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Nuclear Theory·nucl-th

Wednesday·February 22, 2017

7 papers—4 primary·3 cross-listed

All7Primary4Cross-lists3
  1. 01

    [Submitted on 21 Feb 2017]

    Renormalization of chiral nuclear forces with multiple subtractions in peripheral channels

    E. F. Batista🇧🇷 · S. Szpigel🇧🇷 · V. S. Timóteo🇧🇷

    We analyse the renormalization of the of two-nucleon interaction with multiple subtractions in peripheral waves considering two chiral forces at N3LO. Phase shifts at low energies are then computed with several subtraction points below \mu = 10 / fm. We show that for most peripheral waves the phase shifts have nearly no dependence on the renormalization scale. In two cases the phase shifts converge slowly as the renormalization scale approaches \mu = 1 / fm and in one case the phase shifts presented oscillations with respect to the subtraction point \mu.

    Comments:
    21 pages, 12 figures, to appear in the special issue "Few-Body Systems in High Energy Physics" (AHEP)
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1702.06312 [pdf]
    Adv.High Energy Phys.(2017)·5 citations
  2. 02

    [Submitted on 21 Feb 2017]

    Quartet correlations in N=Z nuclei induced by realistic two-body interactions

    M. Sambataro · N. Sandulescu

    Two variational quartet models previously employed in a treatment of pairing forces are extended to the case of a general two-body interaction. One model approximates the nuclear states as a condensate of identical quartets with angular momentum and isospin while the other let these quartets to be all different from each other. With these models we investigate the role of alpha-like quartet correlations both in the ground state and in the lowest , excited states of even-even nuclei in the -shell. We show that the ground state correlations of these nuclei can be described to a good extent in terms of a condensate of alpha-like quartets. This turns out to be especially the case for the nucleus S for which the overlap between this condensate and the shell model wave function is found close to one. In the same nucleus, a similar overlap is found also in the case of the first excited state. No clear correspondence is observed instead between the second excited states of the quartet models and the shell model eigenstates in all the cases examined.

    Comments:
    10 pages, to appear in EPJ A
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1702.06330 [pdf]
    EPJA(2017)·17 citations
  3. 03

    [Submitted on 21 Feb 2017]

    Seagull and pion-in-flight currents in neutrino-induced and knockout

    T. Van Cuyck🇧🇪 · N. Jachowicz🇧🇪 · R. González-Jiménez🇧🇪 · J. Ryckebusch🇧🇪 · N. Van Dessel🇧🇪

    [Background] The neutrino-nucleus () cross section is a major source of systematic uncertainty in neutrino-oscillation studies. A precise scattering model, in which multinucleon effects are incorporated, is pivotal for an accurate interpretation of the data. [Purpose] In interactions, meson-exchange currents (MECs) can induce two-nucleon () knockout from the target nucleus, resulting in a two-particle two-hole (2p2h) final state. They also affect single nucleon () knockout reactions, yielding a one-particle one-hole (1p1h) final state. Both channels affect the inclusive strength. We present a study of axial and vector, seagull and pion-in-flight currents in muon-neutrino induced and knockout reactions on C. [Method] Bound and emitted nucleons are described as Hartree-Fock wave functions. For the vector MECs, the standard expressions are used. For the axial current, three parameterizations are considered. The framework developed here allows for a treatment of MECs and short-range correlations (SRCs). [Results] Results are compared with electron-scattering data and with literature. The strengths of the seagull, pion-in-flight and axial currents are studied separately and double differential cross sections including MECs are compared with results including SRCs. A comparison with MiniBooNE and T2K data is presented. [Conclusions] In the 1p1h channel, the effects of the MECs tend to cancel each other, resulting in a small effect on the double differential cross section. knockout processes provide a small contribution to the inclusive double differential cross section, ranging from the knockout threshold into the dip region. A fair agreement with the MiniBooNE and T2K data is reached.

    Comments:
    16 pages, 10 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1702.06402 [pdf]
    PRC(2017)·47 citations
  4. 04

    [Submitted on 19 Feb 2017]

    A new two-component model for hadron production in heavy-ion collisions

    Xuejiao Yin🇨🇳 · Lilin Zhu🇨🇳 · Hua Zheng🇮🇹

    Using the experimental data from the ALICE program on the centrality dependence of the transverse momentum () spectra in Pb+Pb collisions at TeV, we show that the double-Tsallis distribution and the generalized Fokker-Plank (FP) solution can not describe the spectra of pions, kaons and protons from central to peripheral collisions in the entire region, simultaneously. Hence, a new two-component distribution, which is a hydrodynamic extension of the generalized FP solution accounting for the collective motion effect in heavy-ion collisions, is proposed in order to reproduce all the particle spectra. Our results suggest that the particle production dynamics may be different for different particles, especially at very low region.

    Comments:
    7 pages, 5 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1702.06415 [pdf]
    Adv.High Energy Phys.(2017)·11 citations
  5. 05

    [Submitted on 16 Feb 2017] (cross-list from hep-ph)

    Re-examining valence quark spin distributions

    A. I. Signal🇳🇿

    The observed deep inelastic nucleon spin asymmetries and the spin dependent quark distributions break SU(6) spin - flavour symmetry. In quark models two mechanisms for breaking SU(6) symmetry are well known: the hyperfine interaction and the pion cloud of the nucleon. I re-evaluate these mechanisms and show how the breaking of SU(6) in each case affects spin dependent valence quark distributions of the proton. In particular I investigate the properties of these mechanisms in the kinematic region and attempt to test these against known data. Both mechanisms are able to explain the quantitative features of the spin asymmetries.

    Comments:
    27 pages, 6 figures. Revised version accepted for publication in Physical Review D
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1702.05152 [pdf]
    PRD(2017)·3 citations
  6. 06

    [Submitted on 21 Feb 2017] (cross-list from hep-ph)

    Including resummation in the NLO BK equation

    T. Lappi🇫🇮 · H. Mäntysaari🇺🇸

    We include a resummation of large transverse momentum logarithms in the next-to-leading order (NLO) Balitsky-Kovchegov equation. The resummed evolution equation is shown to be stable, the evolution speed being significantly reduced by NLO corrections. The contributions from NLO terms that are not enhanced by large logarithms are found to be numerically important close to phenomenologically relevant initial conditions. We numerically determine the value for the constant in the resummed logarithm that includes a maximal part of the full NLO terms in the resummation.

    Comments:
    4 pages, 3 figures, talk by T.L. at Hard Probes 2016
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1702.06320 [pdf]
    Nucl.Part.Phys.Proc.(2017)·0 citations
  7. 07

    [Submitted on 21 Feb 2017] (cross-list from cond-mat.quant-gas)

    Universal behavior of few-boson systems using potential models

    A. Kievsky🇮🇹 · M. Viviani🇮🇹 · R. Álvarez-Rodrí guez🇪🇸 · M. Gattobigio🇫🇷 · A. Deltuva🇱🇹

    The universal behavior of a three-boson system close to the unitary limit is encoded in a simple dependence of many observables in terms of few parameters. For example the product of the three-body parameter and the two-body scattering length , depends on the angle defined by . A similar dependence is observed in the ratio with the boson-dimer scattering length. We use a two-parameter potential to determine this simple behavior and, as an application, to compute for the case of three He atoms.

    Comments:
    presented at the 23rd European Conference on Few-Body Problems in Physics
    Subjects:
    Quantum Gases (cond-mat.quant-gas); Nuclear Theory (nucl-th)
    arXiv:
    1702.06465 [pdf]
    Few Body Syst.(2017)·3 citations

Affiliations

first authorsco-authorsvia INSPIRE