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Nuclear Theory·nucl-th

Friday·April 15, 2016

7 papers—3 primary·4 cross-listed

All7Primary3Cross-lists4
  1. 04

    [Submitted on 13 Apr 2016] (cross-list from astro-ph.HE)

    Observational Constraints on Neutron Star Masses and Radii

    M. Coleman Miller (U. Maryland) · Frederick K. Lamb (U. Illinois)

    Precise and reliable measurements of the masses and radii of neutron stars with a variety of masses would provide valuable guidance for improving models of the properties of cold matter with densities above the saturation density of nuclear matter. Several different approaches for measuring the masses and radii of neutron stars have been tried or proposed, including analyzing the X-ray fluxes and spectra of the emission from neutron stars in quiescent low-mass X-ray binary systems and thermonuclear burst sources; fitting the energy-dependent X-ray waveforms of rotation-powered millisecond pulsars, burst oscillations with millisecond periods, and accretion-powered millisecond pulsars; and modeling the gravitational radiation waveforms of coalescing double neutron star and neutron star -- black hole binary systems. We describe the strengths and weaknesses of these approaches, most of which currently have substantial systematic errors, and discuss the prospects for decreasing the systematic errors in each method.

    Comments:
    20 pages, 1 figure
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
    arXiv:
    1604.03894 [pdf]
    EPJA(2016)·100 citations
  2. 05

    [Submitted on 14 Apr 2016] (cross-list from nucl-ex)

    Spectroscopy of 46Ar by the (t,p) two-neutron transfer reaction

    K. Nowak · K. Wimmer · S. Hellgartner · D. Mücher · V. Bildstein · J. Diriken · J. Elseviers · L. P. Gaffney · R. Gernhäuser · J. Iwanicki · J. G. Johansen · M. Huyse and 15 other authors

    States in the nucleus Ar have been studied by a two-neutron transfer reaction at REX-ISOLDE (CERN). A beam of radioactive at an energy of 2.16~AMeV and a tritium loaded titanium target were used to populate by the t(,p) two-neutron transfer reaction. Protons emitted from the target were identified in the T-REX silicon detector array. The excitation energies of states in have been reconstructed from the measured angles and energies of recoil protons. Angular distributions for three final states were measured and based on the shape of the differential cross section an excited state at 3695~keV has been identified as . The angular differential cross section for the population of different states are compared to calculations using a reaction model employing both sequential and direct transfer of two neutrons. Results are compared to shell model calculations using state-of-the-art effective interactions.

    Comments:
    10 pages, 12 figures, PRC accepted
    Subjects:
    Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1604.04014 [pdf]
    PRC(2016)·22 citations
  3. 06

    [Submitted on 14 Apr 2016] (cross-list from physics.atom-ph)

    Atomic Parameters for the Transition of Ne I relevant in nuclear physics

    Jiguang Li · Michel Godefroid · Jianguo Wang

    We calculated the magnetic dipole hyperfine interaction constants and the electric field gradients of and levels of Ne I by using the multiconfiguration Dirac-Hartree-Fock method. The electronic factors contributing to the isotope shifts were also estimated for the nm transition connecting these two states. Electron correlation and relativistic effects including the Breit interaction were investigated in details. Combining with recent measurements, we extracted the nuclear quadrupole moment values for Ne and Ne with a smaller uncertainty than the current available data. Isotope shifts in the transition based on the present calculated field- and mass-shift parameters are in good agreement with the experimental values. However, the field shifts in this transition are two or three orders of magnitude smaller than the mass shifts, making rather difficult to deduce changes in nuclear charge mean square radii. According to our theoretical predictions, we suggest to use instead transitions connecting levels arising from the configuration to the ground state, for which the normal mass shift and specific mass shift contributions counteract each other, producing relatively small mass shifts that are only one order of magnitude larger than relatively large field shifts, especially for the transition.

    Subjects:
    Atomic Physics (physics.atom-ph); Nuclear Theory (nucl-th)
    arXiv:
    1604.04075 [pdf]
    J.Phys.B(2016)·3 citations
  4. 07

    [Submitted on 14 Apr 2016] (cross-list from hep-ph)

    Probing Transverse Momentum Broadening in Heavy Ion Collisions

    A.H. Mueller🇺🇸 · Bin Wu🇺🇸 · Bo-Wen Xiao🇨🇳 · Feng Yuan🇺🇸

    We study the dijet azimuthal de-correlation in relativistic heavy ion collisions as an important probe of the transverse momentum broadening effects of a high energy jet traversing the quark-gluon plasma. We take into account both the soft gluon radiation in vacuum associated with the Sudakov logarithms and the jet P_T-broadening effects in the QCD medium. We find that the Sudakov effects are dominant at the LHC, while the medium effects can play an important role at RHIC energies. This explains why the LHC experiments have not yet observed sizable P_T-broadening effects in the measurement of dijet azimuthal correlations in heavy ion collisions. Future investigations at RHIC will provide a unique opportunity to study the P_T-broadening effects and help to pin down the underlying mechanism for jet energy loss in a hot and dense medium.

    Comments:
    9 pages, 4 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1604.04250 [pdf]
    PLB(2016)·75 citations

Affiliations

first authorsco-authorsvia INSPIRE