Aspects of Leptogenesis Scenarios at Grand Unification and Sub-TeV Scales and Their Possible Low-Energy Tests

In the present Thesis, we investigate various aspects of leptogenesis scenarios based on the type-I seesaw extension of the Standard Model (SM) with 2, 3 heavy Majorana neutrinos $N_j$ with masses $M_j$, $j = 1,\,...,\,3$, as well as the possibilities to test the scenarios considered by us in currently running and/or future planned low-energy experiments. We focus first on the high-scale leptogenesis framework with strongly hierarchical mass spectrum of the heavy Majorana neutrinos, namely $M_1$ << $M_2$ << $M_3$, with $M_1$ in the range $(10^{8}-10^{14})$ GeV, concentrating on the possibility that the requisite CP-violation for the generation of the baryon asymmetry of the Universe $\eta_B$ is provided solely by the low-energy Dirac and/or Majorana phases of the light neutrino mixing (PMNS) matrix. A detailed numerical analysis of the solution to the quantum density matrix equations in this scenario, performed with the powerful ULYSSES code we have developed, reveals a number of novel features: i) $\eta_B$ going through zero and changing sign at the transitions between different flavour regimes (1-to-2 and 2-to-3) in the case of vanishing initial abundance of $N_1$ and strong wash-out effects; ii) inadequate description of the transitions between different flavour regimes by the corresponding Boltzmann equations; iii) flavour effects persisting beyond $10^{12}$ GeV and making it possible to reproduce the observed value of $\eta_B$ at these high-scales even though the CP-violation is provided only by the Dirac and/or Majorana phases of the PMNS matrix. Considering the somewhat simpler case of just two heavy Majorana neutrinos $N_{1,\,2}$ (with the heaviest $N_3$ decoupled) we show that relatively large part of the viable leptogenesis parameter space can be probed in low-energy neutrino experiments. We find, in particular, that, when the CP-violation is provided exclusively by the Dirac phase $\delta$ of the PMNS matrix, there is a correlation between the sign of $\sin\delta$ and the sign of $\eta_B$. This opens up the possibility to test part of the parameter space of this scenario in low-energy experiments on CP-violation in neutrino oscillations. A measurement of the Dirac and/or Majorana phases would also constrain the range of scales for which one can have viable leptogenesis in the considered scenario. Next, we show that in the low-scale resonant leptogenesis scenario with two heavy Majorana neutrinos $N_{1,\,2}$ forming a pseudo-Dirac pair, with $M\simeq M_{1,\,2}$ and a small mass splitting $| M_2-M_1 |$ << $M$, the observed $\eta_B$ can be reproduced for $M$ in the range $(0.1\sim 100)$ GeV by relying only on the decay mechanism, either during the production ("freeze-in") or departure from equilibrium ("freeze-out") of $N_{1,\,2}$. In this context, the inclusion of flavour and thermal effects in the formalism of Boltzmann equations is crucial for predicting the observed value of $\eta_B$. Also, we find that the viable parameter space of this resonant scenario is compatible with values of the heavy Majorana neutrino couplings to the SM that could be probed at future colliders, like at the discussed FCC-ee facility. When low-scale leptogenesis with three quasi-degenerate in mass heavy Majorana neutrinos $N_{1,\,2,\,3}$ with $M\simeq M_{1,\,2,\,3}$ is considered in the formalism of density matrix equations and, in particular, with both the heavy Majorana neutrino oscillation and decay mechanisms taken into account, the viable parameter space for $M$ in the range $(0.05-7\times 10^4)$ GeV enlarges considerably and becomes accessible to direct searches at the LHC, as well as in fixed target experiments and future colliders. We demonstrate that planned and upcoming experiments on charged lepton flavour violating processes with muons $\mu^\pm$, specifically MEG II on $\mu\to e\gamma$ decay, Mu3e on $\mu \to eee$ decay, Mu2e and COMET on $\mu - e$ conversion in aluminium and PRISM/PRIME on $\mu - e$ conversion in titanium, can test significant region of the viable leptogenesis parameter space and may potentially establish the first hint of such low-scale leptogenesis scenario

Direct Detection Constraints on Blazar-Boosted Dark Matter

We explore the possibility that relativistic protons in the extremely powerful jets of blazars may boost via elastic collisions the dark matter particles in the surroundings of the source to high energies. We concentrate on two sample blazars, TXS 0506 + 056, towards which IceCube recently reported evidence for a highenergy neutrino flux, and BL Lacertae, a representative nearby blazar. We find that the dark matter flux at Earth induced by these sources may be sizable, larger than the flux associated with the analogous process of dark matter boosted by galactic cosmic rays, and relevant to access direct detection for dark matter particle masses lighter than 1 GeV. From the null detection of a signal by XENON1T, MiniBooNE, and Borexino, we derive limits on dark matter-nucleus spin-independent and spin-dependent cross sections which, depending on the modelization of the source, improve on other currently available bounds for light dark matter candidates of 1 up to 5 orders of magnitude

Low-Scale Leptogenesis with Low-Energy Dirac CP-Violation

We study the freeze-in scenario of leptogenesis via oscillations within the type-I seesaw model with two quasi-degenerate heavy Majorana neutrinos $N_{1,\,2}$ having masses $M_2 > M_1 \sim (0.1-100)\,\text{GeV}$, $(M_2-M_1)/M_1 \ll 1$, focusing on the role of the CP-violation provided by the Dirac phase $\delta$ of the Pontecorvo-Maki-Nakagawa-Sakata lepton mixing matrix. We find that viable leptogenesis can be due solely to CP-violating values of $\delta$ and that the $N_{1,\,2}$ total mixing squared $\Theta^2=\sum_\alpha\Theta^2_\alpha$ needed is within the reach of future experiments, $\Theta_\alpha$ parameterising the coupling to the charged lepton $\alpha=e,\,\mu,\,\tau$. Furthermore, the required parameter space differs from that associated with additional Casas-Ibarra sources of CP-violation. Future determination of $\delta$, $\Theta^2$ and/or the ratios $\Theta_\tau^2:\Theta^2_\mu:\Theta^2_e$ would provide a critical test of the considered scenario.Comment: 7 pages, 2 figure

ULYSSES: Universal LeptogeneSiS Equation Solver

ULYSSES is a python package that calculates the baryon asymmetry produced from leptogenesis in the context of a type-I seesaw mechanism. The code solves the semi-classical Boltzmann equations for points in the model parameter space as specified by the user. We provide a selection of predefined Boltzmann equations as well as a plugin mechanism for externally provided models of leptogenesis. Furthermore, the ULYSSES code provides tools for multi-dimensional parameter space exploration. The emphasis of the code is on user flexibility and rapid evaluation. It is publicly available at https://github.com/earlyuniverse/ulyssesComment: 20 pages, 2 figures, 4 table

Thermal Leptogenesis in the Minimal Gauged U(1)Lμ−LτU(1)_{L_\mu-L_\tau} Model

We discuss the thermal leptogenesis mechanism within the minimal gauged U(1)$_{L_\mu-L_\tau}$ model to explain the observed baryon asymmetry of the Universe (BAU). In such framework, the phases of the Pontecorvo-Maki-Nakagawa-Sakata neutrino mixing matrix and the sum of the Standard Model neutrino masses are predictable because of a restricted neutrino mass matrix structure. Additionally, in the context of thermal leptogenesis, the BAU can be computed in terms of the three remaining free variables that parameterise the right-handed neutrino masses and their Yukawa couplings to the Higgs and lepton doublets. We identify the ranges of such parameters for which the correct BAU can be reproduced. We adopt the formalism of the density matrix equations to fully account for flavour effects and consider the decays of all the three right-handed neutrinos. Our analysis reveals that thermal leptogenesis is feasible within a wide parameter space, specifically for Yukawa couplings ranging from approximate unity to $\mathcal{O}(0.03-0.05)$ and mass of the lightest right-handed neutrino $M_1\gtrsim 10^{11-12}\,\text{GeV}$, setting a leptogenesis scale in the considered model which is higher than that of the non-thermal scenario.Comment: 22 pages, 4 figure

Blazar-boosted dark matter at Super-Kamiokande

Dark matter particles near the center of a blazar, after being accelerated by the elastic collisions with relativistic electrons and protons in the blazar jet, can be energetic enough to trigger detectable signals at terrestrial detectors. In this work, focusing on the blazars TXS 0506+056 and BL Lacertae, we derive novel limits on the cross section of the elastic scattering between dark matter and electrons by means of the available Super-Kamiokande data. Thanks to the large blazar-boosted dark matter flux, the limit on the dark matter-electron scattering cross section for dark matter masses below 100 MeV can be as low as similar to 10(-38) cm(2), that is orders of magnitude stronger than the analogous results from galactic cosmic rays

Le fideiussioni omnibus conformi allo schema ABI fra efficienza della tutela e protezione del mercato

Il saggio analizza il rapporto fra efficienza della tutela e salvaguardia del mercato avendo riguardo alla materia specifica in esame, quella dei contratti di fideiussione omnibus recanti clausole conformi ai modelli predisposti dall’Associazione bancaria italiana. In questi contratti il controllo sul contenuto del contratto dovrebbe avere come punto di riferimento l’esercizio dell’attività economica e, quindi, nella valutazione del meccanismo di tutela astrattamente applicabile non si dovrebbe trascurare la considerazione dei diversi interessi superindividuali tutelati dalla disciplina della concorrenza e del mercato

SUMO 2016 – Traffic, Mobility, and Logistics

Dear reader, You are holding in your hands a volume of the series „Reports of the DLR-Institute of Transportation Systems“. We are publishing in this series fascinating, scientific topics from the Institute of Trans- portation Systems of the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt e.V. – DLR) and from his environment. We are providing libraries with a part of the circulation. Outstanding scientific contributions and dissertations are here published as well as projects reports and proceedings of conferences in our house with different contributors from science, economy and politics. With this series we are pursuing the objective to enable a broad access to scientific works and results. We are using the series as well as to promote practically young researchers by the publication of the dissertation of our staff and external doctoral candidates, too. Publications are important milestones on the academic career path. With the series „Reports of the DLR-Institute of Transportation Systems / Berichte aus dem DLR-Institut für Verkehrssystemtechnik“ we are widening the spectrum of possible publications with a building block. Beyond that we understand the communication of our scientific fields of research as a contribution to the national and international research landscape in the fields of automotive, railway systems and traffic management. With this volume we publish the proceedings of the SUMO Conference 2016 which was held from 23rd to 25th May 2016 with a focus on traffic, mobility, and logistics. SUMO is an open source tool for traffic simulation that provides a wide range of traffic planning and simulation functionalities.The conference proceedings offer an overview of the applicability of the SUMO tool suite as well as its universal extensibility due to the availability of the source code. The major topic of this fourth edition of the SUMO conference are the different facets of moving objects occurring as personal mobility and freight delivery as well as communicating networks of intelligent vehicles. Several articles cover heterogeneous traffic networks, junction control and new traffic model extensions to the simulation. Subsequent specialized issues such as disaster management aspects and applying agile development techniques to scenario building are targeted as well. At the conference the international user community exchanged their experiences in using SUMO. With this volume we provide an insight to these experiences as inspiration for further projects with the SUMO suite