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Nuclear Theory·nucl-th

Friday·February 19, 2016

4 papers—2 primary·2 cross-listed

All4Primary2Cross-lists2
  1. 01

    Cooperative internal conversion process by proton exchange

    Péter Kálmán · Tamás Keszthelyi

    A generalization of the recently discovered cooperative internal conversion process is investigated theoretically. In the cooperative internal conversion process by proton exchange investigated the coupling of bound-free electron and proton transitions due to the dipole term of their Coulomb interaction permits cooperation of two nuclei leading to proton exchange and an electron emission. General expression of the cross section of the process obtained in the one particle spherical nuclear shell model is presented. As a numerical example the cooperative internal conversion process by proton exchange in is dealt with. As a further generalization, cooperative internal conversion process by heavy charged particle exchange and as an example of it the cooperative internal conversion process by triton exchange is discussed. The process is also connected to the field of nuclear waste disposal.

    nucl-th0 citations
  2. 02

    MAID-2015: update with new data and new resonances

    V.L. Kashevarov · L. Tiator · M. Ostrick

    Recent data for and photoproduction on protons obtained by the A2 Collaboration at MAMI are presented. The total cross section for photoproduction demonstrates a cusp at the energy corresponding to the threshold. The new data and existing data from GRAAL, CBELSA/TAPS, and CLAS collaborations have been analyzed by an expansion in terms of associated Legendre polynomials. %A Legendre decomposition shows the sensitivity to small partial-wave contributions. The isobar model MAID updated with channel and new resonances have been used to fit the new data. The new solution MAID-2015 reasonably good describes the data in the photon beam energy region up to 3.7 GeV.

    nucl-thnucl-exBled Workshops Phys.(2015)·16 citations
  3. 03

    Physics of Core-Collapse Supernovae in Three Dimensions: a Sneak Preview

    H.-Thomas Janka (1)🇩🇪 · Tobias Melson (1,2)🇩🇪 · Alexander Summa (1) ((1) MPI Astrophysics, Garching, (2) Physik Dept., TUM, Garching)🇩🇪

    Nonspherical mass motions are a generic feature of core-collapse supernovae, and hydrodynamic instabilities play a crucial role for the explosion mechanism. First successful neutrino-driven explosions could be obtained with self-consistent, first-principle simulations in three spatial dimensions (3D). But 3D models tend to be less prone to explosion than corresponding axisymmetric (2D) ones. This has been explained by 3D turbulence leading to energy cascading from large to small spatial scales, inversely to the 2D case, thus disfavoring the growth of buoyant plumes on the largest scales. Unless the inertia to explode simply reflects a lack of sufficient resolution in relevant regions, it suggests that some important aspect may still be missing for robust and sufficiently energetic neutrino-powered explosions. Such deficits could be associated with progenitor properties like rotation, magnetic fields or pre-collapse perturbations, or with microphysics that could lead to an enhancement of neutrino heating behind the shock. 3D simulations have also revealed new phenomena that are not present in 2D, for example spiral modes of the standing accretion shock instability (SASI) and a stunning dipolar lepton-emission self-sustained asymmetry (LESA). Both impose time- and direction-dependent variations on the detectable neutrino signal. The understanding of these effects and of their consequences is still in its infancy.

    ↳ astro-ph.SRhep-phnucl-thAnn.Rev.Nucl.Part.Sci.(2016)·453 citations
  4. 04

    Confronting fluctuations of conserved charges in central nuclear collisions at the LHC with predictions from Lattice QCD

    P. Braun-Munzinger🇩🇪 · A. Kalweit🇨🇭 · K. Redlich🇩🇪 · J. Stachel🇩🇪

    We construct net baryon number and strangeness susceptibilities as well as correlations between electric charge, strangeness and baryon number from experimental data on the particle production yields at midrapidity of the ALICE Collaboration at CERN. The data were taken in central Pb-Pb collisions at ~=~2.76~TeV and cover one unit of rapidity. We show that the resulting fluctuations and correlations are consistent with Lattice QCD results at the chiral crossover pseudocritical temperature 155 MeV. This agreement lends strong support to the assumption that the fireball created in these collisions is of thermal origin and exhibits characteristic properties expected in QCD at the transition from the quark gluon plasma to the hadronic phase. Since Lattice QCD calculations are performed at a baryochemical potential of = 0, the comparisons with LHC data are the most direct due to the vanishing baryon transport to midrapidity at these high energies.

    ↳ hep-phhep-latnucl-thNPA(2016)·7 citations

Affiliations

first authorsco-authorsvia INSPIRE