Structural evolution in germanium and selenium nuclei within the mapped interacting boson model based on the Gogny energy density functional

The shape transitions and shape coexistence in the Ge and Se isotopes are studied within the interacting boson model (IBM) with the microscopic input from the self-consistent mean-field calculation based on the Gogny-D1M energy density functional. The mean-field energy surface as a function of the quadrupole shape variables $\beta$ and $\gamma$, obtained from the constrained Hartree-Fock-Bogoliubov method, is mapped onto the expectation value of the IBM Hamiltonian with configuration mixing in the boson condensate state. The resultant Hamiltonian is used to compute excitation energies and electromagnetic properties of the selected nuclei $^{66-94}$Ge and $^{68-96}$Se. Our calculation suggests that many nuclei exhibit $\gamma$ softness. Coexistence between prolate and oblate, as well as between spherical and $\gamma$-soft, shapes is also observed. The method provides a reasonable description of the observed systematics of the excitation energy of the low-lying energy levels and transition strengths for nuclei below the neutron shell closure $N=50$, and provides predictions on the spectroscopy of neutron-rich Ge and Se isotopes with $52\leq N\leq 62$, where data are scarce or not available.Comment: 16 pages, 20 figure

Spectroscopy of quadrupole and octupole states in rare-earth nuclei from a Gogny force

Collective quadrupole and octupole states are described in a series of Sm and Gd isotopes within the framework of the interacting boson model (IBM), whose Hamiltonian parameters are deduced from mean field calculations with the Gogny energy density functional. The link between both frameworks is the ($\beta_2\beta_3$) potential energy surface computed within the Hartree-Fock-Bogoliubov framework in the case of the Gogny force. The diagonalization of the IBM Hamiltonian provides excitation energies and transition strengths of an assorted set of states including both positive and negative parity states. The resultant spectroscopic properties are compared with the available experimental data and also with the results of the configuration mixing calculations with the Gogny force within the generator coordinate method (GCM). The structure of excited $0^{+}$ states and its connection with double octupole phonons is also addressed. The model is shown to describe the empirical trend of the low-energy quadrupole and octupole collective structure fairly well, and turns out to be consistent with GCM results obtained with the Gogny force.Comment: 17 pages, 12 figures, 4 table

Effective 4D propagation of a charged scalar particle in Visser brane world

In this work we extend an analysis due to Visser of the effective propagation of a neutral scalar particle on a brane world scenario which is a particular solution of the five dimensional Einstein-Maxwell equations with cosmological constant having an electric field pointing in the extra spatial dimension. We determine the dispersion relations of a charged scalar particle to first order in a perturbative analysis around those of the neutral particle. Since depending on whether the particle is charged or not the dispersion relations change, we could collect bulk information, namely the presence of the electric field, by studying the 4D dynamics of the particles.Comment: 12 pages, 5 figure

Scalar Field Dark Matter: behavior around black holes

We present the numerical evolution of a massive test scalar fields around a Schwarzschild space-time. We proceed by using hyperboloidal slices that approach future null infinity, which is the boundary of scalar fields, and also demand the slices to penetrate the event horizon of the black hole. This approach allows the scalar field to be accreted by the black hole and to escape toward future null infinity. We track the evolution of the energy density of the scalar field, which determines the rate at which the scalar field is being diluted. We find polynomial decay of the energy density of the scalar field, and use it to estimate the rate of dilution of the field in time. Our findings imply that the energy density of the scalar field decreases even five orders of magnitude in time scales smaller than a year. This implies that if a supermassive black hole is the Schwarzschild solution, then scalar field dark matter would be diluted extremely fastComment: 15 pages, 21 eps figures. Appendix added, accepted for publication in JCA

Scalar Field Dark Matter: non-spherical collapse and late time behavior

We show the evolution of non-spherically symmetric balls of a self-gravitating scalar field in the Newtonian regime or equivalently an ideal self-gravitating condensed Bose gas. In order to do so, we use a finite differencing approximation of the Shcr\"odinger-Poisson (SP) system of equations with axial symmetry in cylindrical coordinates. Our results indicate: 1) that spherically symmetric ground state equilibrium configurations are stable against non-spherical perturbations and 2) that such configurations of the SP system are late-time attractors for non-spherically symmetric initial profiles of the scalar field, which is a generalization of such behavior for spherically symmetric initial profiles. Our system and the boundary conditions used, work as a model of scalar field dark matter collapse after the turnaround point. In such case, we have found that the scalar field overdensities tolerate non-spherical contributions to the profile of the initial fluctuation.Comment: 8 revtex pages, 10 eps figures. Accepted for publication in PR