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Nuclear Theory·nucl-th

Wednesday·July 19, 2017

10 papers—5 primary·5 cross-listed

All10Primary5Cross-lists5
  1. 01

    [Submitted on 17 Jul 2017]

    Proton emission with a screened electrostatic barrier

    R. Budaca · A. I. Budaca

    Half-lives of proton emission for Z51 nuclei are calculated within a simple analytical model based on the WKB approximation for the barrier penetration probability which includes the centrifugal and overlapping effects besides the electrostatic repulsion. The model has a single free parameter associated to a Hulthen potential which emulates a Coulomb electrostatic interaction only at short distance. The agreement with experimental data is very good for most of the considered nuclei. Theoretical predictions are made for few cases with uncertain emitting state configuration or incomplete decay information. The model's assignment of the proton orbital momentum is in agreement with the differentiation of the experimental data by orbital momentum values realized with a newly introduced correlation formula.

    Comments:
    8 pages, 3 figures, 2 tables, Accepted in Eur. Phys. J. A
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1707.05356 [pdf]
    EPJA(2017)·22 citations
  2. 02

    [Submitted on 18 Jul 2017]

    Estimating the Charm Quark Diffusion Coefficient and thermalization time from D meson spectra at RHIC and LHC

    Francesco Scardina🇮🇹 · Santosh K. Das🇮🇹 · Vincenzo Minissale🇮🇹 · Salvatore Plumari🇮🇹 · Vincenzo Greco🇮🇹

    We describe the propagation of charm quarks in the quark-gluon plasma (QGP) by means of a Boltzmann transport approach. Non-perturbative interaction between heavy quarks and light quarks have been taken into account through a quasi-particle approach in which light partons are dressed with thermal masses tuned to lQCD thermodynamics. Such a model is able to describe the main feature of the non-perturbative dynamics: the enhancement of the interaction strength near . We show that the resulting charm in-medium evolution is able to correctly predict simultaneously the nuclear suppression factor, , and the elliptic flow, , at both RHIC and LHC energies and at different centralities. The hadronization of charm quarks is described by mean of an hybrid model of fragmentation plus coalescence and plays a key role toward the agreeement with experimental data. We also performed calculations within the Langevin approach which can lead to very similar as Boltzmann, but the charm drag coefficient as to be reduced by about a and also generates an elliptic flow is about a smaller. We finally compare the space diffusion coefficient extracted by our phenomenological approach to lattice QCD results, finding a satisfying agreement within the present systematic uncertainties. Our analysis implies a charm thermalization time, in the limit, of about which is smaller than the QGP lifetime at LHC energy.

    Comments:
    13 pages, 12 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1707.05452 [pdf]
    PRC(2017)·199 citations
  3. 03

    [Submitted on 18 Jul 2017]

    Pion transverse-momentum spectrum and elliptic anisotropy of partially coherent source

    Peng Ru🇨🇳 · Ghulam Bary🇨🇳 · Wei-Ning Zhang🇨🇳

    In this letter, we study the pion momentum distribution of a coherent source and investigate the influences of coherent emission on the pion transverse-momentum () spectrum and elliptic anisotropy. With a partially coherent source, constructed by a conventional viscous hydrodynamics model (chaotic part) and a parameterized expanding coherent source model, we reproduce the pion spectrum and elliptic anisotropy coefficient in the peripheral Pb-Pb collisions at TeV. It is found that the influences of coherent emission on the pion spectrum and are related to the initial size and shape of the coherent source, largely due to the interference effect. However, the effect of source dynamical evolution on coherent emission is relatively small. The results of the partially coherent source with 33% coherent emission and 67% chaotic emission are consistent with the experimental measurements of the pion spectrum, , and especially four-pion Bose-Einstein correlations.

    Comments:
    8 pages, 4 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1707.05461 [pdf]
    PLB(2018)·6 citations
  4. 04

    [Submitted on 18 Jul 2017]

    Probing short-range correlations in asymmetric nuclei with quasi-free pair knockout reactions

    Sam Stevens · Jan Ryckebusch · Wim Cosyn · Andreas Waets

    Short-range correlations (SRC) in asymmetric nuclei with an unusual neutron-to-proton ratio can be studied with quasi-free two-nucleon knockout processes following the collision between accelerated ions and a proton target. We derive an approximate factorized cross section for those SRC-driven reactions. Our reaction model hinges on the factorization properties of SRC-driven reactions for which strong indications are found in theory-experiment comparisons. In order to put our model to the test we compare its predictions with results of measurements conducted at Brookhaven National Laboratory (BNL) and find a fair agreement. The model can also reproduce characteristic features of SRC-driven two-nucleon knockout reactions, like back-to-back emission of the correlated nucleons. We study the asymmetry dependence of nuclear SRC by providing predictions for the ratio of proton-proton to proton-neutron knockout cross sections for the carbon isotopes C thereby covering neutron excess values between -0.5 and +0.5.

    Comments:
    20 pages, 5 figures. Final version published in Physics Letters B, minor changes in the text
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1707.05542 [pdf]
    PLB(2018)·13 citations
  5. 05

    [Submitted on 18 Jul 2017]

    Multinucleon transfer dynamics in heavy-ion collisions near Coulomb barrier energies

    Fei Niu · Peng-Hui Chen · Ya-Fei Guo · Chun-Wang Ma · Zhao-Qing Feng

    The multinucleon transfer reactions near barrier energies has been investigated with a multistep model based on the dinuclear system (DNS) concept, in which the capture of two colliding nuclei, the transfer dynamics and the de-excitation process of primary fragments are described by the analytical formula, the diffusion theory and the statistical model, respectively. The nucleon transfer takes place after forming the DNS and is coupled to the dissipation of relative motion energy and angular momentum by solving a set of microscopically derived master equations within the potential energy surface. Specific reactions of Ca+Sn, Ca (Ar, Ni)+Th, Ca (Ni)+U and Ca (Ni) +Cm near barrier energies are investigated. It is found that the fragments are produced by the multinucleon transfer reactions with the maximal yields along the -stability line. The isospin relaxation is particularly significant in the process of fragment formation. The incident energy dependence of heavy target-like fragments in the reaction of Ni+Cm is analyzed thoroughly.

    Comments:
    9 pages, 9 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1707.05583 [pdf]
    PRC(2017)·13 citations

Affiliations

first authorsco-authorsvia INSPIRE