On fast CP violating interactions in leptogenesis

We show that when the relevant CP violating interactions in leptogenesis are fast, the different matter density asymmetries are determined at each instant by a balance condition between the amount of asymmetry being created and destroyed. This fact allows to understand in a simple way many features of leptogenesis in the strong washout regime. In particular, we find some non-trivial effects of flavour changing interactions that conserve lepton number, which are specially relevant in models for leptogenesis that rely heavily on flavour effects.Comment: V2: To match published version in JCAP. Minor changes, including one figure, with respect to V1. 17 pages, 4 figure

Photon Signatures for Low Energy Supersymmetry Breaking and Broken R-parity

The possible phenomenological consequences of R-parity violating interactions in the framework of low energy supersymmetry breaking are studied. It is pointed out that even very weak R-parity violation would completely overshadow one of the basic signatures of low energy supersymmetry breaking models, that is, the decay of the next to lightest supersymmetric particle into a photon (lepton) and missing energy. Thus, the observation of these decays would put very strong limits on R-parity violating couplings. Vice-versa, if R-parity violation is established experimentally, before a detailed knowledge of the spectrum is obtained, it will be very difficult to distinguish gravity mediated from low energy gauge mediated supersymmetry breaking. Those conclusions are very model independent. We also comment on the possibility of mixing between charged and neutral leptons with charginos and neutralinos, respectively, and its phenomenological consequences for the photon (lepton) signatures, in scenarios where this mixing is generated by the presence of bilinear or trilinear R-parity violating terms in the superpotential.Comment: 12 pages, Late

Study of flavour dependencies in leptogenesis

We study the impact of flavours on the efficiency factors and give analytical and numerical results of the baryon asymmetry taking into account the different charged lepton Yukawa contributions and the complete (diagonal and off-diagonal) $L$ to $B-L$ conversion $A$ matrix. With this treatment we update the lower bound on the lightest right-handed neutrino mass.Comment: 13 pages, 11 figures. typos corrected, some formulae modified. 2 figures and discussion adde

Revisiting the sacred landscapes of Northeast Italy between the 8th century BC and the 2nd century BC.

My thesis offers a humanistic and experiential re-interpretation of the relationship between people, landscape and the gods in Iron Age and Romanisation Northeast Italy (from the 8th century BC to the 2nd centuries BC included). In it I search for, and explore a Venetic sense of place' by appraising the significance of cult practices within a complex network of social groups known as the 'Veneti'. After identifying the shortcomings of current research on Iron Age Veneto - and pre-Roman Italy as a whole -, which is largely typological and site-based with little attention to the landscape context and materiality of meaningful places, I adopted an approach that questions previous landscape and artefact interpretations and challenges monument-biased assumptions. I argue for a thicker and more comprehensive outlook on ancient places, be it 'natural' landscapes or humanly made structures and features. My chief aim is that of investigating and bringing to the fore the complex dynamics of landscape dwelling, navigation, place selection and worship: to do so I endeavoured to produce a rigorous and systematic study of how people used landscape and how they related to the meaningful objects they deposited at selected locales. My original approach includes landscape reconnaissance, a site log, interpretative fieldwork, archival research, ground photography, 'experiential maps', the application of phenomenology to place assessment and material culture/ artefact appraisal, and the use of GIS. I have created a methodology that allows fieldwork to be repeated as it is rigorously documented, and offers an approach to place and material culture that could be used to assess other types of landscapes, and could be applied to prehistoric, protohistoric and historic case studies. Whenever possible I have also sought to integrate ethnological data into my assessment of place, seeking to complement and integrate my knowledge of past cult and ritual in various parts of the Veneto with insights potentially afforded by legends and myths. I used this mixed approach as I believe that landscape perception, use, material culture and local place names and folklore can shed light on how people experienced landscapes and interacted with them. I found that Venetic peoples seemed to be very aware of their land and surroundings when seeking out suitable or significant places for special activities such as burials and cult practices, and certain particularly striking landforms had a very enduring and marked significance, and a deep impact on people through time

CP violation in scatterings, three body processes and the Boltzmann equations for leptogenesis

We obtain the Boltzmann equations for leptogenesis including decay and scattering processes with two and three body initial or final states. We present an explicit computation of the CP violating scattering asymmetries. We analyze their possible impact in leptogenesis, and we discuss the validity of their approximate expressions in terms of the decay asymmetry. In scenarios in which the initial heavy neutrino density vanishes, the inclusion of CP asymmetries in scatterings can enforce a cancellation between the lepton asymmetry generated at early times and the asymmetry produced at later times. We argue that a sizeable amount of washout is crucial for spoiling this cancellation, and we show that in the regimes in which the washouts are particularly weak, the inclusion of CP violation in scatterings yields a reduction in the final value of the lepton asymmetry. In the strong washout regimes the inclusion of CP violation in scatterings still leads to a significant enhancement of the lepton asymmetry at high temperatures; however, due to the independence from the early conditions that is characteristic of these regimes, the final value of the lepton asymmetry remains approximately unchanged.Comment: 24 pages, 6 figures. One appendix added. Some numerical results and corresponding figures (mainly fig. 3) corrected. Final version to be published in JHE