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Nuclear Theory·nucl-th

Friday·December 4, 2015

10 papers—4 primary·6 cross-listed

All10Primary4Cross-lists6
  1. 01

    [Submitted on 2 Dec 2015]

    An analytic hydrodynamical model of rotating 3D expansion in heavy-ion collisions

    M. I. Nagy🇭🇺 · T. Csörgő🇭🇺

    A new exact and analytic solution of non-relativistic fireball hydrodynamics is presented. It describes an expanding triaxial ellipsoid that rotates around one of its principal axes. The observables are calculated using simple analytic formulas. Azimuthal oscillation of the off-diagonal Bertsch-Pratt radii of Bose-Einstein correlations as well as rapidity dependent directed and third flow measurements provide means to determine the magnitude of the rotation of the fireball. Observing this rotation and its dependence on collision energy may lead to new information on the equation of state of the strongly interacting quark gluon plasma produced in high energy heavy ion collisions.

    Comments:
    8 pages, 8 figures. Invited talk of M. I. Nagy at WPCF 2014, Gyöngyös, Hungary, 25-29 August 2014 and invited contribution to the Gribov-85 Memorial Volume "Exploring Quantum Field Theory", (World Scientific, Singapore in press)
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1512.00888 [pdf]
    Int.J.Mod.Phys.A(2016)·5 citations
  2. 02

    [Submitted on 2 Dec 2015]

    Charm production in Pb+Pb collisions at the Large Hadron Collider energy

    Taesoo Song🇩🇪 · Hamza Berrehrah🇩🇪 · Daniel Cabrera🇩🇪 · Wolfgang Cassing🇩🇪 · Elena Bratkovskaya🇩🇪

    We study charm production in Pb+Pb collisions at 2.76 TeV in the Parton-Hadron-String-Dynamics transport approach and the charm dynamics in the partonic and hadronic medium. The charm quarks are produced through initial binary nucleon-nucleon collisions by using the PYTHIA event generator taking into account the (anti-)shadowing incorporated in the EPS09 package. The produced charm quarks interact with off-shell massive partons in the quark-gluon plasma and are hadronized into mesons through coalescence or fragmentation close to the critical energy density, and then interact with hadrons in the final hadronic stage with scattering cross sections calculated in an effective Lagrangian approach with heavy-quark spin symmetry. The PHSD results show a reasonable and elliptic flow of mesons in comparison to the experimental data for Pb+Pb collisions at = 2.76 TeV from the ALICE Collaboration. We also study the effect of temperature-dependent off-shell charm quarks in relativistic heavy-ion collisions. We find that the scattering cross sections are only moderately affected by off-shell charm degrees of freedom. However, the position of the peak of for mesons depends on the strength of the scalar partonic forces which also have an impact on the meson elliptic flow. The comparison with experimental data on the suggests that the repulsive force is weaker for off-shell charm quarks as compared to that for light quarks. Furthermore, the effects from radiative charm energy loss appear to be low compared to the collisional energy loss up to transverse momenta of 15 GeV/c.

    Comments:
    13 pages, 11 figures, to be published in PRC
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1512.00891 [pdf]
    PRC(2016)·189 citations
  3. 03

    [Submitted on 3 Dec 2015]

    Systematic study of complete fusion suppression in reactions involving weakly bound nuclei at energies above the Coulomb barrier

    Bing Wang🇨🇳 · Wei-Juan Zhao🇨🇳 · Alexis Diaz-Torres🇮🇹 · En-Guang Zhao🇨🇳 · Shan-Gui Zhou🇨🇳

    Complete fusion excitation functions of reactions involving breakup are studied by using the empirical coupled-channel (ECC) model with breakup effects considered. An exponential function with two parameters is adopted to describe the prompt-breakup probability in the ECC model. These two parameters are fixed by fitting the measured prompt-breakup probability or the complete fusion cross sections. The suppression of complete fusion at energies above the Coulomb barrier is studied by comparing the data with the predictions from the ECC model without the breakup channel considered. The results show that the suppression of complete fusion are roughly independent of the target for the reactions involving the same projectile.

    Comments:
    9 pages, 6 figures, 3 tables
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1512.00960 [pdf]
    PRC(2016)·30 citations
  4. 04

    [Submitted on 3 Dec 2015]

    Ab-initio calculations of charge symmetry breaking in the A=4 hypernuclei

    Daniel Gazda🇸🇪 · Avraham Gal🇮🇱

    We report on ab-initio NCSM calculations of the A=4 mirror Lambda hypernuclei Lambda-4H and Lambda-4He, using the Bonn-Juelich LO chiral EFT YN potentials plus a CSB Lambda0--Sigma0 mixing vertex. In addition to reproducing rather well the 0+ (g.s.) and 1+ (exc.) binding energies, these four-body calculations demonstrate for the first time that the observed CSB splitting of mirror levels, reaching hundreds of keV for 0+ (g.s.), can be reproduced using realistic theoretical interaction models, although with a non-negligible momentum cutoff dependence. Our results are discussed in relation to recent measurements of the Lambda-4H (0+ g.s.) binding energy [MAMI A1 Collaboration, Phys. Rev. Lett. 114, 232501 (2015)] and the Lambda-4He (1+ exc.) excitation energy [J-PARC E13 Collaboration, Phys. Rev. Lett. 115, 222501 (2015)].

    Comments:
    v4 matches PRL publication, also updating Ref. [30], with more details and further discussion relegated to arXiv:1604.03434
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1512.01049 [pdf]
    PRL(2016)·72 citations

Affiliations

first authorsco-authorsvia INSPIRE