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Nuclear Theory·nucl-th

Thursday·September 27, 2018

7 papers—5 primary·2 cross-listed

All7Primary5Cross-lists2
  1. 01

    [Submitted on 25 Sept 2018]

    Evolution of the moments of multiplicity distributions

    Radka Sochorova🇨🇿 · Boris Tomasik🇨🇿 · Marcus Bleicher🇩🇪

    Measured moments of the multiplicity distribution for a given sort of particles are used in the literature for the determination of the phase transition parameters of hot QCD matter in ultrarelativistic heavy-ion collisions. We argue that the subsequent cooling in the hadronic phase, however, may drive the multiplicity distribution out of equilibrium. We use a master equation for the description of the evolution of the multiplicity distribution to demonstrate how the different moments depart away from their equilibrium values. If such moments were measured and interpreted as if they were equilibrated, one would obtain different apparent temperatures from different moments.

    Comments:
    8 pages, 7 figures, to be published in Physical Review C, in the updated version some references added, discussion extended and typos corrected
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1809.09653 [pdf]
    PRC(2018)·5 citations
  2. 02

    [Submitted on 25 Sept 2018]

    Representations of relativistic particles of arbitrary spin in Poincaré, Lorentz, and Euclidean covariant formulations of relativistic quantum mechanics

    W. N. Polyzou🇺🇸

    Relativistic treatments of quantum mechanical systems are important for understanding hadronic structure and dynamics at sub-nucleon distance scales. Hadronic states in different inertial reference frames are needed to compute current matrix elements that probe hadronic structure and dynamics. Relativistic invariance is an important consideration as the resolution of the probe is increased. Many different treatments of relativistic dynamics are used in practice, including Poincaré covariant methods, Lorentz covariant methods, Euclidean covariant methods and methods based on quantum fields. Wave functions are typically matrix elements of interacting relativistic states in a basis of non-interacting relativistic states. The purpose of this work is to develop the relation between these different representations of relativistic states that are used in different applications from a unified point of view, starting with positive mass irreducible representations of the Poincaré group.

    Comments:
    44 pages - revision includes new section on dynamics
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Theory (hep-th)
    arXiv:
    1809.09717 [pdf]
    PRC(2019)·9 citations
  3. 03

    [Submitted on 26 Sept 2018]

    Alleviating the inconsistencies in modelling decay of fissile compound nuclei

    Tathagata Banerjee · S. Nath · Santanu Pal

    This work attempts to overcome the existing inconsistencies in modelling decay of fissile nucleus by inclusion of important physical effects in the model and through a systematic analysis of a large set of data over a wide range of CN mass (ACN). The model includes shell effect in the level density (LD) parameter, shell correction in the fission barrier, effect of the orientation degree of freedom of the CN spin (Kor), collective enhancement of level density (CELD) and dissipation in fission. Input parameters are not tuned to reproduce observables from specific reaction(s) and the reduced dissipation coefficient is treated as the only adjustable parameter. Calculated evaporation residue (ER) cross sections, fission cross sections and particle, i.e. neutron, proton and alpha-particle, multiplicities are compared with data covering ACN = 156-248. The model produces reasonable fits to ER and fission excitation functions for all the reactions considered in this work. Pre-scission neutron multiplicities are underestimated by the calculation beyond ACN~200. An increasingly higher value of pre-saddle dissipation strength is required to reproduce the data with increasing ACN. Proton and alpha-particle multiplicities, measured in coincidence with both ERs and fission fragments, are in qualitative agreement with model predictions. The present work mitigates the existing inconsistencies in modelling statistical decay of the fissile CN to a large extent.

    Comments:
    15 pages, 9 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1809.09772 [pdf]
    PRC(2019)·24 citations
  4. 04

    [Submitted on 26 Sept 2018]

    Fully coupled-channel study of resonance in a chiral SU(3)-based potential

    Akinobu Doté🇯🇵 · Takashi Inoue🇯🇵 · Takayuki Myo🇯🇵

    Nuclear system with antikaons, so-called kaonic nuclei, has been a longstanding issue in strange nuclear physics and hadron physics, because they might have exotic nature; In particular, they could be a doorway to the dense matter due to the strong attraction between antikaon and nucleon. Among kaonic nuclei, the three-body system composed of two protons and a single meson, , is the most essential. In this article, we will report on the recent situation of studies in both theoretical and experimental sides. Afterwards, we will explain our latest study of the with a fully coupled-channel complex scaling method (Full ccCSM) using a chiral SU(3)-based (-) potential. In Full ccCSM, the is completely treated as a resonant state of a -- coupled-channel system. The energy dependence involved in the chiral potential is handled with a self-consistent calculation in which two extreme ansatzes are examined: field picture and particle picture. With our chiral SU(3)-based potential constrained by the precise data of kaonic hydrogen atom (SIDDHARTA experiment), the resonance is obtained as a shallowly bound state measured from the threshold with a narrow width, if the field picture is employed in the calculation: the binding energy is MeV and half value of the mesonic decay width are MeV. On the other hand, if the particle picture is employed, it is found that the binding energy could be as large as about 50 MeV, even though such a chiral potential is used. Based on these results of Full ccCSM calculation, we have discussed on the possibility for kaonic nuclei to form a dense matter and on the latest experimental result reported by J-PARC E15 collaboration.

    Comments:
    11 pages, 4 figures, 1 table, A plenary talk given at the 13th International Conference on Hypernuclear and Strange Particle Physics, June 24-29, 2018, Portsmouth, VA
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1809.09786 [pdf]
    AIP Conf.Proc.(2019)·1 citation
  5. 05

    [Submitted on 25 Sept 2018]

    Connection between asymptotic normalization coefficients and resonance widths of mirror states

    Akram Mukhamedzhanov

    Asymptotic normalization coefficients (ANCs) are fundamental nuclear constants playing important role in nuclear reactions, nuclear structure and nuclear astrophysics. In this paper a connection between ANCs and resonance widths of the mirror states is established. Using Pinkston-Satchler equation the ratio for resonance widths and ANCs of mirror nuclei is obtained in terms of the Wronskians from the radial overlap functions and regular solutions of the two-body Schrödinger equation with the short-range interaction excluded. This ratio allows one to use microscopic overlap functions for mirror nuclei in the internal region, where they are the most accurate, to correctly predict the ratio of the resonance widths and ANCs for mirror nuclei, which determine the amplitudes of the tails of the overlap functions. If the microscopic overlap functions are not available one can express the Wronskians for the resonances and mirror bound states in terms of the corresponding mirror two-body potential-model wave functions. A further simplification of the Wronskians ratio leads to the equation for the ratio of the resonance widths and mirror ANCs, which is expressed in terms of the ratio of the two-body Coulomb scattering wave functions at the resonance energy and at the binding energy [N. K. Timofeyuk, R. C. Johnson, and A. M. Mukhamedzhanov, Phys. Rev. Lett. {\bf 91}, 232501 (2003]. In this paper calculations of the ratios of resonance widths and mirror ANCs for different nuclei are presented. From this ratio one can determine the resonance width if the mirror ANC is known and vice versa. Comparison with available experimental ratios are done.

    Comments:
    19 pages, 10 figures. arXiv admin note: text overlap with arXiv:1209.2158
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1809.09980 [pdf]
    PRC(2019)·12 citations

Affiliations

first authorsco-authorsvia INSPIRE