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Nuclear Theory·nucl-th

Thursday·June 30, 2016

8 papers—4 primary·4 cross-listed

All8Primary4Cross-lists4
  1. 01

    Tetrahedral shapes of neutron-rich Zr isotopes from multidimensionally-constrained relativistic Hartree-Bogoliubov model

    Jie Zhao · Bing-Nan Lu · En-Guang Zhao · Shan-Gui Zhou

    We develop a multidimensionally constrained relativistic Hartree-Bogoliubov (MDC-RHB) model in which the pairing correlations are taken into account by making the Bogoliubov transformation. In this model, the nuclear shape is assumed to be invariant under the reversion of and axes; i.e., the intrinsic symmetry group is and all shape degrees of freedom with even are included self-consistently. The RHB equation is solved in an axially deformed harmonic oscillator basis. A separable pairing force of finite range is adopted in the MDC-RHB model. The potential energy curves of neutron-rich even-even Zr isotopes are calculated with relativistic functionals DD-PC1 and PC-PK1 and possible tetrahedral shapes in the ground and isomeric states are investigated. The ground state shape of Zr is predicted to be tetrahedral with both functionals and so is that of Zr with the functional DD-PC1. The tetrahedral ground states are caused by large energy gaps around and when deformation is included. Although the inclusion of the deformation can also reduce the energy around and lead to minima with pear-like shapes for nuclei around Zr, these minima are unstable due to their shallowness.

    nucl-thnucl-exPRC(2017)·61 citations
  2. 02

    Closing the equations of motion of anisotropic fluid dynamics by a judicious choice of moment of the Boltzmann equation

    Etele Molnár🇩🇪 · Harri Niemi🇩🇪 · Dirk H. Rischke🇩🇪

    In Molnár et al. [Phys. Rev. D 93, 114025 (2016)] the equations of anisotropic dissipative fluid dynamics were obtained from the moments of the Boltzmann equation based on an expansion around an arbitrary anisotropic single-particle distribution function. In this paper we make a particular choice for this distribution function and consider the boost-invariant expansion of a fluid in one dimension. In order to close the conservation equations, we need to choose an additional moment of the Boltzmann equation. We discuss the influence of the choice of this moment on the time evolution of fluid-dynamical variables and identify the moment that provides the best match of anisotropic fluid dynamics to the solution of the Boltzmann equation in the relaxation-time approximation.

    nucl-thhep-phphysics.flu-dynphysics.plasm-phPRD(2016)·75 citations
  3. 03

    Triplet Pairing in pure neutron matter

    Sarath Srinivas (IIT M)🇮🇳 · S. Ramanan (IIT M)🇮🇳

    We study the zero temperature BCS gaps for the triplet channel in pure neutron matter using Similarity Renormalization Group (SRG) evolved interactions. We use the dependence of the results on the SRG resolution scale, as a tool to analyze medium and many-body corrections. In particular, we study the effects of including the three-body interactions at leading order, which appear at N2LO in the Chiral EFT, as well as that of the first-order self-energy corrections on the zero temperature gap. In addition we also extract the transition temperature as a function of densities and verify the BCS scaling of the zero temperature gaps to the transition temperature. We observe that the self-energy effects are very crucial in order to reduce the SRG resolution scale dependence of the results, while the three-body effects at the leading order do not change the two-body resolution scale dependence. On the other hand, the results depend strongly on the three-body cut-off, emphasizing the importance of the missing higher-order three-body effects. We also observe that self-energy effects reduce the overall gap as well as shift the gap closure to lower densities.

    nucl-thcond-mat.quant-gasPRC(2016)·31 citations
  4. 04

    Quantum Phase Transition in the Shape of Zr isotopes

    Tomoaki Togashi · Yusuke Tsunoda · Takaharu Otsuka · Noritaka Shimizu

    The rapid shape change in Zr isotopes near neutron number =60 is identified to be caused by type II shell evolution associated with massive proton excitations to its orbit, and is shown to be a quantum phase transition. Monte Carlo shell-model calculations are carried out for Zr isotopes of =50-70 with many configurations spanned by eight proton orbits and eight neutron orbits. Energy levels and B(E2) values are obtained within a single framework in a good agreement with experiments, depicting various shapes in going from =50 to 70. Novel coexistence of prolate and triaxial shapes is suggested.

    nucl-thnucl-exPRL(2016)·230 citations

Affiliations

first authorsco-authorsvia INSPIRE