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Nuclear Theory·nucl-th

Wednesday·February 21, 2018

12 papers—7 primary·5 cross-listed

All12Primary7Cross-lists5
  1. 01

    [Submitted on 19 Feb 2018]

    Theoretical analysis on the reaction for the bound-state search in the J-PARC E15 experiment

    Takayasu Sekihara (1) · Eulogio Oset (2) · Angels Ramos (3) ((1) JAEA, Ibaraki, (2) Valencia U. & Valencia U., IFIC, (3) Barcelona U. & ICC, Barcelona U.)

    We theoretically analyze the reaction for the bound-state search in the J-PARC E15 experiment. We find that, by detecting a fast and forward neutron in the final state, an almost on-shell is guaranteed, which is essential to make a bound state with two nucleons from . Then, this almost on-shell can bring a signal of the bound state in the invariant-mass spectrum, although it inevitably brings a kinematic peak above the threshold as well. As a consequence, we predict two peaks across the threshold in the spectrum: the lower peak coming from the bound state, and the higher one originating from the kinematics.

    Comments:
    4 pages, 4 EPS figures, talk given at XVII International Conference on Hadron Spectroscopy and Structure (Hadron2017), Salamanca, Spain, 25-29 September, 2017
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1802.06781 [pdf]
    PoS(2018)·4 citations
  2. 02

    [Submitted on 19 Feb 2018]

    Azimuthal Anisotropies at High Momentum from Purely Non-Hydrodynamic Transport

    Paul Romatschke🇺🇸

    In the limit of short mean free path, relativistic kinetic theory gives rise to hydrodynamics through a systematically improvable gradient expansion. In the present work, a systematically improvable expansion in the opposite limit of large mean free path is considered, describing the dynamics of particles which are almost, but not quite, non-interacting. This non-hydrodynamic "eremitic" expansion does not break down for large gradients, and may be useful in situations where a hydrodynamic treatment is not applicable. As applications, azimuthal anisotropies at high transverse momentum in Pb+Pb and p+Pb collisions at TeV are calculated from the first order eremitic expansion of kinetic theory in the relaxation time approximation.

    Comments:
    26 pages, 5 figures; v2: reference to Borghini and Gombeaud added who discussed same setup in 2010, typos corrected; v3: minor changes, matches published version
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1802.06804 [pdf]
    EPJC(2018)·42 citations
  3. 03

    [Submitted on 20 Feb 2018]

    Rotational motion of triaxially deformed nuclei studied by microscopic angular-momentum-projection method I: Nuclear wobbling motion

    Mitsuhiro Shimada · Yudai Fujioka · Shingo Tagami · Yoshifumi R. Shimizu

    Rotation of triaxially deformed nucleus has been an interesting subject in the study of nuclear structure. In the present series of work, we investigate wobbling motion and chiral rotation by employing the microscopic framework of angular-momentum projection from cranked triaxially deformed mean-field states. In this first part the wobbling motion is studied in detail. The consequences of the three dimensional cranking are investigated. It is demonstrated that the multiple wobbling rotational bands naturally appear as a result of fully microscopic calculation. They have the characteristic properties, that are expected from the macroscopic triaxial-rotor model or the phenomenological particle-triaxial-rotor model, although quantitative agreement with the existing data is not achieved. It is also found that the excitation spectrum reflects dynamics of the angular-momentum vector in the intrinsic frame of the mean-field (transverse vs. longitudinal wobbling). The results obtained by using the Woods-Saxon potential and the schematic separable interaction are mainly discussed, while some results with the Gogny D1S interaction are also presented.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1802.06988 [pdf]
    PRC(2018)·19 citations
  4. 04

    [Submitted on 20 Feb 2018]

    Rotational motion of triaxially deformed nuclei studied by microscopic angular-momentum-projection method II: Chiral doublet band

    Mitsuhiro Shimada · Yudai Fujioka · Shingo Tagami · Yoshifumi R. Shimizu

    In the sequel of the present study, we have investigated the rotational motion of triaxially deformed nucleus by using the microscopic framework of angular-momentum projection. The Woods-Saxon potential and the schematic separable-type interaction are employed as a microscopic Hamiltonian. As the first example nuclear wobbling motion was studied in detail in the part~I of the series. This second part reports on another interesting rotational mode, chiral doublet bands: two prototype examples, Cs and Rh, are investigated. It is demonstrated that the doublet bands naturally appear as a result of the calculation in this fully microscopic framework without any kind of core, and they have the characteristic properties of the and transition probabilities, which are expected from the phenomenological triaxial particle-rotor coupling model.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1802.06991 [pdf]
    PRC(2018)·22 citations
  5. 05

    [Submitted on 20 Feb 2018]

    First-order derivative of cluster size as a new signature of phase transition in heavy ion collisions at intermediate energies

    P. Das🇮🇳 · S. Mallik🇮🇳 · G. Chaudhuri🇮🇳

    The phenomenon of liquid-gas phase transition occurring in heavy ion collisions at intermediate energies is a subject of contemporary interest. Phase transition is usually characterized by the specific behaviour of state variables like pressure, density, energy etc. In heavy ion collisions there is no direct way of accessing these state variables and hence unambiguous detection of phase transition becomes difficult. This work establishes that signatures of phase transition can be extracted from the observables which are easily accessible in experiments and these have similar behaviour as the state variables. The temperature dependence of the first order derivative of the order parameters related to the largest and second largest cluster size (produced in heavy ion collisions) exhibit similar behavior as that of the variation of specific heat at constant volume Cv which is an established signature of first order phase transition. This motivates us to propose these derivatives as confirmatory signals of liquid-gas phase transition. The measurement of these signals in easily feasible in most experiments as compared to the other signatures like specific heat, caloric curve or bimodality. This temperature where the peak appears is designated to be the transition temperature and the effect of certain parameters on this has also been examined.

    Comments:
    5 pages, 4 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1802.07020 [pdf]
    PLB(2018)·11 citations
  6. 06

    [Submitted on 20 Feb 2018]

    A geometry for the shell model

    P. Van Isacker🇫🇷

    A geometric interpretation is given of matrix elements of a short-range interaction between states that are written in terms of aligned neutron-proton pairs.

    Comments:
    8 pages, 3 figures, conference CGS16
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1802.07025 [pdf]
    EPJ Web Conf.(2018)·3 citations
  7. 07

    [Submitted on 17 Feb 2018]

    Unitary Scheme Model Calculations of the Ground- and Excited-State Characteristics of 3H and 4He

    S. B. Doma · H. S. El-Gendy

    The ground and excited states of the 3H and 4He nuclei are studied in the framework of group-theoretical methods. Basis functions of the unitary scheme model corresponding to even numbers of quanta of excitation in the range from zero to twenty are constructed for the even-parity states of these two nuclei, and bases from one to nineteen are constructed for the odd-parity states of the 4He nucleus. The ground-state and first-excited-state energies and wave functions, the ground S-, P- and D-state probabilities, the root-mean-square radius and the magnetic dipole moment of Triton are calculated. Furthermore, for the 4He nucleus, the spectrum and the wave functions, the ground S-, P- and D-state probabilities, the root-mean-square radius and the total integral cross section of the dipole electric transition accompanying the photoabsorption of gamma quanta by this nucleus are calculated. The GPT and AV8' two-body interactions and the Urbana nine three-nucleon interaction are used in these investigations. Moreover, the convergence of the calculations is examined by incrementally extrapolating the nuclear characteristics calculated for N less than or equal to twenty to N equals thirty.

    Comments:
    15 pages. arXiv admin note: substantial text overlap with arXiv:1607.04810
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1802.07183 [pdf]
    J.Phys.Comm.(2018)·1 citation

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first authorsco-authorsvia INSPIRE