1,804 research outputs found
Model Building and Phenomenology in Grand Unified Theories
No full textThe Standard Model (SM) of particle physics is known to suffer from several flaws, and the upcoming generation of experiments may shed some light onto their solution. Whether there is evidence of new physics or not, theories Beyond the SM (BSM) must be able to accommodate and explain the coming data. The lack of signs of BSM physics so far, calls for a exhaustive exploration beyond the minimal models, in particular Grand Unified theories, for they are able to solve some of the issues of the SM and can make testable predictions. Therefore, we attempt to develop a framework to build Grand Unified models, capable of generating and analysing general non-minimal models. In order to do so, first we create a computational tool to handle the group theoretical component, calculating properties of Lie Groups and their representations. Among them, those of interest to the model building process are the calculation of breaking chains from a group to a subgroup, the decomposition of representations of a group into those of a subgroup and the construction of group invariants. Using some of the capabilities of the group tool, and starting with a set of representations and a breaking chain, we generate all the conceivable models, classifying them to satisfy conditions such as anomaly cancellation and symmetry breaking. We then move on to study the unification of gauge couplings on the models and its consequences on the scale of unification and the scale of supersymmetry breaking, to later constrain them to match phenomenological observables, such as proton decay or current collider searches. We conclude by focusing the analysis on two specific models, a minimal supersymmetric SO(10) model, with some interesting predictions for future colliders, and a flipped SU(5)xU(1) model, which serves as the triggering mechanism for the end of the inflationary epoch in the early universe
Exotic neutrinoless double beta decay with Majoron-like emission
No full textWe discuss a novel mode of neutrinoless double-β decay with emission of a light Majoron-like scalar particle φ which couples via an effective 7-dimensional operator with a (V + A) lepton current and (V ± A) quark currents leading to a long-range contribution. Future double-β decay searches are sensitive to scales of the order ΛNP ≈ 1 TeV for the effective operator. In a left-right symmetric model, this mode can probe right-handed W boson masses up to 25 TeV
Neutrinos and collider physics
No full textModels of neutrino mass generation constitute well motivated scenarios of Beyond-the-Standard-Model physics. The interplay between high energy collider physics and low energy searches provides us with an effective approach to rule out, constrain and pinpoint such models. In this report, we give a brief overview of examples where collider searches at the LHC can help determine the mechanism of light neutrino mass generation and potentially falsify baryogenesis mechanisms
Neutrinos and BSM physics
No full textModels of neutrino mass generation constitute well motivated scenarios of Beyond-the-StandardModel
physics. The interplay between high energy collider physics and low energy searches provides
us with an effective approach to rule out, constrain and pinpoint such models. In this report,
we give a brief overview of examples where collider searches at the LHC can help determine the
mechanism of light neutrino mass generation and potentially falsify baryogenesis mechanisms
A modern introduction to neutrino physics
No full textThis book reviews the field in a concise fashion and highlights the most pressing issues and areas of strongest topical interest. It provides a clear, self-contained, and logical treatment of the fundamental physics aspects, appropriate for graduate students. Starting with the relevant basics of the SM, neutrinos are introduced, and the quantum mechanical effect of oscillations is explained in detail. A strong focus is then set on the phenomenon of lepton number violation, especially in 0nbb decay, as the crucial probe to understand the nature of neutrinos. The role of neutrinos in astrophysics, expected to be of increasing importance for future research, is then described. Finally, models to explain the neutrino properties are outlined. The central theme of the book is the nature of neutrino masses and the above topics will revolve around this issue
The Aresys FF-SAR Service for Cryosat-2 at ESA GPOD
No full textThe Fully-Focused SAR (FF-SAR) processing, introduced in Egido and Smith (2016) allows obtaining a maximum resolution of 0.5 m in the along-track direction. It provides significant benefits for inland water altimetry investigations allowing the successful investigation of very small rivers and canals (Kleinherenbrink, 2020) that are typically harder to be analysed by using unfocused Delay-Doppler SAR (DD-SAR) data (about 300 m resolution in the along-track direction).In its development, two major limitations were associated with the FF-SAR processing: 1) the presence of evenly spaced high sidelobes in the Point Target Response (PTR) due to the closed-loop burst mode implemented in Sentinel-3 & Cryosat-2 altimeter payloads, used for initial FF-SAR investigations, and 2) the heavy computational burden with respect to the unfocused DD-SAR processing. The first limitation can be overcome by designing the radar system differently adopting an open-loop transmission scheme as, for instance, the one implemented in the altimeter payload of the Sentinel-6 Michael Freilich mission, launched on 21 November 2020. The second limitation has been addressed in research works following Egido and Smith (2016) indicating that an improvement in terms of computational burden can be achieved by adopting algorithms in the frequency domain (Guccione et al., 2018).Being the role of FF-SAR for future inland water altimetry well understood, along with the possibility to see it implemented with reduced drawbacks during the Sentinel-6 Michael Freilich mission, a collaboration has started between the ESA GPOD Team, already hosting the successful SARvatore services portfolio for unfocused SAR & SARin altimetry, and Aresys. Aresys has developed a generic FF-SAR prototype processor, that is able to process data acquisition from different instruments and exploiting the frequency-domain Omega-K algorithm (Guccione et al., 2018 & Scagliola et al., 2018). The Aresys's FFSAR prototype processor for CryoSat-2 allows users to process, on line and on demand, low-level CryoSat FBR products in SAR mode up to FF-SAR Level-1 products with self-customized options. Additionally a wide set of processing parameters is configurable, allowing as an example to select the along-track resolution or to obtain FFSAR multilooked waveforms at the desired posting rate. The collaboration led to the creation of a new service for the processing of CryoSat Baseline D data in FF-SAR mode. Users will be able to select the following options: 1) range oversampling factor, 2) bandwidth factor (responsible for the along-track resolution value) and 3) multilook posting rate (1Hz-500Hz). Geophysical corrections and L2 estimates from both a threshold peak retracker and an ALES-like subwaveform retracker are part of the output package. In preliminary open ocean analyses, very good results on SSH noise have been obtained by the ALES-like subwaveform retracker.In this presentation, the Aresys FF-SAR prototype processor is described and the outcome of some preliminary validation activities, performed by a group of altimetry researchers, is reported. The service is scheduled to open to all GPOD/SARvatore users in the first semester of 2021. Future evolutions should include the extension of the service to Sentinel-3 and Sentinel-6 data.Astrodynamics & Space Mission
Statistical analysis of beta decays and the effective value of g(A) in the proton-neutron quasiparticle random-phase approximation framework
No full textWe perform a Markov chain Monte Carlo (MCMC) statistical analysis of a number of measured ground-state-to-ground-state single β+/electron-capture and β− decays in the nuclear mass range of A=62–142. The corresponding experimental comparative half-lives (logft values) are compared with the theoretical ones obtained by the use of the proton-neutron quasiparticle random-phase approximation (pnQRPA) with G-matrix-based effective interactions. The MCMC analysis is performed separately for 47 isobaric triplets and 28 more extended isobaric chains of nuclei to extract values and uncertainties for the effective axial-vector coupling constant gA in nuclear-structure calculations performed in the pnQRPA framework. As far as available, measured half-lives for two-neutrino ββ− decays occurring in the studied isobaric chains are analyzed as well
The Devil's altar? : crime and the early modern public house
No full textWas the early modern public house really such a dangerous place, as Puritan preachers (and many historians) suggested? This article discusses offences by publicans and patrons. It argues that the evidence for crime needs to be carefully contextualised and that taverns could stabilise as well as threaten the social order
- …
