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Nuclear Theory·nucl-th

Thursday·November 24, 2016

7 papers—4 primary·3 cross-listed

All7Primary4Cross-lists3
  1. 01

    [Submitted on 22 Nov 2016]

    Multi-neutron emission of Cd isotopes

    A. P. Severyukhin · N. N. Arsenyev · I. N. Borzov · E. O. Sushenok

    An influence of the phonon-phonon coupling (PPC) on the -decay half-lives and multi-neutron emission probabilities is analysed within the microscopic model based on the Skyrme interaction with tensor components included. The finite-rank separable approximation is used in order to handle large two-quasiparticle spaces. The even-even nuclei near the r-process pathes at are studied. The characteristics of ground states, excitations and -decay strength of the neutron-rich Cd isotopes are treated in detail. It is shown that a strong redistribution of the Gamow-Teller strength due to the PPC is mostly sensitive to the multi-neutron emission probability of the Cd isotopes.

    Comments:
    10 pages, 6 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1611.07542 [pdf]
    PRC(2017)·13 citations
  2. 02

    [Submitted on 22 Nov 2016]

    Geometrical Clusterization in SU(2) gluodynamics and Liquid-gas Phase Transition

    A. I. Ivanytskyi🇺🇦 · K. A. Bugaev🇺🇦 · V. V. Sagun🇺🇦 · D. R. Oliinychenko🇺🇦

    The liquid droplet formula is applied to an analysis of the properties of geometrical (anti)clusters formed in SU(2) gluodynamics by the Polyakov loops of the same sign. Using this approach, we explain the phase transition in SU(2) gluodynamics as a transition between two liquids during which one of the liquid droplets (the largest cluster of a certain Polyakov loop sign) experiences a condensation, while another droplet (the next to the largest cluster of the opposite sign of Polyakov loop) evaporates. The clusters of smaller sizes form two accompanying gases, which behave oppositely to their liquids. The liquid droplet formula is used to analyze the size distributions of the gas (anti)clusters. The fit of these distributions allows us to extract the temperature dependence of surface tension and the value of Fisher topological exponent for both kinds of gaseous clusters. It is shown that the surface tension coeficient of gaseous (anti)clusters can serve as an order parameter of the deconfinement phase transition in SU(2) gluodynamics. The Fisher topological exponent of (anti)clusters is found to have the same value . This value disagrees with the famous Fisher droplet model, but it agrees well with an exactly solvable model of nuclear liquid-gas phase transition. This finding may evidence for the fact that the SU(2) gluodynamics and this exactly solvable model of nuclear liquid-gas phase transition are in the same universality class.

    Comments:
    6 pages, 5 figures, proceedings of WDS 2016 Conference
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1611.07569 [pdf]
    0 citations
  3. 03

    [Submitted on 23 Nov 2016]

    Effective potential for relativistic scattering

    Mahmut Elbistan🇨🇳 · Pengming Zhang🇨🇳 · Janos Balog🇨🇳

    We consider quantum inverse scattering with singular potentials and calculate the Sine-Gordon model effective potential in the laboratory and centre-of-mass frames. The effective potentials are frame dependent but closely resemble the zero-momentum potential of the equivalent Ruijsenaars-Schneider model.

    Comments:
    23 pages, 5 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Theory (hep-th)
    arXiv:
    1611.07923 [pdf]
    PTEP(2017)·3 citations
  4. 04

    [Submitted on 23 Nov 2016]

    Structure of C and O nuclei within a five-cluster model

    B. E. Grinyuk · D. V. Piatnytskyi

    Within a five-particle model (three -particles plus two nucleons), the structure functions of mirror nuclei C and O are studied. Using the variational approach with Gaussian bases, the energies and wave functions are calculated for these five-particle systems. Two spatial configurations in the ground-state wave function are revealed. The r.m.s. charge radius of O nucleus is found to be fm. The charge density distributions and the form factors of both nuclei are predicted. The pair correlation functions are analyzed, and the r.m.s. relative distances are calculated. The momentum distributions of particles are found.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1611.07949 [pdf]
    0 citations
  5. 05

    [Submitted on 23 Nov 2016] (cross-list from hep-lat)

    On the Statistics of Baryon Correlation Functions in Lattice QCD

    Michael L. Wagman🇺🇸 · Martin J. Savage🇺🇸

    A systematic analysis of the structure of single-baryon correlation functions calculated with lattice QCD is performed, with a particular focus on characterizing the structure of the noise associated with quantum fluctuations. The signal-to-noise problem in these correlation functions is shown, as long suspected, to result from a sign problem. The log-magnitude and complex phase are found to be approximately described by normal and wrapped normal distributions respectively. Properties of circular statistics are used to understand the emergence of a large time noise region where standard energy measurements are unreliable. Power-law tails in the distribution of baryon correlation functions, associated with stable distributions and "Levy flights", are found to play a central role in their time evolution. A new method of analyzing correlation functions is considered for which the signal-to-noise ratio of energy measurements is constant, rather than exponentially degrading, with increasing source-sink separation time. This new method includes an additional systematic uncertainty that can be removed by performing an extrapolation, and the signal-to-noise problem re-emerges in the statistics of this extrapolation. It is demonstrated that this new method allows accurate results for the nucleon mass to be extracted from the large-time noise region inaccessible to standard methods. The observations presented here are expected to apply to quantum Monte Carlo calculations more generally. Similar methods to those introduced here may lead to practical improvements in analysis of noisier systems.

    Comments:
    34 pages, 35 figures. Discussion of systematic uncertainties and extrapolation in Sec. IV and elsewhere expanded and clarified. Notation adjusted for clarity
    Subjects:
    High Energy Physics — Lattice (hep-lat); Statistical Mechanics (cond-mat.stat-mech); Strongly Correlated Electrons (cond-mat.str-el); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1611.07643 [pdf]
    PRD(2017)·63 citations
  6. 06

    [Submitted on 23 Nov 2016] (cross-list from hep-ph)

    Initial conditions in AA and pA collisions

    T. Lappi🇫🇮

    A full understanding of the spacetime evolution of the QCD matter created in a heavy ion collision requires understanding the properties of the initial stages. In the weak coupling picture these are dominated by classical gluon fields, whose properties can also be studied via the scattering of dilute probes off a high energy hadron or nucleus. A particular challenge is understanding small systems, where LHC data is also showing signs of collective behavior. We discuss some recent results of on the initial matter production and thermalization in heavy ion collisions, in particular in the gluon saturation framework.

    Comments:
    10 pages, 4 figures, talk at the XII Quark Confinement and Hadron Spectrum Conference (CONF12)
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1611.07668 [pdf]
    EPJ Web Conf.(2017)·2 citations
  7. 07

    [Submitted on 23 Nov 2016] (cross-list from hep-ph)

    Neutrino-Nucleus Cross Sections for Oscillation Experiments

    Teppei Katori🇬🇧 · Marco Martini🇫🇷

    Neutrino oscillations physics is entered in the precision era. In this context accelerator-based neutrino experiments need a reduction of systematic errors to the level of a few percent. Today one of the most important sources of systematic errors are neutrino-nucleus cross sections which in the hundreds-MeV to few-GeV energy region are known with a precision not exceeding 20%. In this article we review the present experimental and theoretical knowledge of the neutrino-nucleus interaction physics. After introducing neutrino oscillation physics and accelerator-based neutrino experiments, we overview general aspects of the neutrino-nucleus cross sections, both theoretical and experimental views. Then we focus on these quantities in different reaction channels. We start with the quasielastic and quasielastic-like cross section, putting a special emphasis on multinucleon emission channel which attracted a lot of attention in the last few years. We review the main aspects of the different microscopic models for this channel by discussing analogies and differences among them.The discussion is always driven by a comparison with the experimental data. We then consider the one pion production channel where data-theory agreement remains very unsatisfactory. We describe how to interpret pion data, then we analyze in particular the puzzle related to the impossibility of theoretical models and Monte Carlo to simultaneously describe MiniBooNE and MINERvA experimental results. Inclusive cross sections are also discussed, as well as the comparison between the and cross sections, relevant for the CP violation experiments. The impact of the nuclear effects on the reconstruction of neutrino energy and on the determination of the neutrino oscillation parameters is reviewed. A window to the future is finally opened by discussing projects and efforts in future detectors, beams, and analysis.

    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1611.07770 [pdf]
    J.Phys.G(2018)·206 citations

Affiliations

first authorsco-authorsvia INSPIRE