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Nuclear Theory·nucl-th

Tuesday·February 24, 2015

8 papers—5 primary·3 cross-listed

All8Primary5Cross-lists3
  1. 01

    [Submitted on 21 Feb 2015]

    Alpha-cluster structure in even-even nuclei around Mo

    M. A. Souza · H. Miyake

    : The -cluster model was successful for describing spectroscopic properties of light nuclei near the shell closures. Evidences of the -cluster structure in Mo were shown, motivating the search for the same structure in other intermediate mass nuclei. : The systematic analysis of the -cluster structure in Mo and four even-even neighbouring nuclei. : The -cluster model with the local potential approach. : A good general description of the experimental ground state bands is obtained with only one variable parameter. It is shown that the employed potential is weakly dependent on the angular momentum and such dependence may be described satisfactorily by a simple -dependent factor for the five nuclei. The radial parameter of the potential reveals a linear trend in relation to the total nuclear radius and the sum of the -cluster and core radii. The calculated transition rates reproduce correctly the order of magnitude of almost all experimental data without the use of effective charges. The rms intercluster separations and reduced -widths obtained for the ground state bands point to a reduction of the -cluster intensity with the increasing spin. Negative parity bands are calculated and compared to available experimental levels. The volume integral per nucleon pair and rms radii were calculated for the studied potentials, revealing a similarity with the real parts of the optical potentials used to describe the Zr and Mo elastic scattering at several energies. : This work strongly indicates the presence of similar structures for the even-even nuclei of the Mo region.

    Comments:
    15 pages, 9 figures; accepted for publication in Physical Review C
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1502.06042 [pdf]
    PRC(2015)·31 citations
  2. 02

    [Submitted on 22 Feb 2015]

    Hadrons from Coalescence plus Fragmentation in AA collisions from RHIC to LHC energy

    Vincenzo Minissale🇮🇹 · Francesco Scardina🇮🇹 · Vincenzo Greco🇮🇹

    In a coalescence plus independent fragmentation approach we calculate the spectra of the main hadrons: in a wide range of transverse momentum from low up to about 10 GeV. The approach in its main features was developed several years ago at RHIC energy. Augmenting the model with the inclusion of some more main resonance decays, we show that the approach correctly predicts the evolution of the spectra from RHIC to LHC energy and in particular the baryon-to-meson ratios that reach a value of the order of unit at . This is achieved without any change of the coalescence parameters. The more recent availability of experimental data up to for spectrum as well as for and shows some lack of yield in a limited range around 6 GeV. This indicates that the baryons spectra from AKK fragmentation functions are too flat at . We also show that in a coalescence plus fragmentation approach one predicts a nearly independent ratio up to followed by a significant decrease at higher . Such a behavior is driven by a similar radial flow effect at and the dominance of fragmentation for at larger .

    Comments:
    11 pages, 12 figures Added the figure and discussion about the proton/phi ratio, as in the accepted version for pubblication
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1502.06213 [pdf]
    PRC(2015)·80 citations
  3. 03

    [Submitted on 22 Feb 2015]

    Cluster virial expansion for quark and nuclear matter

    David Blaschke🇵🇱

    We employ the derivable approach to many particle systems with strong correlations that can lead to the formation of bound states (clusters) of different size. We define a generic form of functionals that is fully equivalent to a selfconsistent cluster virial expansion up to the second virial coefficient for interactions among the clusters. As examples we consider nuclei in nuclear matter and hadrons in quark matter, with particular attention to the case of the deuterons in nuclear matter and mesons in quark matter. We derive a generalized Beth-Uhlenbeck equation of state, where the quasiparticle virial expansion is extended to include arbitrary clusters. The approach is applicable to nonrelativistic potential models of nuclear matter as well as to relativistic field theoretic models of quark matter. It is particularly suited for a description of cluster formation and dissociation in hot, dense matter.

    Comments:
    8 pages, 5 figures, Proceedings of the XXII International Baldin Seminar on High Energy Physics Problems, 15-20 September 2014, JINR Dubna, Russia
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1502.06279 [pdf]
    PoS(2015)·6 citations
  4. 04

    [Submitted on 23 Feb 2015]

    Cluster states and isoscalar monopole transitions of Mg

    Y. Chiba · M. Kimura

    We investigate structure of the excited states of Mg populated by isoscalar monopole transition from the ground state on the basis of antisymmetrized molecular dynamics calculation with Gogny D1S interaction. The calculated isoscalar monopole strength function shows reasonable agreement with experiment and is consistent with other theoretical calculation. The structure of the excited states with pronounced isoscalar monopole transitions are analyzed. It is found that the , and states have mixed nature of mean-field and cluster, and that the state is dominated by C+C cluster configuration. In addition, it is predicted that -pentagon+ states appear around 23 MeV.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1502.06325 [pdf]
    PRC(2015)·54 citations
  5. 05

    [Submitted on 23 Feb 2015]

    Microscopic analysis of Be elastic scattering on protons and nuclei and breakup processes of Be within the Be+ cluster model

    V.K. Lukyanov · D.N. Kadrev · E.V. Zemlyanaya · K. Spasova · K.V. Lukyanov · A.N. Antonov · M.K. Gaidarov

    The density distributions of Be and Be nuclei obtained within the quantum Monte Carlo (QMC) model and the generator coordinate method (GCM) are used to calculate the microscopic optical potentials (OPs) and cross sections of elastic scattering of these nuclei on protons and C at energies MeV/nucleon. The real part of the OP is calculated using the folding model with the exchange terms included, while the imaginary part of the OP that reproduces the phase of scattering is obtained in the high-energy approximation (HEA). In this hybrid model of OP the free parameters are the depths of the real and imaginary parts obtained by fitting the experimental data. The well known energy dependence of the volume integrals is used as a physical constraint to resolve the ambiguities of the parameter values. The role of the spin-orbit potential and the surface contribution to the OP is studied for an adequate description of available experimental elastic scattering cross section data. Also, the cluster model, in which Be consists of a -halo and the Be core, is adopted. Within the latter, the breakup cross sections of Be nucleus on Be, Nb, Ta, and U targets and momentum distributions of Be fragments are calculated and compared with the existing experimental data.

    Comments:
    14 pages, 10 figures, 3 tables, accepted for publication in Physical Review C
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1502.06425 [pdf]
    PRC(2015)·17 citations

Affiliations

first authorsco-authorsvia INSPIRE