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Nuclear Theory·nucl-th

Tuesday·November 3, 2015

12 papers—7 primary·5 cross-listed

All12Primary7Cross-lists5
  1. 01

    [Submitted on 30 Oct 2015]

    Observables of non-equilibrium phase transition

    Boris Tomasik🇸🇰 · Martin Schulc🇨🇿 · Ivan Melo🇸🇰 · Renata Kopecna🇨🇿

    A rapidly expanding fireball which undergoes first-order phase transition will supercool and proceed via spinodal decomposition. Hadrons are produced from the individual fragments as well as the left-over matter filling the space between them. Emission from fragments should be visible in rapidity correlations, particularly of protons. In addition to that, even within narrow centrality classes, rapidity distributions will be fluctuating from one event to another in case of fragmentation. This can be identified with the help of Kolmogorov-Smirnov test. Finally, we present a method which allows to sort events with varying rapidity distributions in such a way, that events with similar rapidity histograms are grouped together.

    Comments:
    contribution to NICA white paper, 5 pages, revised version with minor corrections, mainly language
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1511.00034 [pdf]
    EPJA(2016)·1 citation
  2. 02

    [Submitted on 31 Oct 2015]

    Nuclear Matrix Elements for Double-Beta Decay

    Jonathan Engel🇺🇸

    Recent progress in nuclear-structure theory has been dramatic. I describe recent and future applications of ab initio calculations and the generator coordinate method to double-beta decay. I also briefly discuss the old and vexing problem of the renormalization of the weak nuclear axial-vector coupling constant "in medium" and plans to resolve it.

    Comments:
    Talk presented CIPANP2015. 8 pages, 4 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1511.00074 [pdf]
    0 citations
  3. 03

    [Submitted on 1 Nov 2015]

    Multi-Nucleon Exchange in Quasi-Fission Reactions

    S. Ayik · B. Yilmaz · O. Yilmaz

    Nucleon exchange mechanism is investigated in the central collisions of Ca + U and Ca + U systems near the quasi-fission regime in the framework of the Stochastic Mean-Field (SMF) approach. Sufficiently below the fusion barrier, di-nuclear structure in the collisions is maintained to a large extend. Consequently, it is possible to describe nucleon exchange as a diffusion process familiar from deep-inelastic collisions. Diffusion coefficients for proton and neutron exchange are determined from the microscopic basis of the SMF approach in the semi-classical framework. Calculations show that after a fast charge equilibration the system drifts toward symmetry over a very long interaction time. Large dispersions of proton and neutron distributions of the produced fragments indicate that diffusion mechanism may help to populate heavy trans-uranium elements near the quasi-fission regime in these collisions.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1511.00211 [pdf]
    PRC(2015)·27 citations
  4. 04

    [Submitted on 1 Nov 2015]

    Light-quark baryon spectroscopy from ANL-Osaka dynamical coupled-channels analysis

    Hiroyuki Kamano🇯🇵

    We review our recent efforts for determining resonance parameters associated with light-quark baryons (, , , ) through comprehensive analyses of various meson production reactions off the nucleon within the ANL-Osaka dynamical coupled-channels approach.

    Comments:
    10 pages, 11 figures. Plenary talk at The 10th International Workshop on the Physics of Excited Nucleons (NSTAR2015), Osaka, Japan, May 25-28, 2015
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1511.00252 [pdf]
    JPS Conf.Proc.(2016)·1 citation
  5. 05

    [Submitted on 1 Nov 2015]

    The heat capacity of the neutron star inner crust within an extended NSE model

    S. Burrello🇮🇹 · F. Gulminelli🇫🇷 · F. Aymard🇫🇷 · M.Colonna🇮🇹 · Ad.R.Raduta

    Superfluidity in the crust is a key ingredient for the cooling properties of proto-neutron stars. Present theoretical calculations employ the quasi-particle mean-field Hartree-Fock-Bogoliubov theory with temperature dependent occupation numbers for the quasi-particle states. Finite temperature stellar matter is characterized by a whole distribution of different nuclear species. We want to assess the importance of this distribution on the calculation of heat capacity in the inner crust. Following a recent work, the Wigner-Seitz cell is mapped into a model with cluster degrees of freedom. The finite temperature distribution is then given by a statistical collection of Wigner-Seitz cells. We additionally introduce pairing correlations in the local density BCS approximation both in the homogeneous unbound neutron component, and in the interface region between clusters and neutrons. The heat capacity is calculated in the different baryonic density conditions corresponding to the inner crust, and in a temperature range varying from 100 KeV to 2 MeV. We show that accounting for the cluster distribution has a small effect at intermediate densities, but it considerably affects the heat capacity both close to the outer crust and close to the core. We additionally show that it is very important to consider the temperature evolution of the proton fraction for a quantitatively reliable estimation of the heat capacity.

    Comments:
    13 pages, 11 figures, accepted for publication in PRC
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1511.00304 [pdf]
    PRC(2015)·33 citations
  6. 06

    [Submitted on 2 Nov 2015]

    Closed analytical solutions of the d-dimensional Schrödinger equation with deformed Woods-Saxon potential plus double ring-shaped potential

    M.Chabab · A. El Batoul · M. Oulne

    By employing the Pekeris approximation, the D-dimensional Schrödinger equation is solved for the nuclear deformed Woods-Saxon potential plus double ring-shaped potential within the framework of the Asymptotic Iteration Method (AIM). The energy eingenvalues are given in a closed form and the corresponding normalized eigenfunctions are obtained in terms of hypergeometric functions. Our general results reproduce many predictions obtained in the literature, using the Nikiforov-Uvarov method (NU) and the Improved Quantization Rule approach, particulary those derived by considering Woods-Saxon potential without deformation and/or without ring shape interaction.

    Comments:
    17 pages, Latex, accepted in Zeitschrift für Naturforschung A (ZNA), 2015
    Subjects:
    Nuclear Theory (nucl-th); Mathematical Physics (math-ph); math.MP (math.MP); Quantum Physics (quant-ph)
    arXiv:
    1511.00484 [pdf]
    Z.Naturforsch.A(2016)·6 citations
  7. 07

    [Submitted on 2 Nov 2015]

    Assessing Theory Uncertainties in EFT Power Countings from Residual Cutoff Dependence

    Harald W. Griesshammer (George Washington U.)🇺🇸

    I summarise a method to quantitatively assess the consistency of power-counting proposals in Effective Field Theories which are non-perturbative at leading order. It uses the fact that the Renormalisation Group evolution of an observable predicts the functional form of its residual cutoff dependence on the EFT breakdown scale, low-momentum scales, and the order of the calculation. Passing this test is a necessary but not sufficient consistency criterion for a suggested power counting whose exact nature is disputed. For example, in ChiEFT with more than one nucleon, a lack of universally accepted analytic solutions obfuscates the relation between convergence pattern and numerical results, and led to proposals which predict different numbers of Low Energy Coefficients at the same chiral order. The method may provide an independent check whether an observable is renormalised at a given order, and of both the breakdown scale and the momentum-dependent order-by-order convergence pattern of an EFT. Conversely, it may help identify LECs which produce renormalised observables at a given order. I also discuss its underlying assumptions and relation to the RG Equation; useful choices for observables and cutoffs; the momentum window in which the test provides best signals; its dependence on the values and forms of cutoffs as well as on the EFT parameters; the impact of fitting Low Energy Coefficients to data in different or the same channel; caveats and limitations. Since the test is designed to minimise the use of data, it allows one to quantitatively falsify if the EFT has been renormalised consistently, rather than quantifying how an EFT compares to experiment. Its application in particular to the 3P0 and 3P2-3F2 partial waves of NN scattering in ChiEFT may elucidate persistent power-counting issues. Details and a better bibliography can be found in an upcoming publication.

    Comments:
    14 pages LaTeX2e (pdflatex) including 5 figures as .pdf files using PoS.cls. Presented at the 8th International Workshop on Chiral Dynamics, CD2015, 29 June - 3 July 2015, Pisa, Italy; accepted for publication in the proceedings: PoS(CD15)104. Revision: substantial expansion with clarifications and addition of comments, minor corrections; conclusions unchanged
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1511.00490 [pdf]
    PoS(2016)·20 citations

Affiliations

first authorsco-authorsvia INSPIRE