The seesaw mechanism at TeV scale in the 3-3-1 model with right-handed neutrinos

We implement the seesaw mechanism in the 3-3-1 model with right-handed neutrinos. This is accomplished by the introduction of a scalar sextet into the model and the spontaneous violation of the lepton number. We identify the Majoron as a singlet under $SU_L(2)\otimes U_Y(1)$ symmetry, which makes it safe under the current bounds imposed by electroweak data. The main result of this work is that the seesaw mechanism works already at TeV scale with the outcome that the right-handed neutrino masses lie in the electroweak scale, in the range from MeV to tens of GeV. This window provides a great opportunity to test their appearance at current detectors, though when we contrast our results with some previous analysis concerning detection sensitivity at LHC, we conclude that further work is needed in order to validate this search.Comment: about 13 pages, no figure

x_F-dependence of J/Psi suppression in pA collisions

Coherence effects are important in the description of collisions with extended objects as nuclei. At fixed target energies and small x_F, the coherence length of the fluctuation containing the $c\bar c$ is small and the usual nuclear absorption model is valid. However, at higher energies and/or x_F the nucleus is seen as a whole by the fluctuation. In this case, the total, not the absorptive, $c\bar c-N$ cross section controls the suppression and also shadowing of gluons appears. We propose that the growth of the coherence length can explain the x_F-dependence of present experimental data. For this, we need a ratio of absorptive over total $c\bar c-N$ cross section of 0.2.Comment: 15 pages, 3 postscript figure

Moment Analysis, Multiplicity Distributions and Correlations in High Energy Processes: Nucleus-Nucleus Collisions

Cumulant oscillations, or $H_q$ moment oscillations, appear if the KNO multiparticle distribution decreases at large z, $z\equiv n/$, faster than the exponential, $exp(-D z^\mu)$, with $\mu > 1$. In nucleus-nucleus interactions this behaviour is related to the limitation in the average number of elementary central collisions (or average number of strings centrally produced), due to the finite number of nucleons involved. Colour deconfinement, via percolating string fusion, will drastically decrease the fraction of centrally produced strings and increase the cut-off parameter $\mu$: Moment oscillations will be displaced to smaller q and the width of the KNO distribution and forward-backward particle correlations will become smaller.Comment: 11 pages, 2 Postscript figure

The Milky Way Bulge: Observed properties and a comparison to external galaxies

The Milky Way bulge offers a unique opportunity to investigate in detail the role that different processes such as dynamical instabilities, hierarchical merging, and dissipational collapse may have played in the history of the Galaxy formation and evolution based on its resolved stellar population properties. Large observation programmes and surveys of the bulge are providing for the first time a look into the global view of the Milky Way bulge that can be compared with the bulges of other galaxies, and be used as a template for detailed comparison with models. The Milky Way has been shown to have a box/peanut (B/P) bulge and recent evidence seems to suggest the presence of an additional spheroidal component. In this review we summarise the global chemical abundances, kinematics and structural properties that allow us to disentangle these multiple components and provide constraints to understand their origin. The investigation of both detailed and global properties of the bulge now provide us with the opportunity to characterise the bulge as observed in models, and to place the mixed component bulge scenario in the general context of external galaxies. When writing this review, we considered the perspectives of researchers working with the Milky Way and researchers working with external galaxies. It is an attempt to approach both communities for a fruitful exchange of ideas.Comment: Review article to appear in "Galactic Bulges", Editors: Laurikainen E., Peletier R., Gadotti D., Springer Publishing. 36 pages, 10 figure

Sensor Surface Design with NanoMaterials: A New Platform in the Diagnosis of COVID-19

Mass testing for COVID-19 is essential to defining patient management strategies, choosing the best clinical management, and dimensioning strategies for controlling viral dissemination and immunization strategies. Thus, it is of utmost importance to search for devices that allow a quick and reliable diagnosis of low cost that can be transposed from the bench to the bedside, such as biosensors. These devices can help choose the correct clinical management to minimize factors that lead to infected patients developing more severe diseases. The use of nanomaterials to modify biosensors’ surfaces to increase these devices’ sensitivity and their biofunctionality enables high-quality nanotechnological platforms. In addition to the diagnostic benefits, nanotechnological platforms that facilitate the monitoring of anti-SARS-CoV-2 antibodies may be the key to determining loss of protective immune response after an episode of COVID-19, which leads to a possible chance of reinfection, as well as how they can be used to assess and monitor the success of immunization strategies, which are beginning to be administered on a large scale and that the extent and duration of their protection will need to be determined. Therefore, in this chapter, we will cover nanomaterials’ use and their functionalities in the surface design of sensors, thus generating nanotechnological platforms in the various facets of the diagnosis of COVID-19