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Nuclear Theory·nucl-th

Friday·January 27, 2017

7 papers—3 primary·4 cross-listed

All7Primary3Cross-lists4
  1. 01

    [Submitted on 26 Jan 2017]

    Kubo formulae for the shear and bulk viscosity relaxation times and the scalar field theory shear calculation

    Alina Czajka🇨🇦 · Sangyong Jeon🇨🇦

    In this paper we provide a quantum field theoretical study on the shear and bulk relaxation times. First, we find Kubo formulas for the shear and the bulk relaxation times, respectively. They are found by examining response functions of the stress-energy tensor. We use general properties of correlation functions and the gravitational Ward identity to parametrize analytical structures of the Green functions describing both sound and diffusion mode. We find that the hydrodynamic limits of the real parts of the respective energy-momentum tensor correlation functions provide us with the method of computing both the shear and bulk viscosity relaxation times. Next, we calculate the shear viscosity relaxation time using the diagrammatic approach in the Keldysh basis for the massless theory. We derive a respective integral equation which enables us to compute and then we extract the shear relaxation time. The relaxation time is shown to be inversely related to the thermal width as it should be.

    Comments:
    version published in PRC, one equation and one figure added, some comments added
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1701.07580 [pdf]
    PRC(2017)·41 citations
  2. 02

    [Submitted on 26 Jan 2017]

    Few-body approach to structure of -nuclear quasi-bound states

    Shota Ohnishi🇯🇵 · Wataru Horiuchi🇯🇵 · Tsubasa Hoshino🇯🇵 · Kenta Miyahara🇯🇵 · Tetsuo Hyodo🇯🇵

    Structure of light antikaon-nuclear quasi-bound states, which consist of an antikaon and a few nucleons such as , , and systems, is studied with full three- to seven-body calculations. Employing a realistic potential based on the chiral SU(3) effective field theory with the SIDDHARTA constraint, we show that the central nucleon densities of these systems increases when the antikaon is injected, by about factor of two at maximum. The system shows the largest central density, about 0.74 fm even with the phenomenological potential, which are not as high as those suggested in previous studies with approximate treatments of the few-body systems. We find the spin of the ground state of the system depends on the strength of the attraction. Thus, the quantum number of the ground state can be another constraint on the interaction.

    Comments:
    22 pages, 17 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1701.07589 [pdf]
    PRC(2017)·43 citations
  3. 03

    [Submitted on 26 Jan 2017]

    Ab initio calculations for non-strange and strange few-baryon systems

    Winfried Leidemann🇮🇹

    Concerning the non-strange particle systems the low-energy excitation spectra of the three- and four-body helium isotopes are studied. Objects of the study are the astrophysical -factor of the radiative proton deuteron capture He and the width of the He isoscalar monopole resonance.Both observables are calculated using the Lorentz integral transform (LIT) method. The LIT equations are solved via expansions of the LIT states on a specifically modified hyperspherical harmonics (HH) basis. It is illustrated that at low energies such a modification allows to work with much higher LIT resolutions than with an unmodified HH basis. It is discussed that this opens up the possibility to determine astrophysical -factors as well as the width of low-lying resonances with the LIT method. In the sector of strange baryon systems binding energies of the hypernucleus H are calculated using a nonsymmetrized HH basis. The results are compared with those calculated by various other groups with different methods. For all the considered non-strange and strange baryon systems it is shown that high-precision results are obtained.

    Comments:
    15 pages, 5 figures, invited talk at the TNPI2016
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1701.07659 [pdf]
    J.Phys.Conf.Ser.(2018)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE