From The Universe to The Elementary Particles

Modern cosmology is a quickly developing ?eld of research. New technical devices and tools supply the community with new experimental data measured with high accuracy. The self-consistent explanation of these data needs t- oretical models that are based on hypothetical predictions of particle theory. In their turn, such predictions imply cosmology for their probe. Speci?c st- ies of the cosmological consequences of particle theory, linking them to their observable signatures, are actual. This boiling kettle of theoretical research and experimental efforts produces ideas that will be preserved for following generations.

It is the birth of neutrino astronomy. For the first time, astrophysicists can detect extra-terrestrial neutrinos in the ice of the South Pole. Neutrinos are the most common and also most mysterious elementary particles and as these particles are invisible to us, their mass is unknown.

This book is placed at the interface between string theory and elementary particle physics and shows novel results in the search for a heterotic string vacuum that reproduces those matter particles and interactions observed in our universe. The author provides a systematic classification of potentially realistic heterotic covariant lattice vacua, which possess a lower number of moduli fields when compared to conventional compactification methods, by means of number theoretical methods. These methods, while well known to the mathematics community, have not yet found many applications to physics.

This book sketches in detail, in its first part, some possible intriguing suggestions in order to conceive, and deal within a unified scheme, the dual aspects of particle and wave coexisting and conflicting in theoretical physics from the beginning of the 20th century, so opening a door to a deep harmonization of Relativity and Quantum Mechanics. And in the second part it presents a new approach to field unification, including gravity, together with the standard model of elementary particles and scalar boson, within the frame of multidimensional general relativistic universe. Cosmological application of the proposed theory involves non-trivial predictions about the still unexplained universe flatness, dark matter and dark energy. A way to gravity quantization appears also practicable.

Several of the very foundations of the cosmological standard model — the baryon asymmetry of the universe, dark matter, and the origin of the hot big bang itself — still call for an explanation from the perspective of fundamental physics. This work advocates one intriguing possibility for a consistent cosmology that fills in the theoretical gaps while being fully in accordance with the observational data. At very high energies, the universe might have been in a false vacuum state that preserved B-L, the difference between the baryon number B and the lepton number L as a local symmetry. In this state, the universe experienced a stage of hybrid inflation that only ended when the false vacuum became unstable and decayed, in the course of a waterfall transition, into a phase with spontaneously broken B-L symmetry. This B-L Phase Transition was accompanied by tachyonic preheating that transferred almost the entire energy of the false vacuum into a gas of B-L Higgs bosons, which in turn decayed into heavy Majorana neutrinos. Eventually, these neutrinos decayed into massless radiation, thereby producing the entropy of the hot big bang, generating the baryon asymmetry of the universe via the leptogenesis mechanism and setting the stage for the production of dark matter. Next to a variety of conceptual novelties and phenomenological predictions, the main achievement of the thesis is hence the fascinating notion that the leading role in the first act of our universe might have actually been played by neutrinos.

This book treats the subject of gravitational waves (GWs) production in binary stars or black-holes and in the early universe, using tools of quantum field theory which are familiar to graduate students and researchers in particle physics. A special focus is given to the generation of templates of gravitational wave signals from Feynman diagram calculations of transition amplitudes, which interests active researchers in GWs. The book presents field theory concepts, like supersymmetry realized in spinning binaries and soft-graviton theorems, that can have practical applications in novel GW signals, like the memory effect. The book also aims at specialists in both GWs and particle physics addressing cosmological models of phase transition and inflation that can be tested in observations at terrestrial and space based interferometers, pulsar timing arrays, and the cosmic microwave anisotropy observations.