy (J), its slope parameter (L), and curvature (K_sym) at nuclear matter saturation density. We argue that certain properties of these correlations do not depend on details of the nuclear forces used in the calculation. We derive as well a global parametrization of the density dependence of the symmetry energy that we show is more reliable, especially at low densities, than the usual Taylor series expansion around saturation density. We then benchmark these predictions against explicit results from chiral effective field theory.

    Comments:
    6 pages, 4 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1805.01000 [pdf]
    PLB(2018)·41 citations
  3. 03

    [Submitted on 3 May 2018]

    Angular dependence of eta photoproduction in photon-induced reaction

    Jun-Zhen Wang🇨🇳 · Bao-Chun Li🇨🇳

    Photoproduction of eta mesons from nucleons can provide valuable information about the excitation spectrum of the nucleons. The angular dependence of photoproduction in the photon-induced reaction is investigated in the multi-source thermal model. The results are compared with experimental data from the decay mode. They are in good agreement with the experimental data. It is shown that the movement factor increases linearly with the photon beam energies. And, the deformation and translation of emission sources are visually given in the formalism.

    Comments:
    15 pages, 9 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1805.01155 [pdf]
    Adv.High Energy Phys.(2018)·0 citations
  4. 04

    [Submitted on 3 May 2018]

    Localization of pairing correlations in nuclei within relativistic mean field models

    R.-D. Lasseri🇫🇷 · J.-P. Ebran🇫🇷 · E. Khan🇫🇷 · N. Sandulescu🇷🇴

    We analyze the localization properties of two-body correlations induced by pairing in the framework of relativistic mean field (RMF) models. The spatial properties of two-body correlations are studied for the pairing tensor in coordinate space and for the Cooper pair wave function. The calculations are performed both with Relativistic-Hatree-Bogoliubov (RHB) and RMF+Projected-BCS (PBCS) models and taking as examples the nuclei Ni, Sn and Pb. It is shown that the coherence length have the same pattern as in previous non-relativistic HFB calculations, i.e., it is maximum in the interior of the nucleus and drops to a minimum in the surface region. In the framework of RMF+PBCS we have also analysed, for the particular case of Sn, the dependence of the coherence length on the intensity of the pairing force. This analysis indicates that pairing is reducing the coherence length by about 25-30 compared to the RMF limit.

    Comments:
    8 pages, 7 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1805.01188 [pdf]
    PRC(2018)·3 citations
  5. 05

    [Submitted on 3 May 2018]

    Extension of the ratio method to proton-rich nuclei

    X. Y. Yun · F. Colomer · D. Y. Pang · P. Capel

    The ratio method has been developed to improve the study of one-neutron halo nuclei through reactions. By taking the ratio of angular distributions for two processes, viz. breakup and elastic scattering, this new observable is nearly independent of the reaction mechanism and hence much more sensitive to the projectile structure than the cross sections for each single process. We study the extension of the ratio method to proton-rich nuclei and also explore the optimum experimental conditions for measuring this new observable. We compare accurate dynamical calculations of reactions for proton-rich projectiles to the prediction of the ratio method. We use the dynamical eikonal approximation that provides good results for this kind of reactions at intermediate energy. Our tests for 8B, an archteypical one-proton halo nucleus, on Pb, Ni, and C targets at 44 MeV/nucleon show that, the ratio works less well than for neutron halos due to the non-negligible Coulomb interaction between the valence proton and the target. Nevertheless, the ratio method still provides pertinent information about nuclear structure on the proton-rich side of the valley of stability. Interestingly the method is not affected if energy ranges-or bins-are considered in the projectile continuum. This makes the ratio easier to measure experimentally by increasing the breakup cross section. We also extend our analysis to 17F, 25Al, and 27P, whose study is of interest to both nuclear astrophysics and nuclear structure. We show that, albeit less precise than for one-neutron halo nuclei, nuclear-structure information can be inferred from the ratio method applied to exotic proton-rich nuclei. In particular, when the valence proton is loosely bound in an or orbital, viz. for proton halo nuclei, detailed structure information can be obtained through this new reaction observable.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1805.01204 [pdf]
    J.Phys.G(2019)·3 citations
  6. 06

    [Submitted on 3 May 2018]

    Monte Carlo approach to the excluded-volume hadron resonance gas in grand canonical and canonical ensembles

    Volodymyr Vovchenko🇩🇪 · Mark I. Gorenstein🇩🇪 · Horst Stoecker🇩🇪

    The Monte Carlo (MC) procedure for sampling the hadron yields within hadron resonance gas (HRG) model is presented. The effects of excluded-volume due to the finite hadron eigenvolumes and of exact charge conservation within the canonical ensemble (CE) formulation are simultaneously taken into account with the help of the importance sampling technique combined with the rejection sampling. The MC procedure allows one to calculate arbitrary moments of the event-by-event hadron yields. Note that the CE formulation for the excluded-volume HRG has not been considered before. The MC simulations coincide with the known analytic results in the thermodynamic limit for the excluded-volume HRG in the grand canonical ensemble and for the CE of non-interacting particles. The MC procedure is applied to study the simultaneous excluded-volume and CE effects. These effects are considered within the full HRG to calculate the particle number fluctuations and to estimate the finite size effects.

    Comments:
    29 pages, 5 figures. To be published in Physical Review C
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1805.01402 [pdf]
    PRC(2018)·18 citations
  7. 07

    [Submitted on 3 May 2018]

    New exact solutions of relativistic hydrodynamics for longitudinally expanding fireballs

    T. Csorgo🇭🇺 · G. Kasza🇭🇺 · M. Csanad🇭🇺 · Z. Jiang🇨🇳

    We present new, exact, finite solutions of relativistic hydrodynamics for longitudinally expanding fireballs for arbitrary constant value of the speed of sound. These new solutions generalize earlier, longitudinally finite, exact solutions, from an unrealistic to a reasonable equation of state, characterized by a temperature independent (average) value of the speed of sound. Observables like the rapidity density and the pseudorapidity density are evaluated analytically, resulting in simple and easy to fit formulae that can be matched to the high energy proton-proton and heavy ion collision data at RHIC and LHC. In the longitudinally boost-invariant limit, these new solutions approach the Hwa-Bjorken solution and the corresponding rapidity distributions approach a rapidity plateaux.

    Comments:
    22 pages, 7 figures, resubmitted to the MDPI Journal Universe, with minor clarifications added, and the axis labels of Fig. 7 improved
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1805.01427 [pdf]
    Universe(2018)·22 citations

Affiliations

first authorsco-authorsvia INSPIRE