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Nuclear Theory·nucl-th

Friday·May 13, 2016

8 papers—6 primary·2 cross-listed

All8Primary6Cross-lists2
  1. 01

    [Submitted on 12 May 2016]

    Effects of the high-momentum tail of nucleon momentum distribution on the isospin-sensitive observables

    Fang Zhang · Gao-Chan Yong

    Based on the Isospin-dependent transport model Boltzmann-Uehling-Uhlenbeck (IBUU), effects of the high momentum tail (HMT) of nucleon momentum distribution in colliding nuclei on some isospin-sensitive observables are studied in the semi-central reactions at incident beam energy of 400 MeV/nucleon. It is found that the nucleon transverse flow, the difference of neutron and proton transverse flows, the nucleon elliptic flow and free neutron to proton ratio are all less sensitive to the HMT, while the isospin-sensitive nucleon elliptic flow difference is clearly affected by the HMT. Except at very high kinetic energies, the kinetic energy distributions of , and charged pion ratio are all sensitive to the HMT.

    Comments:
    6 pages, 6 figures, to appear in Eur. Phys. J. A
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1605.03656 [pdf]
    EPJA(2016)·14 citations
  2. 02

    [Submitted on 12 May 2016]

    Three nucleon forces in nuclear matter in the QCD sum rules

    E. G. Drukarev🇷🇺 · M. G. Ryskin🇷🇺 · V. A. Sadovnikova🇷🇺

    We calculate the single-particle nucleon characteristics in symmetric nuclear matter with inclusion of the 3N interactions. The contribution of the 3N forces to the nucleon self energies are expressed in terms of the nonlocal scalar condensate (d=3) and of the configuration of the two four-quark condensates (d=6) in which two diquark operators act on two different nucleons of the matter. The most important part of the contribution of the four-quark condensate is calculated in a model-independent way. We employed a relativistic quark model of nucleon for calculation of the rest part. The density dependence of the vector and scalar nucleon self energies and of the single-particle potential energy are obtained.

    Comments:
    21 pages, 7 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1605.03699 [pdf]
    NPA(2017)·7 citations
  3. 03

    [Submitted on 12 May 2016]

    Effects of symmetry energy in reaction at 300 MeV/nucleon

    Shan-Jing Cheng🇨🇳 · Gao-Chan Yong🇨🇳 · De-Hua Wen🇨🇳

    Based on the recently updated Isospin-dependent Boltzmann-Uehling-Uhlenbeck (IBUU) transport model, we studied the effects of symmetry energy on the neutron to proton n/p ratio and the ratio in central reaction at 300 MeV/nucleon. It is found that the n/p ratio and the ratio in central reaction at 300 MeV/nucleon mainly probe the symmetry energy in the density region 1-1.5 times saturation density. However, the ratio may be able to probe the density-dependent symmetry energy above 1.5 times saturation density by making some kinematic restrictions such as the azimuthal angle and kinetic energy cuts of emitting pions.

    Comments:
    7 pages, 8 figures, accepted version of PRC
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1605.03701 [pdf]
    PRC(2016)·13 citations
  4. 04

    [Submitted on 12 May 2016]

    The chiral S=-1 meson-baryon interaction with new constrains on the NLO contributions

    A. Ramos🇪🇸 · A. Feijoo🇪🇸 · V.K. Magas🇪🇸

    We present a study of the meson-baryon interaction, employing a chiral SU(3) Lagrangian up to next-to-leading order (NLO) and implementing unitarization in coupled channels. The parameters of the model have been fitted to a large set of experimental scattering data in different two-body channels, to threshold branching ratios, and to the precise SIDDHARTA value of the energy shift and width of kaonic hidrogen. In contrast to other groups, we have taken into consideration the reaction data, since we found in a previous work to be especially sensitive to the NLO parameters of the chiral Lagrangian. In the present work we also include the Born terms, which usually have very little effect, and find them to be non-negligible in the channels, correspondingly causing significant modifications to the NLO parameters. We furthermore show that the importance of the Born terms becomes more visible in the isospin projected amplitudes of the reactions. The measurement of processes that filter single isospin components, like the reaction that could be measured at the proposed secondary beam at Jlab, would put valuable constraints on the chiral models describing the meson-baryon interaction in the sector.

    Comments:
    21 pages, 6 figures. Accepted for publication in Nuclear Physics A (special issue on Strangeness and Charm Nuclear Physics). arXiv admin note: text overlap with arXiv:1502.07956
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1605.03767 [pdf]
    NPA(2016)·31 citations
  5. 05

    [Submitted on 12 May 2016]

    Description of light nuclei in pionless effective field theory using the stochastic variational method

    Vadim Lensky🇩🇪 · Michael C. Birse🇬🇧 · Niels R. Walet🇬🇧

    We construct a coordinate-space potential based on pionless effective field theory with a Gaussian regulator. Charge-symmetry breaking is included through the Coulomb potential and through two- and three-body contact interactions. Starting with the effective field theory potential, we apply the stochastic variational method to determine the ground states of nuclei with mass number . At next-to-next-to-leading order, two out of three independent three-body parameters can be fitted to the three-body binding energies. To fix the remaining one, we look for a simultaneous description of the binding energy of He and the charge radii of He and He. We show that at the order considered we can find an acceptable solution, within the uncertainty of the expansion. We find that the EFT expansion shows good agreement with empirical data within the estimated uncertainty, even for a system as dense as He.

    Comments:
    32 pages, 9 figures, RevTeX 4.1, minor corrections, one reference added, matches published version
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1605.03898 [pdf]
    PRC(2016)·20 citations
  6. 06

    [Submitted on 12 May 2016]

    Applying Bayesian parameter estimation to relativistic heavy-ion collisions: simultaneous characterization of the initial state and quark-gluon plasma medium

    Jonah E. Bernhard🇺🇸 · J. Scott Moreland🇺🇸 · Steffen A. Bass🇺🇸 · Jia Liu🇺🇸 · Ulrich Heinz🇺🇸

    We quantitatively estimate properties of the quark-gluon plasma created in ultra-relativistic heavy-ion collisions utilizing Bayesian statistics and a multi-parameter model-to-data comparison. The study is performed using a recently developed parametric initial condition model, TRENTO, which interpolates among a general class of particle production schemes, and a modern hybrid model which couples viscous hydrodynamics to a hadronic cascade. We calibrate the model to multiplicity, transverse momentum, and flow data and report constraints on the parametrized initial conditions and the temperature-dependent transport coefficients of the quark-gluon plasma. We show that initial entropy deposition is consistent with a saturation-based picture, extract a relation between the minimum value and slope of the temperature-dependent specific shear viscosity, and find a clear signal for a nonzero bulk viscosity.

    Comments:
    19 pages, 11 figures. This version includes minor clarifications in the description of the model and several updated references
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1605.03954 [pdf]
    PRC(2016)·595 citations

Affiliations

first authorsco-authorsvia INSPIRE