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Nuclear Theory·nucl-th

Friday·January 30, 2015

6 papers—2 primary·4 cross-listed

All6Primary2Cross-lists4
  1. 01

    [Submitted on 29 Jan 2015]

    Neutron star equations of state with optical potential constraint

    Sofija Antić🇩🇪 · Stefan Typel🇩🇪

    Nuclear matter and neutron stars are studied in the framework of an extended relativistic mean-field (RMF) model with higher-order derivative and density dependent couplings of nucleons to the meson fields. The derivative couplings lead to an energy dependence of the scalar and vector self-energies of the nucleons. It can be adjusted to be consistent with experimental results for the optical potential in nuclear matter. Several parametrisations, which give identical predictions for the saturation properties of nuclear matter, are presented for different forms of the derivative coupling functions. The stellar structure of spherical, non-rotating stars is calculated for these new equations of state (EoS). A substantial softening of the EoS and a reduction of the maximum mass of neutron stars is found if the optical potential constraint is satisfied.

    Comments:
    19 pages, 4 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1501.07393 [pdf]
    NPA(2015)·11 citations
  2. 02

    [Submitted on 29 Jan 2015]

    Heavy quark diffusion in pre-equilibrium stage of heavy ion collisions

    Santosh K. Das🇮🇹 · Marco Ruggieri🇮🇹 · Surasree Mazumder🇮🇳 · Vincenzo Greco🇮🇹 · Jan-e Alam🇮🇳

    The drag and diffusion coefficients of heavy quarks (HQs) have been evaluated in the pre-equilibrium phase of the evolving fireball produced in heavy ion collisions at RHIC and LHC energies. The KLN and classical Yang-Mills spectra have been used for describing the momentum distributions of the gluons produced just after the collisions but before they thermalize. The interaction of the HQs with these gluons has been treated within the framework of perturbative QCD. We have observed that the HQs are dragged almost equally by the kinetically equilibrated and out-of-equilibrium gluonic systems. We have also noticed that the HQs diffusion in the pre-equilibrium gluonic phase is as fast as in the kinetically equilibrated gluons. Moreover, the diffusion is faster in the pre-equilibrium phase than in the chemically equilibrated quark-gluon plasma. These findings may have significant impact on the analysis of experimental results on the elliptic flow and the high momentum suppression of the open charm and beauty hadrons.

    Comments:
    11 pages,11 figures, Accepted for publication in Journal of Physics G
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1501.07521 [pdf]
    J.Phys.G(2015)·34 citations
  3. 03

    [Submitted on 16 Jan 2015] (cross-list from hep-ph)

    Quarkonium Binding and Entropic Force

    Helmut Satz🇩🇪

    A Q-Qbar bound state represents a balance between repulsive kinetic and attractive potential energy. In a hot quark-gluon plasma, the interaction potential experiences medium effects. Color screening modifies the attractive binding force between the quarks, while the increase of entropy with Q-Qbar separation gives rise to a growing repulsion. We study the role of these phenomena for in-medium Q-Qbar binding and dissociation. It is found that the relevant potential for Q-Qbar binding is the free energy F; with increasing Q-Qbar separation, further binding through the internal energy U is compensated by repulsive entropic effects.

    Comments:
    11 pages, 8 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    1501.03940 [pdf]
    EPJC(2015)·16 citations
  4. 04

    [Submitted on 28 Jan 2015] (cross-list from hep-ph)

    Polarization effects in double open-charm production at LHCb

    Miguel G. Echevarria🇳🇱 · Tomas Kasemets🇳🇱 · Piet J. Mulders🇳🇱 · Cristian Pisano🇳🇱

    Double open-charm production is one of the most promising channels to disentangle single from double parton scattering (DPS) and study different properties of DPS. Several studies of the DPS contributions have been made. A missing ingredient so far has been the study of polarization effects, arising from spin correlations between the two partons inside an unpolarized proton. We investigate the impact polarization has on the double open-charm cross section. We show that the longitudinally polarized gluons can give significant contributions to the cross section, but for most of the considered kinematic region only have a moderate effect on the shape. We compare our findings to the LHCb data in the D0D0 final state, identify observables where polarization does have an impact on the distribution of the final state particles, and suggest measurements which could lead to first experimental indications of, or limits on, polarization in DPS.

    Comments:
    16 pages, 13 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1501.07291 [pdf]
    JHEP(2015)·32 citations
  5. 05

    [Submitted on 29 Jan 2015] (cross-list from physics.atom-ph)

    Nuclear structure effects in light muonic atoms

    Krzysztof Pachucki · Albert Wienczek

    Nuclear structure corrections to energy levels of light muonic atoms are derived with particular attention to the nuclear mass dependence. The obtained result for the 2P-2S transition of 1.717(19) meV serves for determination of the nuclear charge radius from the spectroscopic measurement in muonic deuterium.

    Comments:
    6 pages, 1 table, published version
    Subjects:
    Atomic Physics (physics.atom-ph); Nuclear Theory (nucl-th)
    arXiv:
    1501.07451 [pdf]
    PRA(2015)·48 citations
  6. 06

    [Submitted on 29 Jan 2015] (cross-list from physics.acc-ph)

    Modelling proton-induced reactions at low energies in the MARS15 code

    Igor L. Rakhno · Nikolai V. Mokhov (Fermilab) Konstantin K. Gudima (IAP, Chisinau)

    An implementation of both the ALICE code and TENDL evaluated nuclear data library in order to describe nuclear reactions by low-energy projectiles in the Monte Carlo code MARS15 is presented. Comparisons between results of modelling and experimental data on reaction cross sections and secondary particle distributions are shown as well.

    Comments:
    11 pp. Presented at the 12th Meeting on Shielding Aspects of Accelerators, Targets and Irradiation Facilities (SATIF-12), April 28-30, 2014, Fermi National Accelerator Laboratory, Batavia, Illinois, USA
    Subjects:
    Accelerator Physics (physics.acc-ph); Nuclear Theory (nucl-th)
    arXiv:
    1501.07597 [pdf]
    1 citation

Affiliations

first authorsco-authorsvia INSPIRE