Standard Model False Vacuum Inflation: Correlating the Tensor-to-Scalar Ratio to the Top Quark and Higgs Boson masses

For a narrow band of values of the top quark and Higgs boson masses, the Standard Model Higgs potential develops a false minimum at energies of about $10^{16}$ GeV, where primordial Inflation could have started in a cold metastable state. A graceful exit to a radiation-dominated era is provided, e.g., by scalar-tensor gravity models. We pointed out that if Inflation happened in this false minimum, the Higgs boson mass has to be in the range $126.0 \pm 3.5$ GeV, where ATLAS and CMS subsequently reported excesses of events. Here we show that for these values of the Higgs boson mass, the inflationary gravitational wave background has be discovered with a tensor-to-scalar ratio at hand of future experiments. We suggest that combining cosmological observations with measurements of the top quark and Higgs boson masses represents a further test of the hypothesis that the Standard Model false minimum was the source of Inflation in the Universe.Comment: v1: 4 pages, 2 figures; v2: 5 pages, 2 figures, improvements in the text; v3: 5 pages, 2 figures, minor improvements in the text, matches PRL versio

Empowering formative assessment using embedded Web Widgets in Wikis

The article can be viewed at: http://opensym.org/wsos2013/proceedings/p0901-notari.pdfIn this article we describe how we developed and how we use a tool for teachers enhancing inter-group collaboration of learners using wikis in project-based learning settings with over 100 participants, where different groups of students develop similar projects and each project has an own wiki page. To achieve our goal we extended typical wiki functionality by using web widgets, mini applications embedded anywhere in the wiki environment using the iframe tag. Two different evaluation widgets (rating widget and 'working progress' widget) are placed on each of the project pages. The project groups use the 'working progress' widget to declare the amount of work done. The teacher and the rest of the learning community use the 'rating' widget to rate the ongoing project work. A so called 'meta widget' showing a summary of the results of the 'rating' and 'working progress' widget can be displayed on the start page of the learning community or if a project is divided in different milestones, on the page describing the goals and timeline for the milestone. Evaluation widgets and meta widget, which easily can be embedded by the teacher potentially all over the wiki pages, enhances visibility of quality and termination degree of a project and enhance so the self, the tutor and the peer review opportunities in such large scale project based learning settings. The created evaluation widgets and meta widgets have been embedded in the wiki of a three months curriculum. The evaluation of utility and usability of the widgets is ongoing. The educational value of rating and reflecting about the working progress of a given task is discussed

Development of a glass-ceramic glaze formulated from industrial residues to improve the mechanical properties of the porcelain stoneware tiles

In this research a mixture of 90%wt of industrial residues (recycled soda-lime glass and ashes from a coalpower thermal plant) have been vitrified for their use as ‘‘secondary raw material”. Then, a glaze suspen-sion was prepared to be applied on the porcelain stoneware tile. The tested pieces have been fired by aconventional porcelain cycle at 1180 °C of maximum temperature. The XRD, XRF, SEM/EDS and thedilatometric analysis have been the instrumental techniques used to characterize the material. Finally,an ecological glass-ceramic glaze perfectly fitting on porcelain ceramic tile has been produced, exhibitinga unique phase, anorthite, which ensures a high flexural strength (around 96 MPa) and a significantVickers microhardness of 250 GPa, improving the mechanical properties of a conventional the porcelainceramic tile

"Swiss-Cheese" Inhomogeneous Cosmology & the Dark Energy Problem

We study an exact swiss-cheese model of the Universe, where inhomogeneous LTB patches are embedded in a flat FLRW background, in order to see how observations of distant sources are affected. We find negligible integrated effect, suppressed by (L/R_{H})^3 (where L is the size of one patch, and R_{H} is the Hubble radius), both perturbatively and non-perturbatively. We disentangle this effect from the Doppler term (which is much larger and has been used recently \cite{BMN} to try to fit the SN curve without dark energy) by making contact with cosmological perturbation theory.Comment: 35 pages, 6 figure

Detecting the Cold Spot as a Void with the Non-Diagonal Two-Point Function

The anomaly in the Cosmic Microwave Background known as the "Cold Spot" could be due to the existence of an anomalously large spherical (few hundreds Mpc/h radius) underdense region, called a "Void" for short. Such a structure would have an impact on the CMB also at high multipoles l through Lensing. This would then represent a unique signature of a Void. Modeling such an underdensity with an LTB metric, we show that the Lensing effect leads to a large signal in the non-diagonal two-point function, centered in the direction of the Cold Spot, such that the Planck satellite will be able to confirm or rule out the Void explanation for the Cold Spot, for any Void radius with a Signal-to-Noise ratio of at least O(10).Comment: v1: 6 pages, 2 figures; v2: 6 pages, 2 figures, text improved, to appear on JCA

Gradient expansion(s) and dark energy

Motivated by recent claims stating that the acceleration of the present Universe is due to fluctuations with wavelength larger than the Hubble radius, we present a general analysis of various perturbative solutions of fully inhomogeneous Einstein equations supplemented by a perfect fluid. The equivalence of formally different gradient expansions is demonstrated. If the barotropic index vanishes, the deceleration parameter is always positive semi-definite.Comment: 17 pages, no figure

Cosmological Backreaction from Perturbations

We reformulate the averaged Einstein equations in a form suitable for use with Newtonian gauge linear perturbation theory and track the size of the modifications to standard Robertson-Walker evolution on the largest scales as a function of redshift for both Einstein de-Sitter and Lambda CDM cosmologies. In both cases the effective energy density arising from linear perturbations is of the order of 10^-5 the matter density, as would be expected, with an effective equation of state w ~ -1/19. Employing a modified Halofit code to extend our results to quasilinear scales, we find that, while larger, the deviations from Robertson-Walker behaviour remain of the order of 10^-5.Comment: 15 pages, 8 figures; replaced by version accepted by JCA

Local Void vs Dark Energy: Confrontation with WMAP and Type Ia Supernovae

It is now a known fact that if we happen to be living in the middle of a large underdense region, then we will observe an "apparent acceleration", even when any form of dark energy is absent. In this paper, we present a "Minimal Void" scenario, i.e. a "void" with minimal underdensity contrast (of about -0.4) and radius (~ 200-250 Mpc/h) that can, not only explain the supernovae data, but also be consistent with the 3-yr WMAP data. We also discuss consistency of our model with various other measurements such as Big Bang Nucleosynthesis, Baryon Acoustic Oscillations and local measurements of the Hubble parameter, and also point out possible observable signatures.Comment: Minor numerical errors and typos corrected, references adde

Cosmic Acceleration Driven by Mirage Inhomogeneities

A cosmological model based on an inhomogeneous D3-brane moving in an AdS_5 X S_5 bulk is introduced. Although there is no special points in the bulk, the brane Universe has a center and is isotropic around it. The model has an accelerating expansion and its effective cosmological constant is inversely proportional to the distance from the center, giving a possible geometrical origin for the smallness of a present-day cosmological constant. Besides, if our model is considered as an alternative of early time acceleration, it is shown that the early stage accelerating phase ends in a dust dominated FRW homogeneous Universe. Mirage-driven acceleration thus provides a dark matter component for the brane Universe final state. We finally show that the model fulfills the current constraints on inhomogeneities.Comment: 14 pages, 1 figure, IOP style. v2, changed style, minor corrections, references added, version accepted in Class. Quant. Gra