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Nuclear Theory·nucl-th

Friday·October 27, 2017

11 papers—7 primary·4 cross-listed

All11Primary7Cross-lists4
  1. 08

    [Submitted on 23 Oct 2017] (cross-list from nucl-ex)

    Dawning of the N=32 shell closure seen through precision mass measurements of neutron-rich titanium isotopes

    E. Leistenschneider🇨🇦 · M.P. Reiter🇨🇦 · S. Ayet San Andrés🇩🇪 · B. Kootte🇨🇦 · J.D. Holt🇨🇦 · P. Navrátil🇨🇦 · C. Babcock🇨🇦 · C. Barbieri🇬🇧 · B.R. Barquest🇨🇦 · J. Bergmann🇩🇪 · J. Bollig🇨🇦 · T. Brunner🇨🇦 and 33 other authors

    A precision mass investigation of the neutron-rich titanium isotopes Ti was performed at TRIUMF's Ion Trap for Atomic and Nuclear science (TITAN). The range of the measurements covers the shell closure and the overall uncertainties of the Ti mass values were significantly reduced. Our results confirm the existence of a weak shell effect at , establishing the abrupt onset of this shell closure. Our data were compared with state-of-the-art \textit{ab-initio} shell model calculations which, despite very successfully describing where the shell gap is strong, overpredict its strength and extent in titanium and heavier isotones. These measurements also represent the first scientific results of TITAN using the newly commissioned Multiple-Reflection Time-of-Flight Mass Spectrometer (MR-TOF-MS), substantiated by independent measurements from TITAN's Penning trap mass spectrometer.

    Subjects:
    Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1710.08537 [pdf]
    PRL(2018)·117 citations
  2. 09

    [Submitted on 25 Oct 2017] (cross-list from hep-ph)

    Phenomenology of neutron-antineutron conversion

    Susan Gardner🇺🇸 · Xinshuai Yan🇺🇸

    We consider the possibility of neutron-antineutron () conversion, in which the change of a neutron into an antineutron is mediated by an external source, as can occur in a scattering process. We develop the connections between conversion and oscillation, in which a neutron spontaneously tranforms into an antineutron, noting that if oscillation occurs in a theory with B-L violation, then conversion can occur also. We show how an experimental limit on conversion could connect concretely to a limit on oscillation, and vice versa, using effective field theory techniques and baryon matrix elements computed in the M.I.T. bag model.

    Comments:
    19 pages, REVTeX, 3 figures; typos fixed and minor clarifications and refs. added
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1710.09292 [pdf]
    PRD(2018)·15 citations
  3. 10

    [Submitted on 25 Oct 2017] (cross-list from hep-ph)

    Melting and freeze-out conditions of hadrons in a thermal medium

    Juan M. Torres-Rincon🇩🇪 · Joerg Aichelin🇩🇪 · Hannah Petersen🇩🇪 · Jean-Bernard Rose🇩🇪 · Joseph Tindall🇬🇧

    We describe two independent frameworks which provide unambiguous determinations of the deconfinement and the decoupling conditions of a relativistic gas at finite temperature. First, we use the Polyakov-Nambu-Jona-Lasinio model to compute meson and baryon masses at finite temperature and determine their melting temperature as a function of their strangeness content. Second, we analyze a simple expanding gas within a Friedmann-Robertson-Walker metric, which admits a well-defined decoupling mechanism. We examine the decoupling time as a function of the particle mass and cross section. We find evidences of an inherent dependence of the hadronization and freeze-out conditions on flavor, and on mass and cross section, respectively.

    Comments:
    4 pages, 3 figures. Contribution to the proceedings of the 17th International Conference on Strangeness in Quark Matter (SQM2017), Utrecht, the Netherlands, 10-15 July 2017
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1710.09406 [pdf]
    EPJ Web Conf.(2018)·0 citations
  4. 11

    [Submitted on 26 Oct 2017] (cross-list from hep-ph)

    Collectivity without plasma in hadronic collisions

    Christian Bierlich🇸🇪 · Gösta Gustafson🇸🇪 · Leif Lönnblad🇸🇪

    We present a microscopic model for collective effects in high multiplicity proton--proton collisions, where multiple partonic subcollisions give rise to a dense system of strings. From lattice calculations we know that QCD strings are transversely extended, and we argue that this should result in a transverse pressure and expansion, similar to the flow in a deconfined plasma. The model is implemented in the PYTHIA8 Monte Carlo event generator, and we find that it can qualitatively reproduce the long range azimuthal correlations forming a near-side ridge in high multiplicity proton--proton events at LHC energies.

    Comments:
    12 pages, 4 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1710.09725 [pdf]
    PLB(2018)·132 citations

Affiliations

first authorsco-authorsvia INSPIRE