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Nuclear Theory·nucl-th

Monday·February 27, 2017

8 papers—4 primary·4 cross-listed

All8Primary4Cross-lists4
  1. 01

    The Glauber model and heavy ion reaction and elastic scattering cross sections

    Ajay Mehndiratta · Prashant Shukla

    We revisit the Glauber model to study the heavy ion reaction cross sections and elastic scattering angular distributions at low and intermediate energies. The Glauber model takes nucleon-nucleon cross sections and nuclear densities as inputs and has no free parameter and thus can predict the cross sections for unknown systems. The Glauber model works at low energies down to Coulomb barrier with very simple modifications. We present new parametrization of measured total cross sections as well as ratio of real to imaginary parts of the scattering amplitudes for pp and np collisions as a function of nucleon kinetic energy. The nuclear (charge) densities obtained by electron scattering form factors measured in large momentum transfer range are used in the calculations. The heavy ion reaction cross sections are calculated for light and heavy systems and are compared with available data measured over large energy range. The model gives excellent description of the data. The elastic scattering angular distributions are calculated for various systems at different energies. The model gives good description of the data at small momentum transfer but the calculations deviate from the data at large momentum transfer.

    nucl-thNPA(2017)·19 citations
  2. 02

    Weak Magnetism Correction to Allowed Beta-decay for Reactor Antineutrino Spectra

    X.B. Wang · A.C. Hayes

    The weak magnetism correction and its uncertainty to nuclear beta-decay play a major role in determining the significance of the reactor neutrino anomaly. Here we examine the common approximation used for one-body weak magnetism in the calculation of fission antineutrino spectra, wherein matrix elements of the orbital angular momentum operator contribution to the magnetic dipole current are assumed to be proportional to those of the spin operator. Although we find this approximation invalid for a large set of nuclear structure situations, we conclude that it is valid for the relevant allowed beta-decays between fission fragments. In particular, the uncertainty in the fission antineutrino due to the uncertainty in the one-body weak magnetism correction is found to be less than 1%. Thus, the dominant uncertainty from weak magnetism for reactor neutrino fluxes lies in the uncertainty in the two-body meson-exchange magnetic dipole current.

    nucl-thPRC(2017)·19 citations
  3. 03

    New approach to initializing hydrodynamic fields and mini-jet propagation in quark-gluon fluids

    Michito Okai🇯🇵 · Koji Kawaguchi🇯🇵 · Yasuki Tachibana🇨🇳 · Tetsufumi Hirano🇯🇵

    We propose a new approach to initialize the hydrodynamic fields such as energy density distributions and four flow velocity fields in hydrodynamic modeling of high-energy nuclear collisions at the collider energies. Instead of matching the energy-momentum tensor or putting the initial conditions of quark-gluon fluids at a fixed initial time, we utilize a framework of relativistic hydrodynamic equations with source terms to describe the initial stage. Putting the energy and momentum loss rate of the initial partons into the source terms, we obtain hydrodynamic initial conditions dynamically. The resultant initial profile of the quark-gluon fluid looks highly bumpy as seen in the conventional event-by-event initial conditions. In addition, initial random flow velocity fields also are generated as a consequence of momentum deposition from the initial partons. We regard the partons that survive after the dynamical initialization process as the mini-jets and find sizable effects of both mini-jet propagation in the quark-gluon fluids and initial random transverse flow on the final momentum spectra and anisotropic flow observables. We perform event-by-event -dimensional ideal hydrodynamic simulations with this new framework that enables us to describe the hydrodynamic bulk collectivity, parton energy loss, and interplay among them in a unified manner.

    nucl-thhep-phnucl-exPRC(2017)·60 citations
  4. 04

    Probing QCD critical fluctuations from light nuclei production in relativistic heavy-ion collisions

    Kai-Jia Sun🇨🇳 · Lie-Wen Chen🇨🇳 · Che Ming Ko🇺🇸 · Zhangbu Xu🇨🇳

    Based on the coalescence model for light nuclei production, we show that the yield ratio of , d, and H in heavy-ion collisions is sensitive to the neutron relative density fluctuation at kinetic freeze-out. From recent experimental data in central Pb+Pb collisions at ~GeV, ~GeV, ~GeV, ~GeV and ~GeV measured by the NA49 Collaboration at the CERN Super Proton Synchrotron (SPS), we find a possible non-monotonic behavior of as a function of the collision energy with a peak at ~GeV, indicating that the density fluctuations become the largest in collisions at this energy. With the known chemical freeze-out conditions determined from the statistical model fit to experimental data, we obtain a chemical freeze-out temperature of MeV and baryon chemical potential of MeV at this collision energy, which are close to the critical endpoint in the QCD phase diagram predicted by various theoretical studies. Our results thus suggest the potential usefulness of the yield ratio of light nuclei in relativistic heavy-ion collisions as a direct probe of the large density fluctuations associated with the QCD critical phenomena.

    nucl-thhep-phnucl-exPLB(2017)·136 citations

Affiliations

first authorsco-authorsvia INSPIRE