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Nuclear Theory·nucl-th

Tuesday·April 30, 2019

14 papers—7 primary·7 cross-listed

All14Primary7Cross-lists7
  1. 01

    Possible chiral doublets in Ni

    J. Peng🇨🇳 · Q. B. Chen🇩🇪

    The open problem on whether or not the chirality exists in doublet bands M1 and M4 in light-mass even-even nucleus Ni is studied by adopting the recently developed fully quantal four- shells triaxial particle rotor model. The corresponding experimental energy spectra, energy differences between doublet bands, and the available values are successfully reproduced. The analyses on the basis of the angular momentum components, the azimuthal plots, and the -plots suggest that the chiral modes exist at in doublet bands M1 and M4.

    nucl-thnucl-exPLB(2019)·20 citations
  2. 02

    Direct capture cross section of Be(n,)Be

    Peter Mohr

    The cross section of the Be(n,)Be reaction was calculated in the direct capture model. All parameters of the calculations were adjusted to properties of the Be + n system at thermal energies. The calculated cross section at thermonuclear energies shows the expected behavior of -wave capture at low energies, but increases towards higher energies as typical -wave capture. Excellent agreement between new experimental data in the astrophysically relevant energy region and the present calculation is found.

    nucl-thPRC(2019)·3 citations
  3. 03

    Emergence of nuclear clustering in electric-dipole excitations of Li

    S. Satsuka · W. Horiuchi

    Nuclear clustering plays an important role, especially in the dynamics of light nuclei. The importance of the emergence of the nuclear clustering was discussed in the recent measurement of the photoabsorption cross sections as it offered the possibility of the coexistence of various excitation modes which are closely related to the nuclear clustering. To understand the excitation mechanism, we study the electric-dipole () responses of Li with a fully microscopic six-body calculation. The ground-state wave function is accurately described with a superposition of correlated Gaussian (CG) functions with the aid of the stochastic variational method. The final-state wave functions are also expressed by a number of the CG functions including important configurations to describe the six-body continuum states excited by the field. We found that the out-of-phase transitions occur due to the oscillations of the valence nucleons against the He cluster at the low energies around 10 MeV indicating ``soft'' giant-dipole-resonance(GDR)-type excitations, which are very unique in the Li system but could be found in other nuclear systems. At the high energies beyond MeV typical GDR-type transitions occur. The He-H clustering plays an important role to the GDR phenomena in the intermediate energy regions around 20 MeV.

    nucl-thPRC(2019)·11 citations
  4. 04

    Implementation of the 8-Nucleon Yakubovsky Formalism for Halo Nucleus 8He

    Eskandar Ahmadi Pouya · Ali Akbar Rajabi

    In order to study the bound-state structure of the Helium halo nuclei, the 8-nucleon Yakubovsky formalism has been implemented for 8He in a 5-body sub-cluster model, i.e. alpha+n+n+n+n. In this case, the 8-nucleon Yakubovsky equations has been obtained in the form of two coupled equations, based on the two independent components. In addition, by removing the contribution interactions of the 8 and 7s bound nucleons in the formalism, the obtained equations explicitly reduce to the 6-nucleon Yakubovsky equations for 6He, in the case of effective 3-body model, i.e. alpha+n+n. In view of the expectation for the dominant structure of 8He, namely an inert alpha-core and four loosely-bound neutrons, Jacobi configurations of the two components in momentum space have been represented to provide technicalities which were considered useful for a numerical performance, such as bound-state calculations and momentum density distributions for halo-bound neutrons.

    nucl-th0 citations
  5. 05

    Quark matter symmetry energy effect on equation of state for neutron stars

    Xuhao Wu🇨🇳 · Akira Ohnishi🇯🇵 · Hong Shen🇨🇳

    We study the equation of state of neutron-star matter including the effects of isovector-vector coupling in quark matter. We employ the relativistic mean-field theory with an extended TM1 parameter set to describe hadronic matter and the SU(3) Nambu-Jona-Lasinio model with isovector-vector and hypercharge-vector couplings to describe the quark matter. The deconfinement hadron-quark phase transition is constructed under Gibbs phase equilibrium conditions. It is found that the isovector-vector and hypercharge-vector couplings in quark matter enhance the symmetry energy and hypercharge symmetry energy in neutron-star matter.

    nucl-thAIP Conf.Proc.(2019)·8 citations
  6. 06

    Probing chiral interactions up to next-to-next-to-next-to-leading order in medium-mass nuclei

    J. Hoppe · C. Drischler · K. Hebeler · A. Schwenk · J. Simonis

    We study ground-state energies and charge radii of closed-shell medium-mass nuclei based on novel chiral nucleon-nucleon (NN) and three-nucleon (3N) interactions, with a focus on exploring the connections between finite nuclei and nuclear matter. To this end, we perform in-medium similarity renormalization group (IM-SRG) calculations based on chiral interactions at next-to-leading order (NLO), NLO, and NLO, where the 3N interactions at NLO and NLO are fit to the empirical saturation point of nuclear matter and to the triton binding energy. Our results for energies and radii at NLO and NLO overlap within uncertainties, and the cutoff variation of the interactions is within the EFT uncertainty band. We find underbound ground-state energies, as expected from the comparison to the empirical saturation point. The radii are systematically too large, but the agreement with experiment is better. We further explore variations of the 3N couplings to test their sensitivity in nuclei. While nuclear matter at saturation density is quite sensitive to the 3N couplings, we find a considerably weaker dependence in medium-mass nuclei. In addition, we explore a consistent momentum-space SRG evolution of these NN and 3N interactions, exhibiting improved many-body convergence. For the SRG-evolved interactions, the sensitivity to the 3N couplings is found to be stronger in medium-mass nuclei.

    nucl-thPRC(2019)·68 citations
  7. 07

    Extracting the strangeness freeze-out temperature from net-Kaon data at RHIC

    Rene Bellwied🇺🇸 · Jacquelyn Noronha-Hostler🇺🇸 · Paolo Parotto🇺🇸 · Israel Portillo Vazquez🇺🇸 · Claudia Ratti🇺🇸 · Jamie Stafford🇺🇸

    Using the moments of the net-kaon distribution calculated within a state of-the-art hadron resonance gas model compared to experimental data from STAR's Beam Energy Scan, we find that the extracted strange freeze-out temperature is incompatible with the light one extracted from net-proton and net-charge fluctuations. Additionally predictions for net- fluctuations are made that also appear to be consistent with a higher freeze-out temperature for strange particles. This strangeness freeze-out temperature is roughly MeV higher than the corresponding light freeze-out temperature. We also discuss cross-susceptibilities using different identified particles, which may be a further test of this two freeze-out temperature picture. Finally, we lay out the necessary updates needed in relativistic hydrodynamic models to take into account for this two freeze-out temperature scenario and present preliminary results of spectra at RHIC for AuAu GeV collisions that indicate a higher freeze-out temperature is preferred.

    nucl-thhep-phPoS(2019)·4 citations

Affiliations

first authorsco-authorsvia INSPIRE