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Nuclear Theory·nucl-th

Tuesday·December 23, 2014

17 papers—4 primary·13 cross-listed

All17Primary4Cross-lists13
  1. 01

    [Submitted on 19 Dec 2014]

    Thermal model for Pb+Pb collisions at TeV with explicit treatment of hadronic ground states

    Viktor Begun🇵🇱

    Various explanations of the anomalous proton to pion ratio at the LHC are discussed. The special emphasis is set on the Cracow thermal model with single freeze-out. This model allows to get a good agreement for both the mean hadron multiplicities and the spectra. Moreover, the values of the fit parameters indicate the possibility of pion Bose condensation in the most central collisions at the LHC. Therefore, a modification of the thermal framework is proposed that explicitly allows for the condensation in the ground state. The generalised model makes a link between equilibrium and non-equilibrium thermal models. It also suggests that the pion condensation may be formed in the central collisions.

    Comments:
    The reasons for the increase of the pion number and the decrease of the proton number, which allow the successful explanation of the proton puzzle, are clarified more explicitly
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1412.6532 [pdf]
    EPJ Web Conf.(2015)·7 citations
  2. 02

    [Submitted on 20 Dec 2014]

    Formation of hypermatter and hypernuclei within transport models in relativistic ion collisions

    A.S. Botvina (1,2)🇩🇪 · J. Steinheimer (1)🇩🇪 · E. Bratkovskaya (1)🇩🇪 · M. Bleicher (1)🇩🇪 · J. Pochodzalla (3,4) ((1) Frankfurt Institute for Advanced Studies, Frankfurt am Main, Germany (2) Institute for Nuclear Research RAS, Moscow, Russia (3) Helmholtz-Institut Mainz, Mainz, Germany (4) Institut fuer Kernphysik and PRISMA Cluster of Excellence, J.Gutenberg-University Mainz, Germany)🇩🇪

    Within a combined approach we investigate the main features of the production of hyper-fragments in relativistic heavy-ion collisions. The formation of hyperons is modelled within the UrQMD and HSD transport codes. To describe the hyperon capture by nucleons and nuclear residues a coalescence of baryons (CB) model was developed. We demonstrate that the origin of hypernuclei of various masses can be explained by typical baryon interactions, and that it is similar to processes leading to the production of conventional nuclei. At high beam energies we predict a saturation of the yields of all hyper-fragments, therefore, this kind of reactions can be studied with high yields even at the accelerators of moderate relativistic energies.

    Comments:
    9 pages, 9 figures, submitted to Phys. Lett. B
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1412.6665 [pdf]
    PLB(2015)·80 citations
  3. 03

    [Submitted on 22 Dec 2014]

    Signals of Deconfinement Phase Transition and Possible Energy Range of Its Detection

    K.A. Bugaev🇺🇦

    Here we thoroughly discuss the present status of the deconfinement phase transition signals outlined in the NICA White Paper 10.01. It is argued that none of the signals outlined in the NICA White Paper is prepared for experimental verification. At the same time we discuss the new irregularities and new signals of the deconfinement transition found recently within the realistic version of the hadron resonance gas model. All new findings evidence that the mixed quark-gluon-hadron phase can be reached at the center of mass energy of collision 4.3-4.9 GeV.

    Comments:
    12 pages, 4 figures, minor changes of text
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1412.6849 [pdf]
    0 citations
  4. 04

    [Submitted on 22 Dec 2014]

    Derivation of an optical potential for statically deformed rare-earth nuclei from a global spherical potential

    G. P. A. Nobre🇺🇸 · A. Palumbo🇺🇸 · F. S. Dietrich🇺🇸 · M. Herman🇺🇸 · D. Brown🇺🇸 · S. Hoblit🇺🇸

    The coupled-channel theory is a natural way of treating nonelastic channels, in particular those arising from collective excitations characterized by nuclear deformations. A proper treatment of such excitations is often essential to the accurate description of experimental nuclear-reaction data and to the prediction of a wide variety of scattering observables. Stimulated by recent work substantiating the near validity of the adiabatic approximation in coupled-channel calculations for scattering on statically deformed nuclei, we explore the possibility of generalizing a global spherical optical model potential (OMP) to make it usable in coupled-channel calculations on this class of nuclei. To do this, we have deformed the Koning-Delaroche global spherical potential for neutrons, coupling a sufficient number of states of the ground state band to ensure convergence. We present an extensive study of the effects of collective couplings and nuclear deformations on integrated cross sections as well as on angular distributions for neutron-induced reactions on statically deformed nuclei in the rare-earth region. We choose isotopes of three rare-earth elements (Gd, Ho, W), which are known to be nearly perfect rotors, to exemplify the results of the proposed method. Predictions from our model for total, elastic and inelastic cross sections, as well as for elastic and inelastic angular distributions, are in reasonable agreement with measured experimental data. These results suggest that the deformed Koning-Delaroche potential provides a useful regional neutron optical potential for the statically deformed rare earth nuclei.

    Comments:
    13 pages, 13 figures, 1 table. Version to be submitted to Physical Review C
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1412.7099 [pdf]
    PRC(2015)·13 citations

Affiliations

first authorsco-authorsvia INSPIRE