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Author  |
Donini, A.; Hernandez, P.; Lopez-Pavon, J.; Maltoni, M. |
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Title |
Minimal models with light sterile neutrinos |
Type |
Journal Article |
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Year |
2011 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
07 |
Issue |
7 |
Pages |
105 |
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Abstract |
We study the constraints imposed by neutrino oscillation experiments on the minimal extensions of the Standard Model (SM) with n(R) gauge singlet fermions (“right-handed neutrinos”), that can account for neutrino masses. We consider the most general coupling of the new fields to the SM fields, in particular those that break lepton number and we do not assume any a priori hierarchy in the mass parameters. We proceed to analyze these models starting from the lowest level of complexity, defined by the number of extra fermionic degrees of freedom. The simplest choice that has enough free parameters in principle (i.e. two mass differences and two angles) to explain the confirmed solar and atmospheric oscillations corresponds to n(R) = 1. This minimal choice is shown to be excluded by data. The next-to-minimal choice corresponds to n(R) = 2. We perform a systematic study of the full parameter space in the limit of degenerate Majorana masses by requiring that at least two neutrino mass differences correspond to those established by solar and atmospheric oscillations. We identify several types of spectra that can fit long-baseline reactor and accelerator neutrino oscillation data, but fail in explaining solar and/or atmospheric data. The only two solutions that survive are the expected seesaw and quasi-Dirac regions, for which we set lower and upper bounds respectively on the Majorana mass scale. Solar data from neutral current measurements provide essential information to constrain the quasi-Dirac region. The possibility to accommodate the LSND/MiniBoone and reactor anomalies, and the implications for neutrinoless double-beta decay and tritium beta decay are briefly discussed. |
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1126-6708 |
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WOS:000293741500041 |
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no |
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yes |
International Collaboration |
yes |
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Call Number |
IFIC @ elepoucu @ |
Serial |
760 |
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Author |
Donini, A.; Hernandez, P.; Lopez-Pavon, J.; Maltoni, M.; Schwetz, T. |
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Title |
The minimal 3+2 neutrino model versus oscillation anomalies |
Type |
Journal Article |
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Year |
2012 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
07 |
Issue |
7 |
Pages |
161 - 20pp |
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Keywords |
Neutrino Physics; Beyond Standard Model |
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Abstract |
We study the constraints imposed by neutrino oscillation experiments on the minimal extension of the Standard Model that can explain neutrino masses, which requires the addition of just two singlet Weyl fermions. The most general renormalizable couplings of this model imply generically four massive neutrino mass eigenstates while one remains massless: it is therefore a minimal 3+2 model. The possibility to account for the confirmed solar, atmospheric and long-baseline oscillations, together with the LSND/MiniBooNE and reactor anomalies is addressed. We find that the minimal model can fit oscillation data including the anomalies better than the standard 3 nu model and similarly to the 3 + 2 phenomenological models, even though the number of free parameters is much smaller than in the latter. Accounting for the anomalies in the minimal model favours a normal hierarchy of the light states and requires a large reactor angle, in agreement with recent measurements. Our analysis of the model employs a new parametrization of seesaw models that extends the Casas-Ibarra one to regimes where higher order corrections in the light-heavy mixings are significant. |
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[Donini, A.; Hernandez, P.] Univ Valencia, Inst Fis Corpuscular, CSIC, E-46071 Valencia, Spain, Email: andrea.donini@uam.es; |
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Springer |
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English |
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1126-6708 |
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WOS:000307299800039 |
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no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1161 |
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Author |
Drewes, M.; Garbrecht, B.; Hernandez, P.; Kekic, M.; Lopez-Pavon, J.; Racker, J.; Rius, N.; Salvado, J.; Teresi, D. |
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Title |
ARS leptogenesis |
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Journal Article |
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Year |
2018 |
Publication |
International Journal of Modern Physics A |
Abbreviated Journal |
Int. J. Mod. Phys. A |
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33 |
Issue |
5-6 |
Pages |
1842002 - 46pp |
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We review the current status of the leptogenesis scenario originally proposed by Akhmedov, Rubakov and Smirnov (ARS). It takes place in the parametric regime where the right-handed neutrinos are at the electroweak scale or below and the CP-violating effects are induced by the coherent superposition of different right-handed mass eigenstates. Two main theoretical approaches to derive quantum kinetic equations, the Hamiltonian time evolution as well as the Closed-Time-Path technique are presented, and we discuss their relations. For scenarios with two right-handed neutrinos, we chart the viable parameter space. Both, a Bayesian analysis, that determines the most likely configurations for viable leptogenesis given different variants of flat priors, and a determination of the maximally allowed mixing between the light, mostly left-handed, and heavy, mostly right-handed, neutrino states are discussed. Rephasing invariants are shown to be a useful tool to classify and to understand various distinct contributions to ARS leptogenesis that can dominate in different parametric regimes. While these analyses are carried out for the parametric regime where initial asymmetries are generated predominantly from lepton-number conserving, but flavor violating effects, we also review the contributions from lepton-number violating operators and identify the regions of parameter space where these are relevant. |
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[Drewes, M.; Garbrecht, B.] Tech Univ Munich, Phys Dept, James Franck Str, D-85748 Garching, Germany, Email: m.pilar.hernandez@uv.es |
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World Scientific Publ Co Pte Ltd |
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English |
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ISSN |
0217-751x |
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Notes |
WOS:000426586100003 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3508 |
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Author |
Drewes, M.; Klaric, J.; Lopez-Pavon, J. |
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Title |
New benchmark models for heavy neutral lepton searches |
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Journal Article |
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Year |
2022 |
Publication |
European Physical Journal C |
Abbreviated Journal |
Eur. Phys. J. C |
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82 |
Issue |
12 |
Pages |
1176 - 11pp |
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Abstract |
The sensitivity of direct searches for heavy neutral leptons (HNLs) in accelerator-based experiments depends strongly on the particles properties. Commonly used benchmark scenarios are important to ensure comparability and consistency between experimental searches, re-interpretations, and sensitivity studies for different facilities. In models where the HNLs are primarily produced and decay through the weak interaction, benchmarks are in particular defined by fixing the relative strengths of their mixing with SM neutrinos of different flavours, and the interpretation of experimental data is known to strongly depend on those ratios. The commonly used benchmarks in which a single HNL flavour exclusively interacts with one Standard Model generation do not reflect what is found in realistic neutrino mass models. We identify two additional benchmarks for accelerator-based direct HNL searches, which we primarily select based on the requirement to provide a better approximation for the phenomenology of realistic neutrino mass models in view of present and future neutrino oscillation data. |
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[Drewes, M.; Klaric, J.] Catholic Univ Louvain, Ctr Cosmol Particle Phys & Phenomenol, B-1348 Louvain La Neuve, Belgium, Email: marco.drewes@uclouvain.be; |
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Publisher |
Springer |
Place of Publication |
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Editor |
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English |
Summary Language |
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Original Title |
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Abbreviated Series Title |
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Edition |
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ISSN |
1434-6044 |
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Notes |
WOS:000906204200001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5446 |
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Author |
Escudero, M.; Lopez-Pavon, J.; Rius, N.; Sandner, S. |
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Title |
Relaxing cosmological neutrino mass bounds with unstable neutrinos |
Type |
Journal Article |
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Year |
2020 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
12 |
Issue |
12 |
Pages |
119 - 44pp |
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Keywords |
Beyond Standard Model; Cosmology of Theories beyond the SM; Neutrino Physics |
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Abstract |
At present, cosmological observations set the most stringent bound on the neutrino mass scale. Within the standard cosmological model (Lambda CDM), the Planck collaboration reports Sigma m(v)< 0.12 eV at 95 % CL. This bound, taken at face value, excludes many neutrino mass models. However, unstable neutrinos, with lifetimes shorter than the age of the universe <tau>(nu) less than or similar to t(U), represent a particle physics avenue to relax this constraint. Motivated by this fact, we present a taxonomy of neutrino decay modes, categorizing them in terms of particle content and final decay products. Taking into account the relevant phenomenological bounds, our analysis shows that 2-body decaying neutrinos into BSM particles are a promising option to relax cosmological neutrino mass bounds. We then build a simple extension of the type I seesaw scenario by adding one sterile state nu (4) and a Goldstone boson phi, in which nu (i)-> nu (4)phi decays can loosen the neutrino mass bounds up to Sigma m(v) similar to 1 eV, without spoiling the light neutrino mass generation mechanism. Remarkably, this is possible for a large range of the right-handed neutrino masses, from the electroweak up to the GUT scale. We successfully implement this idea in the context of minimal neutrino mass models based on a U(1)(mu-tau) flavor symmetry, which are otherwise in tension with the current bound on Sigma m(v). |
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[Escudero, Miguel] Kings Coll London, Dept Phys, Theoret Particle Phys & Cosmol Grp, London WC2R 2LS, England, Email: miguel.escudero@kcl.ac.uk; |
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Corporate Author |
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Thesis |
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Publisher |
Springer |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1029-8479 |
ISBN |
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Area |
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Conference |
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Notes |
WOS:000601400500005 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4661 |
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