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Nuclear Theory·nucl-th

Thursday·February 26, 2015

5 papers—3 primary·2 cross-listed

All5Primary3Cross-lists2
  1. 01

    [Submitted on 25 Feb 2015]

    Calculating broad neutron resonances in a cut-off Woods-Saxon potential

    Á. Baran · Cs. Noszály · P. Salamon · T. Vertse

    In a cut-off Woods-Saxon (CWS) potential with realistic depth -matrix poles being far from the imaginary wave number axis form a sequence where the distances of the consecutive resonances are inversely proportional with the cut-off radius value, which is an unphysical parameter. Other poles lying closer to the imaginary wave number axis might have trajectories with irregular shapes as the depth of the potential increases. Poles being close repel each other, and their repulsion is responsible for the changes of the directions of the corresponding trajectories. The repulsion might cause that certain resonances become antibound and later resonances again when they collide on the imaginary axis. The interaction is extremely sensitive to the cut-off radius value, which is an apparent handicap of the CWS potential.

    Comments:
    5 pages, 3 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1502.07111 [pdf]
    EPJA(2015)·4 citations
  2. 02

    [Submitted on 25 Feb 2015]

    Low-Energy Antinucleon-Nucleus Interaction Revisited

    E. Friedman🇮🇱

    Annihilation cross sections of antiprotons and antineutrons on the proton between 50 and 400 MeV/c show Coulomb focusing below 200 MeV/c and almost no charge-dependence above 200 MeV/c. Similar comparisons for heavier targets are not possible for lack of overlap between nuclear targets studied with and beams. Interpolating between -nucleus annihilation cross sections with the help of an optical potential to compare with -nucleus annihilation cross sections reveal unexpected features of Coulomb interactions in the latter. Direct comparisons between -nucleus and -nucleus annihilations at very low energies could be possible if cross sections are measured on the same targets and at the same energies as the available cross sections for . Such measurements may be feasible in the foreseeable future.

    Comments:
    8 pages, 4 figures, to appear in Proceedings of the International Conference on Exotic Atoms and Related Topics (EXA 2014), Vienna, Austria, 15-19 September 2014
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1502.07127 [pdf]
    Hyperfine Interact.(2015)·4 citations
  3. 03

    [Submitted on 25 Feb 2015]

    Electron capture cross sections for stellar nucleosynthesis

    P.G. Giannaka🇬🇷 · T.S. Kosmas🇬🇷

    In the first stage of this work, we perform detailed calculations for the cross sections of the electron capture on nuclei under laboratory conditions. Towards this aim we exploit the advantages of a refined version of the proton-neutron quasi-particle random-phase approximation (pn-QRPA) and carry out state-by-state evaluations of the rates of exclusive processes that lead to any of the accessible transitions within the chosen model space. In the second stage of our present study, we translate the above mentioned -capture cross sections to the stellar environment ones by inserting the temperature dependence through a Maxwell-Boltzmann distribution describing the stellar electron gas. As a concrete nuclear target we use the isotope, which belongs to the iron group nuclei and plays prominent role in stellar nucleosynthesis at core collapse supernovae environment.

    Comments:
    23 pages, 4 figures, 7 tables, Article Ref.:Advances in High Energy Physics, Article ID 398796, in press
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1502.07225 [pdf]
    Adv.High Energy Phys.(2015)·16 citations
  4. 04

    [Submitted on 25 Feb 2015] (cross-list from cond-mat.quant-gas)

    Photoassociation of Universal Efimov Trimers

    Betzalel Bazak · Nir Barnea

    In view of recent experiments in ultracold atomic systems, the photoassociation of Efimov trimers, composed of three identical bosons, is studied utilizing the multipole expansion. We study both the normal hierarchy case, where one-body current is dominant, and the strong hierarchy case, relevant for photoassociation in ultracold atoms, where two-body current is dominant. For identical particles in the normal hierarchy case, the leading contribution comes from the r^2 s-mode operator and from the quadrupole d-mode operator. The s-mode reaction is found to be dominant at low temperature, while as the temperature increases the d-mode becomes as significant. For the strong hierarchy case, the leading contribution comes from a 2-body s-wave {\delta} operator. In both cases log periodic oscillations are found in the cross section. For large but finite scattering length the amplitude of the oscillations becomes larger in comparison to infinite scattering length case. We apply our theory to photoassociation of 7Li ultracold atoms and show a good fit to the available experimental results.

    Subjects:
    Quantum Gases (cond-mat.quant-gas); Nuclear Theory (nucl-th)
    arXiv:
    1502.07119 [pdf]
    J.Phys.B(2015)·0 citations
  5. 05

    [Submitted on 25 Feb 2015] (cross-list from hep-ph)

    Dimension-5 CP-odd operators: QCD mixing and renormalization

    T. Bhattacharya🇺🇸 · V. Cirigliano🇺🇸 · R. Gupta🇺🇸 · E. Mereghetti🇺🇸 · B. Yoon🇺🇸

    We study the off-shell mixing and renormalization of flavor-diagonal dimension-5 T- and P-odd operators involving quarks, gluons, and photons, including quark electric dipole and chromo-electric dipole operators. We present the renormalization matrix to one-loop in the scheme. We also provide a definition of the quark chromo-electric dipole operator in a regularization-independent momentum-subtraction scheme suitable for non-perturbative lattice calculations and present the matching coefficients with the scheme to one-loop in perturbation theory, using both the naive dimensional regularization and 't Hooft-Veltman prescriptions for .

    Comments:
    52 pages, 5 figures, 6 tables. Added section with comparison to DeltaS=1 chromo-magnetic operator
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
    arXiv:
    1502.07325 [pdf]
    PRD(2015)·70 citations

Affiliations

first authorsco-authorsvia INSPIRE