Dark Matter scenarios at IceCube

The recent study on the the 6-year up-going muon neutrinos by the IceCube Collaboration and the multi-messenger analyses support the hypothesis of a two-component scenario explaining the diffuse TeV-PeV neutrino flux. Depending on the steepness of the astrophysical power-law, an excess in the IceCube data is shown in the energy range 10-100 TeV (low-energy excess) or at PeV (high-energy excess). In both cases, we characterize a two-component neutrino flux where decaying Dark Matter particles provide a contribution to the IceCube observations.Comment: 5 pages, 2 figures. Prepared for the proceedings of the conference NOW 201

The IceCube low-energy excess: a Dark Matter interpretation

The recent study on the the 6-year up-going muon neutrinos by the IceCube Collaboration support the hypothesis of a two-component scenario explaining the diffuse TeV-PeV neutrino flux. Once a hard astrophysical power-law is considered, an excess in the IceCube data is shown in the energy range 10-100 TeV (low-energy excess}). By means of a statistical analysis on the neutrino energy spectrum and on the angular distribution of neutrino arrival directions, we characterize a two-component neutrino flux where decaying/annihilating Dark Matter particles provide a contribution to the IceCube observations.Comment: 4 pages, 1 figure. Prepared for the proceedings of the conference IFAE 201

IceCube PeV Neutrinos and Leptophilic Dark Matter

We analyze the scenario where the IceCube high energy neutrino events are explained in terms of an extraterrestrial flux due to two different components: a contribution coming from know astrophysical sources for energies up to few hundreds TeV and a top-down contribution originated by the decay of heavy dark matter particles with a mass of few PeV. Contrary to previous approaches, we consider a leptophilic three-body decay that dominates at PeV energies due to the absence of quarks in the final state. We find that the theoretical predictions of such a scenario are in a slightly better agreement with the IceCube data if the astrophysical component has a cut-off at about 100 TeV. This interpretation of IceCube data can be easily tested in the near future since the decaying dark matter scenario predicts a sharp cut-off at PeV energy scale and the observation of an anisotropy towards Galactic Center of our Galaxy in contrast with the isotropic astrophysical flux.Comment: 5 pages, 1 figure. Prepared for the proceedings of the conference TAUP 201

Interpreting IceCube 6-year HESE data as an evidence for hundred TeV decaying Dark Matter

The assumption of a single astrophysical power-law flux to explain the IceCube 6-year HESE extraterrestrial events yields a large spectral index that is in tension with gamma-ray observations and the 6-year up-going muon neutrinos data. Adopting a spectral index belonging to the range $\left[2.0,2.2\right]$, which is compatible with the one deduced by the analysis performed on the 6-year up-going muon neutrinos data and with $p$-$p$ astrophysical sources, the latest IceCube data show an up to $2.6\,\sigma$ excess in the number of events in the energy range 40--200 TeV. We interpret such an excess as a decaying Dark Matter signal and we perform a likelihood-ratio statistical test to compare the two-component scenario with respect to the single-component one.Comment: 7 pages, 4 figures. v2: version published in PL

Chances for SUSY-GUT in the LHC Epoch

The magic couple of SUSY and GUT still appears the most elegant and predictive physics concept beyond the Standard Model. Since up to now LHC found no evidence for supersymmetric particles it becomes of particular relevance to determine an upper bound of the energy scale they have to show up. In particular, we have analyzed a generic SUSY-GUT model assuming one step unification like in SU(5), and adopting naturalness principles, we have obtained general bounds on the mass spectrum of SUSY particles. We claim that if a SUSY gauge coupling unification takes place, the lightest gluino or Higgsino cannot have a mass larger than about 20 TeV. Such a limit is of interest for planning new accelerator machines.Comment: 23 pages, 5 figures. Version published in JHEP, minor corrections added and images improve

A novel approach for the production of nitrogen doped TiO2 nanoparticles

In this study a visible light active nitrogen doped nanostructure titanium dioxide was synthesized by a simple mixing of Degussa P25 and Urea powder and further thermal treatment under the adequate conditions. Photocatalytic activity of produced nanoparticles was verified by providing of photocatalytic degradation of phenol aqueous solution. Mainly this work was focused on the investigation of the following effects: urea concentration, temperature treatment, catalyst loading and initial phenol concentration. Kinetics study was also carried out. The approach appears to be successful and may be applied for example during the photocatalytic treatment of wastewater streams without or with a limited aid of UV lamps. Copyright © 2015, AIDIC Servizi S.r.l

CFD model of a spinning disk reactor for nanoparticle production

The use of a spinning disk reactor (SDR) was investigated for the continuous production of nanoparticles of hydroxyapatite. SDR is an effective apparatus for the production of nanoparticles by wet chemical synthesis. Rotation of the disc surface at high speed creates high centrifugal fields, which promote thin film flow with a thickness in the range 50-500 ?m. Films are highly sheared and have numerous unstable surface ripples, giving rise to intense mixing. SDR performances are strongly affected by the adopted operating conditions such as the influence of rotation speed that determines the attainment of micro-mixing and the feeding point location that has a great influence on the particle size distribution of the product. The experimental device consists of a cylindrical vessel with an inner disk, 8.5 cm in diameter, made by PVC coated by an acrylic layer. The rotational velocity of the disc is controlled and ranges from 0 to 147 rad/s. The reagent solutions are fed over the disk at a distance of 5 mm from the disc surface through tubes, 1 mm in diameter. A computational fluid dynamic model, validated in a previous work, was used to optimize the operative conditions of SDR. Through the CFD model it is possible to analyse the hydrodynamic of the thin liquid film formed on the disk at different speed rotations and to individuate the best mixing conditions between the reagents varying the feeding point positions. The production of hydroxyapatite was also investigated adding the reaction kinetic to model the product formation in the liquid phase and the population balance equation to predict particle size distribution. The simulation results were compared with available experimental data showing that the CFD model is fully capable to describe the process and qualifies as a suitable engineering tool to perform the SDR process design. Copyright © 2015, AIDIC Servizi S.r.l

Developing and Assessing Teaching Effectiveness

AbstractWho is an effective teacher? It isn’t possible to give a single answer to this question because defining a teacher isn’t a simple question. Many studies have demonstrated that an effective teacher can have an enriching effect on the daily lives of children and their lifelong educational and career aspirations and can also have a direct influence in enhancing student learning. That's why it isn’t possible to define an effective teacher only referring to their students’ grades; the question is much more complex; as a matter of fact we can say that it has a multi-dimension character. Starting from this point of view it's important to define the suitable methods/instruments of a teacher's evaluation and capability