PaperPanorama
FAQ

Nuclear Theory·nucl-th

Tuesday·January 10, 2017

14 papers—7 primary·7 cross-listed

All14Primary7Cross-lists7
  1. 01

    [Submitted on 7 Jan 2017]

    Revisit of directed flow in relativistic heavy-ion collisions from a multiphase transport model

    Chong-Qiang Guo🇨🇳 · Chun-Jian Zhang🇨🇳 · Jun Xu🇨🇳

    We have revisited several interesting questions on how the rapidity-odd directed flow is developed in relativistic Au+Au collisions at = 200 and 39 GeV based on a multiphase transport model. As the partonic phase evolves with time, the slope of the parton directed flow at midrapidity region changes from negative to positive as a result of the later dynamics at 200 GeV, while it remains negative at 39 GeV due to the shorter life time of the partonic phase. The directed flow splitting for various quark species due to their different initial eccentricities is observed at 39 GeV, while the splitting is very small at 200 GeV. From a dynamical coalescence algorithm with Wigner functions, we found that the directed flow of hadrons is a result of competition between the coalescence in momentum and coordinate space as well as further modifications by the hadronic rescatterings.

    Comments:
    8 pages, 8 figures, version after major revision
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex)
    arXiv:
    1701.01805 [pdf]
    EPJA(2017)·15 citations
  2. 02

    [Submitted on 8 Jan 2017]

    Analytical coalescence formula for particle production in relativistic heavy-ion collisions

    Kai-Jia Sun🇨🇳 · Lie-Wen Chen🇨🇳

    Based on a covariant coalescence model with a blast-wave-like parametrization for the phase-space configuration of constituent particles at freeze-out, we derive an approximate analytical formula for the yields of clusters produced in relativistic heavy-ion collisions. Compared to previous existing formulae, the present work additionally considers the contributions from the longitudinal dimension in momentum space, the relativistic corrections and the finite size effects of the produced clusters relative to the spatial distribution of constituent particles at freeze-out. The new analytical coalescence formula provides a useful tool to evaluate the yield of produced clusters, such as light nuclei from nucleon coalescence and hadrons from quark coalescence, in heavy-ion collisions. As a first application of the new analytical formula, we explore the strangeness population factor H/(Hep) based on nucleon/ coalescence as well as the production of exotic hadrons based on quark coalescence, in central Pb+Pb collisions at TeV. The results are compared with the predictions from other models.

    Comments:
    12 pages, 0 figures, 3 tables. Discussions added. Accepted version to appear in PRC
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1701.01935 [pdf]
    PRC(2017)·58 citations
  3. 03

    [Submitted on 9 Jan 2017]

    Microscopic dynamics simulations of multi-nucleon transfer in Kr+Ni at 25 MeV/nucleon

    Hong Yao · Ning Wang

    Multi-nucleon transfer in Kr+Ni at an incident energy of 25 MeV/nucleon is for the first time investigated with a microscopic dynamics model: improved quantum molecular dynamics (ImQMD) model. The measured isotope distributions are reasonably well reproduced by using the ImQMD model together with a statistical code (GEMINI) for describing the secondary decay of fragments. The reaction mechanism is explored with the microscopic dynamics simulations from central to peripheral collisions. In central collisions there exists a strong competition among fusion, deep-inelastic scattering and multi-fragmentation at such an incident energy. In semi-peripheral collisions, binary scattering together with nucleon transfer is dominant, and the probability of elastic+inelastic scattering events increases rapidly with impact parameter in peripheral collisions and approaches to one when fm. The mass-TKE distribution in central collisions due to the competition is quite different from those in peripheral collisions and the distribution of total kinetic energy loss (TKEL) for binary events with nucleon transfer is much more broader than those without transfer.

    Comments:
    9 figures, to appear in Phys. Rev. C
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1701.02082 [pdf]
    PRC(2017)·23 citations
  4. 04

    [Submitted on 9 Jan 2017]

    Observables for longitudinal flow correlations in heavy-ion collisions

    Jiangyong Jia🇺🇸 · Peng Huo🇺🇸 · Guoliang Ma🇨🇳 · Maowu Nie🇺🇸

    We propose several new observables/correlators, based on correlations between two or more subevents separated in pseudorapidity , to study the longitudinal flow fluctuations. We show that these observables are sensitive to the event-by-event fluctuations, as a function of , of the initial condition as well as the non-linear mode-mixing effects. Experimental measurement of these observables shall provide important new constraints on the boost-variant event-by-event initial conditions required by all 3+1-dimensional viscous hydrodynamics models.

    Comments:
    7 pages, 2 figures, a few typo corrected
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1701.02183 [pdf]
    J.Phys.G(2017)·33 citations
  5. 05

    [Submitted on 23 Dec 2016]

    Production of hypernuclei in antiproton - nucleus collisions

    R. Shyam🇮🇳 · K. Tsushima🇧🇷

    We investigate the production of charm-baryon hypernucleus O in the antiproton - O collisions within a fully covariant model that is based on an effective Lagrangian approach. The explicit production vertex is described by the -channel and meson-exchanges in the initial collision of the incident antiproton with one of the protons of the target nucleus. The bound state spinors as well as the self-energies of the exchanged mesons employed in our calculations are derived from the quark-meson coupling model. The parameters of various vertices are taken to be the same as those used in our previous study of the elementary reaction. We find that for antiproton beam momenta of interest to the experiment, the 0 differential cross sections for the formation of O hypernuclear states with simple particle-hole configurations, have magnitudes in the range of a few b/sr.

    Comments:
    17 pages, 5 figures, Journal print version
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1701.02225 [pdf]
    PLB(2017)·21 citations
  6. 06

    [Submitted on 9 Jan 2017]

    Charmonium spectrum and diffractive production in a light-front Hamiltonian approach

    Guangyao Chen🇺🇸 · Yang Li🇺🇸 · Pieter Maris🇺🇸 · Kirill Tuchin🇺🇸 · James P. Vary🇺🇸

    We study exclusive charmonium production in diffractive deep inelastic scattering and ultra-peripheral heavy-ion collisions within the dipole picture. The mass spectrum and light-front wavefunctions of charmonium are obtained from the basis light-front quantization approach, using the one-gluon exchange interaction plus a confining potential inspired by light-front holography. We apply these light-front wavefunctions to exclusive charmonium production. The resulting cross sections are in reasonable agreement with electron-proton collision data at HERA and ultra-peripheral nucleus collision measurements at RHIC and LHC. The charmonium cross-section has model dependence on the dipole model. We observe that the cross-section ratio of excited states to the ground state has a weaker dependence than the cross-section itself. We suggest that measurements of excited states of heavy quarkonium production in future electron-ion collision experiments will impose rigorous constraints on heavy quarkonium light-front wavefunctions, thus improving our understanding of meson structure, which eventually will help us develop a precise description of the gluon distribution function in the small- regime.

    Comments:
    4 pages, 4 figures, proceeding prepared for Hard Probes 2016
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1701.02279 [pdf]
    Nucl.Part.Phys.Proc.(2017)·2 citations
  7. 07

    [Submitted on 9 Jan 2017]

    Statistical model analysis of -induced reaction cross sections of Zn at low energies

    P. Mohr · Gy. Gyürky · Zs. Fülöp

    Background -nucleus potentials play an essential role for the calculation of -induced reaction cross sections at low energies in the statistical model. Uncertainties of these calculations are related to ambiguities in the adjustment of the potential parameters to experimental elastic scattering angular distributions (typically at higher energies) and to the energy dependence of the effective -nucleus potentials. Purpose The present work studies cross sections of -induced reactions for Zn at low energies and their dependence on the chosen input parameters of the statistical model calculations. The new experimental data from the recent Atomki experiments allow for a -based estimate of the uncertainties of calculated cross sections at very low energies. Method The recent data for the (,), (,), and (,) reactions on Zn are compared to calculations in the statistical model. A survey of the parameter space of the widely used computer code TALYS is given, and the properties of the obtained landscape are discussed. Results The best fit to the experimental data at low energies shows per data point which corresponds to an average deviation of about 30% between the best fit and the experimental data. Several combinations of the various ingredients of the statistical model are able to reach a reasonably small , not exceeding the best-fit result by more than a factor of 2. Conclusions The present experimental data for Zn in combination with the statistical model calculations allow to constrain the astrophysical reaction rate within about a factor of 2. However, the significant excess of of the best-fit from unity asks for further improvement of the statistical model calculations and in particular the -nucleus potential.

    Comments:
    10 pages, 3 figures, to appear in Phys. Rev. C
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1701.02290 [pdf]
    PRC(2017)·16 citations

Affiliations

first authorsco-authorsvia INSPIRE