Browsing by Author "Meibner, Ulf G."

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    Effective field theory for collective rotations and vibrations of triaxially deformed nuclei
    (American Physical Society, 2018) Chen, Q. B.; Kaiser, N.; Meibner, Ulf G.; Meng, Jie
    The effective field theory (EFT) for triaxially deformed even-even nuclei is generalized to include the vibrational degrees of freedom. The pertinent Hamiltonian is constructed up to next-to-leading order (NLO). The leading-order part describes the vibrational motion, and the NLO part couples rotations to vibrations. The applicability of the EFT Hamiltonian is examined through the description of the energy spectra of the ground state bands, γ bands, and K=4 bands in the 108,110,112Ru isotopes. It is found that, by taking into account the vibrational degrees of freedom, the deviations for high-spin states in the γ band observed in the EFT with only rotational degrees of freedom disappear. This supports the importance of including vibrational degrees of freedom in the EFT formulation for the collective motion of triaxially deformed nuclei.
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    Nuclear matter properties with nucleon-nucleon forces up to fifth order in the chiral expansion
    (American Physical Society, 2017) Hu, Jinniu; Zhang, Ying; Epelbaum, Evgeny; Meibner, Ulf G.
    The properties of nuclear matter are studied using state-of-the-art nucleon-nucleon forces up to fifth order in chiral effective field theory. The equations of state of symmetric nuclear matter and pure neutron matter are calculated in the framework of the Brueckner-Hartree-Fock theory. We discuss in detail the convergence pattern of the chiral expansion and the regulator dependence of the calculated equations of state and provide an estimation of the truncation uncertainty. For all employed values of the regulator, the fifth-order chiral two-nucleon potential is found to generate nuclear saturation properties similar to the available phenomenological high precision potentials. We also extract the symmetry energy of nuclear matter, which is shown to be quite robust with respect to the chiral order and the value of the regulator.