Bounce in Valley: Study of the extended structures from thick-wall to thin-wall vacuum bubbles

The valley structure associated with quantum meta-stability is examined. It is defined by the new valley equation, which enables consistent evaluation of the imaginary-time path-integral. We study the structure of this new valley equation and solve these equations numerically. The valley is shown to contain the bounce solution, as well as other bubble structures. We find that even when the bubble solution has thick wall, the outer region of the valley is made of large-radius, thin-wall bubble, which interior is occupied by the true-vacuum. Smaller size bubbles, which contribute to decay at higher energies, are also identified.Comment: 9 pages + 4 figures, KUCP-006

Matter distribution and spin-orbit force in spherical nuclei

We investigate the possibility that some nuclei show density distributions with a depletion in the center, a semi-bubble structure, by using a Hartree-Fock plus Bardeen-Cooper-Schrieffer approach. We separately study the proton, neutron and matter distributions in 37 spherical nuclei mainly in the $s - d$ shell region. We found a relation between the semi-bubble structure and the energy splitting of spin-orbit partner single particle levels. The presence of semi-bubble structure reduces this splitting, and we study its consequences on the excitation spectrum of the nuclei under investigation by using a quasi-particle random-phase-approximation approach. The excitation energies of the low-lying $4^+$ states can be related to the presence of semi-bubble structure in nuclei.Comment: 15 pages, 7 tables, 11 figures. Version accepted for publication in Phys. Rev. C; the number of nuclei analysed has been reduced; some figure have bee redrawn, and a new figure and some references have been adde

Reconstruction of the bubble nucleating potential

We calculate analytically the bubble nucleation rate in a model of first order inflation which is able to produce large scale structure. The computation includes the first-order departure from the thin-wall limit, the explicit derivation of the pre-exponential factor, and the gravitational correction. The resulting bubble spectrum is then compared with constraints from the large scale structure and the microwave background. We show that there are models which pass all the constraints and produce bubble-like perturbations of interesting size. Furthermore, we show that it is in principle possible to reconstruct completely the inflationary two-field potential from observations.Comment: Accepted for publication in Phys. Rev. D, 19 pages, 2 ps figs include

Does a proton "bubble" structure exist in the low-lying states of 34Si?

The possible existence of a "bubble" structure in the proton density of $^{34}$Si has recently attracted a lot of research interest. To examine the existence of the "bubble" structure in low-lying states, we establish a relativistic version of configuration mixing of both particle number and angular momentum projected quadrupole deformed mean-field states and apply this state-of-the-art beyond relativistic mean-field method to study the density distribution of the low-lying states in $^{34}$Si. An excellent agreement with the data of low-spin spectrum and electric multipole transition strengths is achieved without introducing any parameters. We find that the central depression in the proton density is quenched by dynamic quadrupole shape fluctuation, but not as significantly as what has been found in a beyond non-relativistic mean-field study. Our results suggest that the existence of proton "bubble" structure in the low-lying excited $0^+_2$ and $2^+_1$ states is very unlikely.Comment: 6 pages, 8 figures and 1 table, accepted for publication in Physics Letters

Semi-flexible Additive Manufacturing Materials for Modularization Purposes - A modular assembly proposal for a foam edge-based spatial framework

This paper introduces a series of design and fabrication tests directed towards the use of bendable 3D printing materials in order to simplify a foam bubble-based geometry as a frame structure for modular assembly. The aspiration to reference a spittlebug's bubble cocoon in nature for a light installation in the urban context was integrated into a computational workflow conditioning light-weight, material-, and cost savings along with assembly-simplicity. Firstly, before elaborating on the project motivation and background in foam structures and applications of 3D-printed thermoplastic polyurethane (TPU) material, this paper describes the physical nature of bubble foams in its relevant aspects. Subsequently this is implemented into the parametric design process for an optimized foam structure with Grasshopper clarifying the need for flexible materials to enhance modular feasibility. Following, the additive manufacturing iterations of the digitally designed node components with TPU are presented and evaluated. Finally, after the test assembly of both components is depicted, this paper assesses the divergence between natural foams and the case study structure with respect to self-organizing behavior